SEC Info  
    Home      Search      My Interests      Help      Sign In      Please Sign In

Medifast Inc. – ‘10-Q’ for 9/30/22 – ‘EX-101.DEF’

On:  Thursday, 11/3/22, at 4:51pm ET   ·   For:  9/30/22   ·   Accession #:  1628280-22-28255   ·   File #:  1-31573

Previous ‘10-Q’:  ‘10-Q’ on 8/3/22 for 6/30/22   ·   Next:  ‘10-Q’ on 5/1/23 for 3/31/23   ·   Latest:  ‘10-Q’ on 4/29/24 for 3/31/24   ·   2 References:   

Find Words in Filings emoji
 
  in    Show  and   Hints

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

11/03/22  Medifast Inc.                     10-Q        9/30/22   52:4.7M                                   Workiva Inc Wde… FA01/FA

Quarterly Report   —   Form 10-Q

Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 10-Q        Quarterly Report                                    HTML   1.20M 
 2: EX-31.1     Certification -- §302 - SOA'02                      HTML     20K 
 3: EX-31.2     Certification -- §302 - SOA'02                      HTML     20K 
 4: EX-32.1     Certification -- §906 - SOA'02                      HTML     18K 
10: R1          Cover                                               HTML     68K 
11: R2          Condensed Consolidated Statements of Income         HTML     98K 
                (Unaudited)                                                      
12: R3          Condensed Consolidated Statements of Comprehensive  HTML     43K 
                Income (Unaudited)                                               
13: R4          Condensed Consolidated Balance Sheets (Unaudited)   HTML    107K 
14: R5          Condensed Consolidated Balance Sheets               HTML     24K 
                (Parenthetical)                                                  
15: R6          Condensed Consolidated Statements of Cash Flows     HTML     92K 
                (Unaudited)                                                      
16: R7          Condensed Consolidated Statements of Changes in     HTML    113K 
                Stockholders' Equity (Unaudited)                                 
17: R8          Summary of Significant Accounting Policies          HTML     23K 
18: R9          Inventories                                         HTML     26K 
19: R10         Earnings Per Share                                  HTML     39K 
20: R11         Share-Based Compensation                            HTML     82K 
21: R12         Leases                                              HTML     32K 
22: R13         Accumulated Other Comprehensive Income              HTML     24K 
23: R14         Financial Instruments                               HTML     65K 
24: R15         Debt                                                HTML     26K 
25: R16         Accelerated Share Repurchase ("Asr") Program        HTML     18K 
26: R17         Summary of Significant Accounting Policies          HTML     33K 
                (Policies)                                                       
27: R18         Inventories (Tables)                                HTML     26K 
28: R19         Earnings Per Share (Tables)                         HTML     37K 
29: R20         Share-Based Compensation (Tables)                   HTML     79K 
30: R21         Leases (Tables)                                     HTML     32K 
31: R22         Accumulated Other Comprehensive Income (Tables)     HTML     24K 
32: R23         Financial Instruments (Tables)                      HTML     62K 
33: R24         Inventories (Details)                               HTML     31K 
34: R25         EARNINGS PER SHARE - Computation of Basic and       HTML     55K 
                Diluted EPS (Details)                                            
35: R26         EARNINGS PER SHARE - Narrative (Details)            HTML     18K 
36: R27         SHARE-BASED COMPENSATION - Narrative (Details)      HTML     77K 
37: R28         SHARE-BASED COMPENSATION - Stock Options Activity   HTML     34K 
                (Details)                                                        
38: R29         SHARE-BASED COMPENSATION - Restricted Stock         HTML     40K 
                Activity (Details)                                               
39: R30         SHARE-BASED COMPENSATION - Summary of               HTML     38K 
                Performance-based Share Awards (Details)                         
40: R31         LEASES - Narrative (Details)                        HTML     29K 
41: R32         LEASES - Supplemental Cash Flow Information         HTML     25K 
                (Details)                                                        
42: R33         LEASES - Future Minimum Lease Commitments           HTML     34K 
                (Details)                                                        
43: R34         ACCUMULATED OTHER COMPREHENSIVE INCOME -            HTML     30K 
                Accumulated Other Comprehensive Income (Details)                 
44: R35         FINANCIAL INSTRUMENTS - Cash and Financial Assets   HTML     47K 
                That are Measured at Fair Value on a Recurring                   
                Basis for Each of the Hierarchy Levels (Details)                 
45: R36         FINANCIAL INSTRUMENTS - Narrative (Details)         HTML     18K 
46: R37         DEBT - Narrative (Details)                          HTML     42K 
47: R38         Accelerated Share Repurchase ("Asr") Program        HTML     20K 
                (Details)                                                        
50: XML         IDEA XML File -- Filing Summary                      XML     87K 
48: XML         XBRL Instance -- med-20220930_htm                    XML   1.15M 
49: EXCEL       IDEA Workbook of Financial Reports                  XLSX     78K 
 6: EX-101.CAL  XBRL Calculations -- med-20220930_cal                XML    119K 
 7: EX-101.DEF  XBRL Definitions -- med-20220930_def                 XML    229K 
 8: EX-101.LAB  XBRL Labels -- med-20220930_lab                      XML    912K 
 9: EX-101.PRE  XBRL Presentations -- med-20220930_pre               XML    510K 
 5: EX-101.SCH  XBRL Schema -- med-20220930                          XSD     81K 
51: JSON        XBRL Instance as JSON Data -- MetaLinks              245±   366K 
52: ZIP         XBRL Zipped Folder -- 0001628280-22-028255-xbrl      Zip    235K 


‘EX-101.DEF’   —   XBRL Definitions — med-20220930_def


This Exhibit is an XBRL XML File.


                                                                                                                                                                                
<?xml version="1.0" encoding="windows-1252"?>
<!-- XBRL Document Created with Wdesk from Workiva -->
<!-- Copyright 2022 Workiva -->
<!-- r:1ae599f9-ff00-4d75-90b9-110349ab0236,g:6d08fa26-e8d0-4031-9c9e-a858e7464a0f -->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
<link:roleRef roleURI="http://www.medifast1.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITYUNAUDITED" xlink:type="simple" xlink:href="med-20220930.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITYUNAUDITED"/>
<link:definitionLink xlink:role="http://www.medifast1.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITYUNAUDITED" xlink:type="extended" id="i3e9ef29b99c94ea984fadd87682dd094_CONDENSEDCONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITYUNAUDITED">
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_ef1bcf94-5607-4a12-9bb2-693e92551716" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementLineItems"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ef1bcf94-5607-4a12-9bb2-693e92551716" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_743342ae-fe92-4644-b55f-bc19e2c00e9e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesIssued"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_CommonStockSharesIssued_743342ae-fe92-4644-b55f-bc19e2c00e9e" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_cd3f3789-01ee-4ba1-980f-cfc2093c7751" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_StockholdersEquity_cd3f3789-01ee-4ba1-980f-cfc2093c7751" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_c4d792f2-9bff-4f27-b0ea-3fbce42e507e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_NetIncomeLoss_c4d792f2-9bff-4f27-b0ea-3fbce42e507e" xlink:type="arc" order="3"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_cc86e065-9ea2-4cf1-8a55-6bb0d22c5137" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_cc86e065-9ea2-4cf1-8a55-6bb0d22c5137" xlink:type="arc" order="4"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationAndExerciseOfStockOptions_c1c6b055-2a0c-403b-a3a4-430810f41df5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationAndExerciseOfStockOptions"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationAndExerciseOfStockOptions_c1c6b055-2a0c-403b-a3a4-430810f41df5" xlink:type="arc" order="5"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_24e7654d-15ae-4b05-8a27-e0f8f62db557" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_24e7654d-15ae-4b05-8a27-e0f8f62db557" xlink:type="arc" order="6"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_ff80789f-788d-4b1c-917d-0a686da9fb78" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_ff80789f-788d-4b1c-917d-0a686da9fb78" xlink:type="arc" order="7"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_4e53a392-e5a4-4e38-b8ba-63d3e4263dac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_4e53a392-e5a4-4e38-b8ba-63d3e4263dac" xlink:type="arc" order="8"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_5d7feaaa-7145-49f8-a309-86f0f014ae93" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_5d7feaaa-7145-49f8-a309-86f0f014ae93" xlink:type="arc" order="9"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_3debd9d6-6b7e-44b9-8ffc-092c270e52d1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_3debd9d6-6b7e-44b9-8ffc-092c270e52d1" xlink:type="arc" order="10"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesRetired_e5c3aeb2-a0cd-46bf-9c1b-f4fb40f05300" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockSharesRetired"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_TreasuryStockSharesRetired_e5c3aeb2-a0cd-46bf-9c1b-f4fb40f05300" xlink:type="arc" order="11"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockRetiredCostMethodAmount_757350d8-8987-4d0f-aa05-8c3d0c67826c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockRetiredCostMethodAmount"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_TreasuryStockRetiredCostMethodAmount_757350d8-8987-4d0f-aa05-8c3d0c67826c" xlink:type="arc" order="12"/>
<link:loc xlink:type="locator" xlink:label="loc_med_AdjustmentsToPaidInCapitalShareRepurchasesNotYetSettled_5ae06770-d9d8-4aa4-be2b-73c1ed1353eb" xlink:href="med-20220930.xsd#med_AdjustmentsToPaidInCapitalShareRepurchasesNotYetSettled"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_med_AdjustmentsToPaidInCapitalShareRepurchasesNotYetSettled_5ae06770-d9d8-4aa4-be2b-73c1ed1353eb" xlink:type="arc" order="13"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcceleratedShareRepurchaseProgramAdjustment_227898df-1199-484a-8e9f-6e3be1c19349" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AcceleratedShareRepurchaseProgramAdjustment"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_AcceleratedShareRepurchaseProgramAdjustment_227898df-1199-484a-8e9f-6e3be1c19349" xlink:type="arc" order="14"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_f185b45f-b6d0-4b55-82cb-4d089ae0af3e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_f185b45f-b6d0-4b55-82cb-4d089ae0af3e" xlink:type="arc" order="15"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_04f9ef3d-83d1-4efb-ae8e-c83713ea0cb4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DividendsCommonStockCash"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b1c3ec23-26ff-4327-9b88-a8a431832129" xlink:to="loc_us-gaap_DividendsCommonStockCash_04f9ef3d-83d1-4efb-ae8e-c83713ea0cb4" xlink:type="arc" order="16"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_4c4fd010-4be7-4a24-bda2-deb99b7c269a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesIssued"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_00019b0b-4e91-49b9-940a-90ed1b46675c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_cc2e2bc7-1fc9-4f06-9e8c-842829561748" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_ef1bcf94-5607-4a12-9bb2-693e92551716" xlink:to="loc_us-gaap_StatementTable_cc2e2bc7-1fc9-4f06-9e8c-842829561748" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_2ee8d58b-c072-494e-82ac-94d7a48728c3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_cc2e2bc7-1fc9-4f06-9e8c-842829561748" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_2ee8d58b-c072-494e-82ac-94d7a48728c3" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_2ee8d58b-c072-494e-82ac-94d7a48728c3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2ee8d58b-c072-494e-82ac-94d7a48728c3" xlink:to="loc_us-gaap_EquityComponentDomain_2ee8d58b-c072-494e-82ac-94d7a48728c3_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_bbe90df0-21fa-4cd9-a6e1-83724a94d4a5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2ee8d58b-c072-494e-82ac-94d7a48728c3" xlink:to="loc_us-gaap_EquityComponentDomain_bbe90df0-21fa-4cd9-a6e1-83724a94d4a5" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_2931acc5-9521-4eb1-883d-b06be80865fa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_bbe90df0-21fa-4cd9-a6e1-83724a94d4a5" xlink:to="loc_us-gaap_CommonStockMember_2931acc5-9521-4eb1-883d-b06be80865fa" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_521f9a16-2223-47e3-ae94-03271ab8868a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_bbe90df0-21fa-4cd9-a6e1-83724a94d4a5" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_521f9a16-2223-47e3-ae94-03271ab8868a" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_b8863288-2d35-4010-a52a-1c2a58c7b4fe" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_bbe90df0-21fa-4cd9-a6e1-83724a94d4a5" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_b8863288-2d35-4010-a52a-1c2a58c7b4fe" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_9a523ca0-460c-4145-806d-bc5453bd9719" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetainedEarningsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_bbe90df0-21fa-4cd9-a6e1-83724a94d4a5" xlink:to="loc_us-gaap_RetainedEarningsMember_9a523ca0-460c-4145-806d-bc5453bd9719" xlink:type="arc" order="3"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_472e82f1-728e-46b3-8fde-b6a9f405948b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockCommonMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_bbe90df0-21fa-4cd9-a6e1-83724a94d4a5" xlink:to="loc_us-gaap_TreasuryStockCommonMember_472e82f1-728e-46b3-8fde-b6a9f405948b" xlink:type="arc" order="4"/>
</link:definitionLink>
<link:roleRef roleURI="http://www.medifast1.com/role/EARNINGSPERSHARENarrativeDetails" xlink:type="simple" xlink:href="med-20220930.xsd#EARNINGSPERSHARENarrativeDetails"/>
<link:definitionLink xlink:role="http://www.medifast1.com/role/EARNINGSPERSHARENarrativeDetails" xlink:type="extended" id="i9382a1a8aca74d7da1cb7f7b17257fc6_EARNINGSPERSHARENarrativeDetails">
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_1fb4cd38-ff04-4b18-8ca0-8f089d21b3a0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementLineItems"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_68fcae99-001f-43ce-bc8b-bcd6fc46633e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1fb4cd38-ff04-4b18-8ca0-8f089d21b3a0" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_68fcae99-001f-43ce-bc8b-bcd6fc46633e" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_734c6744-9473-4c3e-8b29-a1346011f2da" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_1fb4cd38-ff04-4b18-8ca0-8f089d21b3a0" xlink:to="loc_us-gaap_StatementTable_734c6744-9473-4c3e-8b29-a1346011f2da" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_29f5df8a-2b78-4b5d-b0fa-aa37a2cf4661" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_734c6744-9473-4c3e-8b29-a1346011f2da" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_29f5df8a-2b78-4b5d-b0fa-aa37a2cf4661" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_29f5df8a-2b78-4b5d-b0fa-aa37a2cf4661_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_29f5df8a-2b78-4b5d-b0fa-aa37a2cf4661" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_29f5df8a-2b78-4b5d-b0fa-aa37a2cf4661_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_6adcb098-dc2f-4a53-8f0f-0861bfcf659d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_29f5df8a-2b78-4b5d-b0fa-aa37a2cf4661" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_6adcb098-dc2f-4a53-8f0f-0861bfcf659d" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_187fe810-a525-4f52-8c20-26bf0fe37afb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedStockMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_6adcb098-dc2f-4a53-8f0f-0861bfcf659d" xlink:to="loc_us-gaap_RestrictedStockMember_187fe810-a525-4f52-8c20-26bf0fe37afb" xlink:type="arc" order="0"/>
</link:definitionLink>
<link:roleRef roleURI="http://www.medifast1.com/role/SHAREBASEDCOMPENSATIONNarrativeDetails" xlink:type="simple" xlink:href="med-20220930.xsd#SHAREBASEDCOMPENSATIONNarrativeDetails"/>
<link:definitionLink xlink:role="http://www.medifast1.com/role/SHAREBASEDCOMPENSATIONNarrativeDetails" xlink:type="extended" id="i064d28e2e07c4e3caf3194bb3c2920e7_SHAREBASEDCOMPENSATIONNarrativeDetails">
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_18d7df5f-a532-4d62-8d6f-651f86a7c45e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_18d7df5f-a532-4d62-8d6f-651f86a7c45e" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_f3791204-ee87-47a1-b54a-a5bd73addaf5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_f3791204-ee87-47a1-b54a-a5bd73addaf5" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_431433f6-5126-4070-b8f0-d9b4d5a56421" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_431433f6-5126-4070-b8f0-d9b4d5a56421" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_314b0954-bb88-40e5-b43b-6c12fb2ba7a7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_314b0954-bb88-40e5-b43b-6c12fb2ba7a7" xlink:type="arc" order="3"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_15bd26c3-402e-4624-809c-f8a272573833" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_15bd26c3-402e-4624-809c-f8a272573833" xlink:type="arc" order="4"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_3cafed22-4b7d-421f-be73-cf7fb74b6e08" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_3cafed22-4b7d-421f-be73-cf7fb74b6e08" xlink:type="arc" order="5"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_2b618cb7-aa5b-433d-8ede-7ab504226a0c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_2b618cb7-aa5b-433d-8ede-7ab504226a0c" xlink:type="arc" order="6"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_4173137c-a311-48df-828b-d93eb8f8f9a2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_4173137c-a311-48df-828b-d93eb8f8f9a2" xlink:type="arc" order="7"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_07be1230-0619-4d69-85d0-7f5eb1ac1c24" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_07be1230-0619-4d69-85d0-7f5eb1ac1c24" xlink:type="arc" order="8"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_c4cf26fc-88fd-4a26-96d2-18515c9c7f64" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_c4cf26fc-88fd-4a26-96d2-18515c9c7f64" xlink:type="arc" order="9"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_b2624baa-9470-4de7-9bdb-fe48253877ac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_b2624baa-9470-4de7-9bdb-fe48253877ac" xlink:type="arc" order="10"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_0d1ac0bc-b425-4ace-a08f-98aedb55ce0c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_0d1ac0bc-b425-4ace-a08f-98aedb55ce0c" xlink:type="arc" order="11"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_f84f7485-acc7-47b6-a0dc-b9f88d2bcdde" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_f84f7485-acc7-47b6-a0dc-b9f88d2bcdde" xlink:type="arc" order="12"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_753eca97-a699-424a-850c-7133dab2d96c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_753eca97-a699-424a-850c-7133dab2d96c" xlink:type="arc" order="13"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_e12e85dd-4b3f-4365-9440-d07d53487301" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_e12e85dd-4b3f-4365-9440-d07d53487301" xlink:type="arc" order="14"/>
<link:loc xlink:type="locator" xlink:label="loc_med_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesEarnedPercentage_eb1cc02d-4f37-4024-971c-43d6efa60f56" xlink:href="med-20220930.xsd#med_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesEarnedPercentage"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_med_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesEarnedPercentage_eb1cc02d-4f37-4024-971c-43d6efa60f56" xlink:type="arc" order="15"/>
<link:loc xlink:type="locator" xlink:label="loc_med_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesEarnedPerformancePeriod_7aad7c4e-e9f0-4534-afc9-be5c8bcc17d7" xlink:href="med-20220930.xsd#med_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesEarnedPerformancePeriod"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_med_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesEarnedPerformancePeriod_7aad7c4e-e9f0-4534-afc9-be5c8bcc17d7" xlink:type="arc" order="16"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_f74eb03c-9245-4d3d-99d5-97b75b8ec2f6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_f74eb03c-9245-4d3d-99d5-97b75b8ec2f6" xlink:type="arc" order="17"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_9e70f8ff-fc53-495b-b9e9-4fd46b1a362e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_9e70f8ff-fc53-495b-b9e9-4fd46b1a362e" xlink:type="arc" order="18"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_861e086f-2278-4ca0-b1e7-c2911bb97508" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_861e086f-2278-4ca0-b1e7-c2911bb97508" xlink:type="arc" order="19"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e512f51d-bd57-431f-bede-d8516d4b0088" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a859e31a-768c-40ff-9295-46c70eb828d0" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e512f51d-bd57-431f-bede-d8516d4b0088" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_9227d7a0-4cd1-4a02-80d9-179e9e45d5fd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e512f51d-bd57-431f-bede-d8516d4b0088" xlink:to="loc_us-gaap_AwardTypeAxis_9227d7a0-4cd1-4a02-80d9-179e9e45d5fd" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_9227d7a0-4cd1-4a02-80d9-179e9e45d5fd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_9227d7a0-4cd1-4a02-80d9-179e9e45d5fd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_9227d7a0-4cd1-4a02-80d9-179e9e45d5fd_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_78c18b21-87b5-42e2-817f-eab49b4a1716" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_9227d7a0-4cd1-4a02-80d9-179e9e45d5fd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_78c18b21-87b5-42e2-817f-eab49b4a1716" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_34a35bd3-d7b4-4bed-a72c-0f10616d7390" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_78c18b21-87b5-42e2-817f-eab49b4a1716" xlink:to="loc_us-gaap_EmployeeStockOptionMember_34a35bd3-d7b4-4bed-a72c-0f10616d7390" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_9940262e-b058-4587-8221-a6c2d8f98d41" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedStockMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_78c18b21-87b5-42e2-817f-eab49b4a1716" xlink:to="loc_us-gaap_RestrictedStockMember_9940262e-b058-4587-8221-a6c2d8f98d41" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_69547e95-6c33-49f3-93f2-d8cad5ba3cd1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PerformanceSharesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_78c18b21-87b5-42e2-817f-eab49b4a1716" xlink:to="loc_us-gaap_PerformanceSharesMember_69547e95-6c33-49f3-93f2-d8cad5ba3cd1" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_434a7827-d1a1-4d05-b0da-3b61a3b2bfca" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e512f51d-bd57-431f-bede-d8516d4b0088" xlink:to="loc_srt_RangeAxis_434a7827-d1a1-4d05-b0da-3b61a3b2bfca" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_434a7827-d1a1-4d05-b0da-3b61a3b2bfca_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_434a7827-d1a1-4d05-b0da-3b61a3b2bfca" xlink:to="loc_srt_RangeMember_434a7827-d1a1-4d05-b0da-3b61a3b2bfca_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_9d93998c-c62d-4421-9908-548393944415" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_434a7827-d1a1-4d05-b0da-3b61a3b2bfca" xlink:to="loc_srt_RangeMember_9d93998c-c62d-4421-9908-548393944415" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_0c1bee4f-5b11-49b2-ae2b-55cc9f8bc00a" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_9d93998c-c62d-4421-9908-548393944415" xlink:to="loc_srt_MinimumMember_0c1bee4f-5b11-49b2-ae2b-55cc9f8bc00a" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_5502ab48-2798-46c9-8f39-9dc15a07476c" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_9d93998c-c62d-4421-9908-548393944415" xlink:to="loc_srt_MaximumMember_5502ab48-2798-46c9-8f39-9dc15a07476c" xlink:type="arc" order="1"/>
</link:definitionLink>
<link:roleRef roleURI="http://www.medifast1.com/role/SHAREBASEDCOMPENSATIONRestrictedStockActivityDetails" xlink:type="simple" xlink:href="med-20220930.xsd#SHAREBASEDCOMPENSATIONRestrictedStockActivityDetails"/>
<link:definitionLink xlink:role="http://www.medifast1.com/role/SHAREBASEDCOMPENSATIONRestrictedStockActivityDetails" xlink:type="extended" id="i050d13120de141b9aaedbb8574ff6cf6_SHAREBASEDCOMPENSATIONRestrictedStockActivityDetails">
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d88f3c57-5f84-4fcc-88b4-656a976d24c7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4bef2596-d15e-4853-a3f7-d4039a043fa6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d88f3c57-5f84-4fcc-88b4-656a976d24c7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4bef2596-d15e-4853-a3f7-d4039a043fa6" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_457f41ff-1e7c-462c-be24-7ff84bbf8f28" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4bef2596-d15e-4853-a3f7-d4039a043fa6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_457f41ff-1e7c-462c-be24-7ff84bbf8f28" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_1a87ab17-1f49-4161-8224-e0d626e6c12c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4bef2596-d15e-4853-a3f7-d4039a043fa6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_1a87ab17-1f49-4161-8224-e0d626e6c12c" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_d5cc0eec-6121-435f-a90c-4b91e2d40565" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4bef2596-d15e-4853-a3f7-d4039a043fa6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_d5cc0eec-6121-435f-a90c-4b91e2d40565" xlink:type="arc" order="3"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_ba58c422-d8a2-4379-ad94-3cc294369321" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4bef2596-d15e-4853-a3f7-d4039a043fa6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_ba58c422-d8a2-4379-ad94-3cc294369321" xlink:type="arc" order="4"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_0b25d288-714d-45fc-ab15-d8e8d25d6541" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_37d523f9-ab3b-49d4-972a-7cf384bc8c33" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d88f3c57-5f84-4fcc-88b4-656a976d24c7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_37d523f9-ab3b-49d4-972a-7cf384bc8c33" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_b6025cae-4ebb-48ad-87ed-aa1d7e1d9bc5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_37d523f9-ab3b-49d4-972a-7cf384bc8c33" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_b6025cae-4ebb-48ad-87ed-aa1d7e1d9bc5" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_8261ddc3-aeb3-4a99-bbbd-8401e507d664" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_37d523f9-ab3b-49d4-972a-7cf384bc8c33" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_8261ddc3-aeb3-4a99-bbbd-8401e507d664" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_cab9f988-466d-4073-9d25-cce944a8c059" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_37d523f9-ab3b-49d4-972a-7cf384bc8c33" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_cab9f988-466d-4073-9d25-cce944a8c059" xlink:type="arc" order="3"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_4a7b627f-bf01-4a65-b117-fffd2c8faced" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_37d523f9-ab3b-49d4-972a-7cf384bc8c33" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_4a7b627f-bf01-4a65-b117-fffd2c8faced" xlink:type="arc" order="4"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_e5817817-7ad6-443d-b4a9-775e9eaa6b4f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_98f083be-d321-4131-82c7-d5b6bcb2df12" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d88f3c57-5f84-4fcc-88b4-656a976d24c7" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_98f083be-d321-4131-82c7-d5b6bcb2df12" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_030e319c-9db4-4fdb-86ce-997ca5014b95" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_98f083be-d321-4131-82c7-d5b6bcb2df12" xlink:to="loc_us-gaap_AwardTypeAxis_030e319c-9db4-4fdb-86ce-997ca5014b95" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_030e319c-9db4-4fdb-86ce-997ca5014b95_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_030e319c-9db4-4fdb-86ce-997ca5014b95" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_030e319c-9db4-4fdb-86ce-997ca5014b95_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6a65bcb1-32b2-4617-9555-64774f37f87d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_030e319c-9db4-4fdb-86ce-997ca5014b95" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6a65bcb1-32b2-4617-9555-64774f37f87d" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_a2fb4b4d-9008-4e25-b189-bac681115a95" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedStockMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6a65bcb1-32b2-4617-9555-64774f37f87d" xlink:to="loc_us-gaap_RestrictedStockMember_a2fb4b4d-9008-4e25-b189-bac681115a95" xlink:type="arc" order="0"/>
</link:definitionLink>
<link:roleRef roleURI="http://www.medifast1.com/role/SHAREBASEDCOMPENSATIONSummaryofPerformancebasedShareAwardsDetails" xlink:type="simple" xlink:href="med-20220930.xsd#SHAREBASEDCOMPENSATIONSummaryofPerformancebasedShareAwardsDetails"/>
<link:definitionLink xlink:role="http://www.medifast1.com/role/SHAREBASEDCOMPENSATIONSummaryofPerformancebasedShareAwardsDetails" xlink:type="extended" id="ide4d0163184744aaacb3effcdc3764e3_SHAREBASEDCOMPENSATIONSummaryofPerformancebasedShareAwardsDetails">
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a2b4f832-fa54-460e-ad50-3e0ea47ab0c7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_38cc16a6-b2a2-40fc-845f-fee918ea8280" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a2b4f832-fa54-460e-ad50-3e0ea47ab0c7" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_38cc16a6-b2a2-40fc-845f-fee918ea8280" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_00aab1fa-42ac-429d-bc4f-8b04de7ddb68" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a2b4f832-fa54-460e-ad50-3e0ea47ab0c7" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_00aab1fa-42ac-429d-bc4f-8b04de7ddb68" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3cb9229a-7092-48d1-81be-4160f7ae691f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a2b4f832-fa54-460e-ad50-3e0ea47ab0c7" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3cb9229a-7092-48d1-81be-4160f7ae691f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_691b1cbe-c961-4649-a5c5-0c5ca3cac073" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3cb9229a-7092-48d1-81be-4160f7ae691f" xlink:to="loc_us-gaap_AwardTypeAxis_691b1cbe-c961-4649-a5c5-0c5ca3cac073" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_691b1cbe-c961-4649-a5c5-0c5ca3cac073_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_691b1cbe-c961-4649-a5c5-0c5ca3cac073" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_691b1cbe-c961-4649-a5c5-0c5ca3cac073_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_61fa37e2-45aa-4486-b47f-75f42d22313f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_691b1cbe-c961-4649-a5c5-0c5ca3cac073" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_61fa37e2-45aa-4486-b47f-75f42d22313f" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_med_OptionsAndRestrictedStockMember_82e8d0aa-3214-47b7-af2d-23d90ee0edfa" xlink:href="med-20220930.xsd#med_OptionsAndRestrictedStockMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_61fa37e2-45aa-4486-b47f-75f42d22313f" xlink:to="loc_med_OptionsAndRestrictedStockMember_82e8d0aa-3214-47b7-af2d-23d90ee0edfa" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_med_MarketAndPerformanceSharesMember_d0445e3b-3287-4add-b987-3d902eabc616" xlink:href="med-20220930.xsd#med_MarketAndPerformanceSharesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_61fa37e2-45aa-4486-b47f-75f42d22313f" xlink:to="loc_med_MarketAndPerformanceSharesMember_d0445e3b-3287-4add-b987-3d902eabc616" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_615f68d1-2927-46dc-bc42-6f4e09d15cca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PerformanceSharesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_61fa37e2-45aa-4486-b47f-75f42d22313f" xlink:to="loc_us-gaap_PerformanceSharesMember_615f68d1-2927-46dc-bc42-6f4e09d15cca" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateAxis_3a8ac5b1-786f-4c05-af33-b0a782720115" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardDateAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3cb9229a-7092-48d1-81be-4160f7ae691f" xlink:to="loc_us-gaap_AwardDateAxis_3a8ac5b1-786f-4c05-af33-b0a782720115" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateDomain_3a8ac5b1-786f-4c05-af33-b0a782720115_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardDateDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardDateAxis_3a8ac5b1-786f-4c05-af33-b0a782720115" xlink:to="loc_us-gaap_AwardDateDomain_3a8ac5b1-786f-4c05-af33-b0a782720115_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateDomain_f0710092-d33b-4aa9-94ad-b25c600f81f4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardDateDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardDateAxis_3a8ac5b1-786f-4c05-af33-b0a782720115" xlink:to="loc_us-gaap_AwardDateDomain_f0710092-d33b-4aa9-94ad-b25c600f81f4" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_med_GrantedIn2022Member_70d995a3-488b-4606-b46c-9f67b7d0c847" xlink:href="med-20220930.xsd#med_GrantedIn2022Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_f0710092-d33b-4aa9-94ad-b25c600f81f4" xlink:to="loc_med_GrantedIn2022Member_70d995a3-488b-4606-b46c-9f67b7d0c847" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_med_GrantedIn2021Member_03ebd95e-0d5a-48d5-b273-95b1f51c6f09" xlink:href="med-20220930.xsd#med_GrantedIn2021Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_f0710092-d33b-4aa9-94ad-b25c600f81f4" xlink:to="loc_med_GrantedIn2021Member_03ebd95e-0d5a-48d5-b273-95b1f51c6f09" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_med_GrantedIn2020Member_135599fe-8ff1-4a19-8e51-66d87813b434" xlink:href="med-20220930.xsd#med_GrantedIn2020Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_f0710092-d33b-4aa9-94ad-b25c600f81f4" xlink:to="loc_med_GrantedIn2020Member_135599fe-8ff1-4a19-8e51-66d87813b434" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_med_GrantedIn2019Member_225ff279-7871-41d6-8ff3-7e704bee4f8c" xlink:href="med-20220930.xsd#med_GrantedIn2019Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_f0710092-d33b-4aa9-94ad-b25c600f81f4" xlink:to="loc_med_GrantedIn2019Member_225ff279-7871-41d6-8ff3-7e704bee4f8c" xlink:type="arc" order="3"/>
</link:definitionLink>
<link:roleRef roleURI="http://www.medifast1.com/role/LEASESNarrativeDetails" xlink:type="simple" xlink:href="med-20220930.xsd#LEASESNarrativeDetails"/>
<link:definitionLink xlink:role="http://www.medifast1.com/role/LEASESNarrativeDetails" xlink:type="extended" id="i2c3208c7578b4c75a6f22c910322c078_LEASESNarrativeDetails">
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_f281a03b-d7cc-498f-817e-a5f1178e2a88" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_d4f99609-e577-4d48-a0cc-d9fdc1ffa8c6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_f281a03b-d7cc-498f-817e-a5f1178e2a88" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_d4f99609-e577-4d48-a0cc-d9fdc1ffa8c6" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseExpense_d4bbebef-ad73-493f-9218-4736c921b383" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseExpense"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_f281a03b-d7cc-498f-817e-a5f1178e2a88" xlink:to="loc_us-gaap_OperatingLeaseExpense_d4bbebef-ad73-493f-9218-4736c921b383" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_a2a36be5-921c-4f6e-9593-482cbd8d5ce3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_f281a03b-d7cc-498f-817e-a5f1178e2a88" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_a2a36be5-921c-4f6e-9593-482cbd8d5ce3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_ceab0b8f-7c76-4424-8b55-96c11a184733" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_a2a36be5-921c-4f6e-9593-482cbd8d5ce3" xlink:to="loc_srt_RangeAxis_ceab0b8f-7c76-4424-8b55-96c11a184733" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ceab0b8f-7c76-4424-8b55-96c11a184733_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_ceab0b8f-7c76-4424-8b55-96c11a184733" xlink:to="loc_srt_RangeMember_ceab0b8f-7c76-4424-8b55-96c11a184733_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_05f000c3-caa5-4ec5-a30a-db482c9d1509" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_ceab0b8f-7c76-4424-8b55-96c11a184733" xlink:to="loc_srt_RangeMember_05f000c3-caa5-4ec5-a30a-db482c9d1509" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_1985a2e7-5817-42b5-8c90-ea5f2cae5c71" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_05f000c3-caa5-4ec5-a30a-db482c9d1509" xlink:to="loc_srt_MinimumMember_1985a2e7-5817-42b5-8c90-ea5f2cae5c71" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_af3fa3e0-ef5b-4ee2-8257-3f9827379b25" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_05f000c3-caa5-4ec5-a30a-db482c9d1509" xlink:to="loc_srt_MaximumMember_af3fa3e0-ef5b-4ee2-8257-3f9827379b25" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_06efee69-f1fd-43e5-a620-2d7a28e4ccb1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TypeOfArrangementAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_a2a36be5-921c-4f6e-9593-482cbd8d5ce3" xlink:to="loc_us-gaap_TypeOfArrangementAxis_06efee69-f1fd-43e5-a620-2d7a28e4ccb1" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_06efee69-f1fd-43e5-a620-2d7a28e4ccb1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_06efee69-f1fd-43e5-a620-2d7a28e4ccb1" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_06efee69-f1fd-43e5-a620-2d7a28e4ccb1_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_d2cf44f0-de7b-4c72-bce7-11cc0c75d8c8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_06efee69-f1fd-43e5-a620-2d7a28e4ccb1" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_d2cf44f0-de7b-4c72-bce7-11cc0c75d8c8" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_med_OperatingLeaseArrangementForRealEstateMember_d37313c5-4809-4bc7-adce-877787f4e259" xlink:href="med-20220930.xsd#med_OperatingLeaseArrangementForRealEstateMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_d2cf44f0-de7b-4c72-bce7-11cc0c75d8c8" xlink:to="loc_med_OperatingLeaseArrangementForRealEstateMember_d37313c5-4809-4bc7-adce-877787f4e259" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_med_OperatingLeaseArrangementForEquipmentMember_0dcd464d-ea9d-4bf6-a905-157d14c46500" xlink:href="med-20220930.xsd#med_OperatingLeaseArrangementForEquipmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_d2cf44f0-de7b-4c72-bce7-11cc0c75d8c8" xlink:to="loc_med_OperatingLeaseArrangementForEquipmentMember_0dcd464d-ea9d-4bf6-a905-157d14c46500" xlink:type="arc" order="1"/>
</link:definitionLink>
<link:roleRef roleURI="http://www.medifast1.com/role/ACCUMULATEDOTHERCOMPREHENSIVEINCOMEAccumulatedOtherComprehensiveIncomeDetails" xlink:type="simple" xlink:href="med-20220930.xsd#ACCUMULATEDOTHERCOMPREHENSIVEINCOMEAccumulatedOtherComprehensiveIncomeDetails"/>
<link:definitionLink xlink:role="http://www.medifast1.com/role/ACCUMULATEDOTHERCOMPREHENSIVEINCOMEAccumulatedOtherComprehensiveIncomeDetails" xlink:type="extended" id="i917708d4047d4d5499feb7a7854dbdbc_ACCUMULATEDOTHERCOMPREHENSIVEINCOMEAccumulatedOtherComprehensiveIncomeDetails">
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_fb07f6b3-61da-47d2-8e4c-c61a6d396b99" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_d95bbc9b-d05a-416a-8f26-5722195f01dd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_fb07f6b3-61da-47d2-8e4c-c61a6d396b99" xlink:to="loc_us-gaap_StockholdersEquity_d95bbc9b-d05a-416a-8f26-5722195f01dd" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_74b955b7-f0a3-4795-badd-9b267c45b05f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_fb07f6b3-61da-47d2-8e4c-c61a6d396b99" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_74b955b7-f0a3-4795-badd-9b267c45b05f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_32268cc3-2feb-43f6-8f7f-a17f77886644" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_74b955b7-f0a3-4795-badd-9b267c45b05f" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_32268cc3-2feb-43f6-8f7f-a17f77886644" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_32268cc3-2feb-43f6-8f7f-a17f77886644_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_32268cc3-2feb-43f6-8f7f-a17f77886644" xlink:to="loc_us-gaap_EquityComponentDomain_32268cc3-2feb-43f6-8f7f-a17f77886644_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_fb616758-f139-4449-8177-d85e17bda034" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_32268cc3-2feb-43f6-8f7f-a17f77886644" xlink:to="loc_us-gaap_EquityComponentDomain_fb616758-f139-4449-8177-d85e17bda034" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_ad5d6c7d-3383-4ce7-a3d0-66a71e9c4fa6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_fb616758-f139-4449-8177-d85e17bda034" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_ad5d6c7d-3383-4ce7-a3d0-66a71e9c4fa6" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_b7ba1e98-8e8b-4e0c-ab3a-6f4bda0e8dc3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_fb616758-f139-4449-8177-d85e17bda034" xlink:to="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_b7ba1e98-8e8b-4e0c-ab3a-6f4bda0e8dc3" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_3beed3d5-ed0e-45fe-95da-af4a87a58634" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_fb616758-f139-4449-8177-d85e17bda034" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_3beed3d5-ed0e-45fe-95da-af4a87a58634" xlink:type="arc" order="2"/>
</link:definitionLink>
<link:roleRef roleURI="http://www.medifast1.com/role/FINANCIALINSTRUMENTSCashandFinancialAssetsThatareMeasuredatFairValueonaRecurringBasisforEachoftheHierarchyLevelsDetails" xlink:type="simple" xlink:href="med-20220930.xsd#FINANCIALINSTRUMENTSCashandFinancialAssetsThatareMeasuredatFairValueonaRecurringBasisforEachoftheHierarchyLevelsDetails"/>
<link:definitionLink xlink:role="http://www.medifast1.com/role/FINANCIALINSTRUMENTSCashandFinancialAssetsThatareMeasuredatFairValueonaRecurringBasisforEachoftheHierarchyLevelsDetails" xlink:type="extended" id="i32d27d156b0b4ef4918fe91fa8a5b8fa_FINANCIALINSTRUMENTSCashandFinancialAssetsThatareMeasuredatFairValueonaRecurringBasisforEachoftheHierarchyLevelsDetails">
<link:loc xlink:type="locator" xlink:label="loc_med_CashAndCashEquivalentsAndMarketableSecuritiesLineItems_1ccd2367-5759-4dec-a896-6cfbbb4d1f4d" xlink:href="med-20220930.xsd#med_CashAndCashEquivalentsAndMarketableSecuritiesLineItems"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecurities_2ead12ab-bb2d-4b83-8d01-fb85647b9843" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecurities"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_med_CashAndCashEquivalentsAndMarketableSecuritiesLineItems_1ccd2367-5759-4dec-a896-6cfbbb4d1f4d" xlink:to="loc_us-gaap_MarketableSecurities_2ead12ab-bb2d-4b83-8d01-fb85647b9843" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesUnrealizedGainLoss_2fec9145-112d-428c-9b45-3ee67ea597f0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MarketableSecuritiesUnrealizedGainLoss"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_med_CashAndCashEquivalentsAndMarketableSecuritiesLineItems_1ccd2367-5759-4dec-a896-6cfbbb4d1f4d" xlink:to="loc_us-gaap_MarketableSecuritiesUnrealizedGainLoss_2fec9145-112d-428c-9b45-3ee67ea597f0" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestReceivable_c2b5e3d0-af3e-4258-ad3a-c8ef8daf9d36" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestReceivable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_med_CashAndCashEquivalentsAndMarketableSecuritiesLineItems_1ccd2367-5759-4dec-a896-6cfbbb4d1f4d" xlink:to="loc_us-gaap_InterestReceivable_c2b5e3d0-af3e-4258-ad3a-c8ef8daf9d36" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_5d0a9090-a3cf-4691-a79e-c3a60a0a6088" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_med_CashAndCashEquivalentsAndMarketableSecuritiesLineItems_1ccd2367-5759-4dec-a896-6cfbbb4d1f4d" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent_5d0a9090-a3cf-4691-a79e-c3a60a0a6088" xlink:type="arc" order="3"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_0bd050d9-3bd2-47c8-ada4-3e4d0ddd8fd4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_med_CashAndCashEquivalentsAndMarketableSecuritiesLineItems_1ccd2367-5759-4dec-a896-6cfbbb4d1f4d" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_0bd050d9-3bd2-47c8-ada4-3e4d0ddd8fd4" xlink:type="arc" order="4"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedAtFairValue_f6f7e6ae-3e53-4523-a3c4-6aa87855591c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InvestmentOwnedAtFairValue"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_med_CashAndCashEquivalentsAndMarketableSecuritiesLineItems_1ccd2367-5759-4dec-a896-6cfbbb4d1f4d" xlink:to="loc_us-gaap_InvestmentOwnedAtFairValue_f6f7e6ae-3e53-4523-a3c4-6aa87855591c" xlink:type="arc" order="5"/>
<link:loc xlink:type="locator" xlink:label="loc_med_CashAndCashEquivalentsAndMarketableSecuritiesTable_a3e13023-dd38-4c02-967c-4fe26390fb63" xlink:href="med-20220930.xsd#med_CashAndCashEquivalentsAndMarketableSecuritiesTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_med_CashAndCashEquivalentsAndMarketableSecuritiesLineItems_1ccd2367-5759-4dec-a896-6cfbbb4d1f4d" xlink:to="loc_med_CashAndCashEquivalentsAndMarketableSecuritiesTable_a3e13023-dd38-4c02-967c-4fe26390fb63" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_673a1f6c-ee0c-46c4-bd81-18c33f4ae2a7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_med_CashAndCashEquivalentsAndMarketableSecuritiesTable_a3e13023-dd38-4c02-967c-4fe26390fb63" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_673a1f6c-ee0c-46c4-bd81-18c33f4ae2a7" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_673a1f6c-ee0c-46c4-bd81-18c33f4ae2a7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_673a1f6c-ee0c-46c4-bd81-18c33f4ae2a7" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_673a1f6c-ee0c-46c4-bd81-18c33f4ae2a7_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6279e367-b452-459b-9e4d-90e43659dce2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_673a1f6c-ee0c-46c4-bd81-18c33f4ae2a7" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6279e367-b452-459b-9e4d-90e43659dce2" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_e6dccd6f-19d9-4f86-a865-f6a38b5c33b2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6279e367-b452-459b-9e4d-90e43659dce2" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_e6dccd6f-19d9-4f86-a865-f6a38b5c33b2" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_eae59ed8-7cc8-4190-910f-b8d4f2ef7be7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6279e367-b452-459b-9e4d-90e43659dce2" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_eae59ed8-7cc8-4190-910f-b8d4f2ef7be7" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_0f2b2587-7aa0-4f64-b0d8-a5321abf2184" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancialInstrumentAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_med_CashAndCashEquivalentsAndMarketableSecuritiesTable_a3e13023-dd38-4c02-967c-4fe26390fb63" xlink:to="loc_us-gaap_FinancialInstrumentAxis_0f2b2587-7aa0-4f64-b0d8-a5321abf2184" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_0f2b2587-7aa0-4f64-b0d8-a5321abf2184_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_0f2b2587-7aa0-4f64-b0d8-a5321abf2184" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_0f2b2587-7aa0-4f64-b0d8-a5321abf2184_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3bf1d329-37ea-4ae4-8e9e-4e2ad58b7277" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_0f2b2587-7aa0-4f64-b0d8-a5321abf2184" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3bf1d329-37ea-4ae4-8e9e-4e2ad58b7277" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashMember_d4a6b328-2351-4d9f-b903-3b66249bc5d4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3bf1d329-37ea-4ae4-8e9e-4e2ad58b7277" xlink:to="loc_us-gaap_CashMember_d4a6b328-2351-4d9f-b903-3b66249bc5d4" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_92f04c7b-f09f-484a-a676-938d57cfbcd1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MoneyMarketFundsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3bf1d329-37ea-4ae4-8e9e-4e2ad58b7277" xlink:to="loc_us-gaap_MoneyMarketFundsMember_92f04c7b-f09f-484a-a676-938d57cfbcd1" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_med_GovernmentAgencySecuritiesMember_bb827bed-c014-4c3e-80b2-948579ed0282" xlink:href="med-20220930.xsd#med_GovernmentAgencySecuritiesMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3bf1d329-37ea-4ae4-8e9e-4e2ad58b7277" xlink:to="loc_med_GovernmentAgencySecuritiesMember_bb827bed-c014-4c3e-80b2-948579ed0282" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MunicipalBondsMember_353c0e34-bcec-4f4b-a3b9-e88840b7eba5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MunicipalBondsMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3bf1d329-37ea-4ae4-8e9e-4e2ad58b7277" xlink:to="loc_us-gaap_MunicipalBondsMember_353c0e34-bcec-4f4b-a3b9-e88840b7eba5" xlink:type="arc" order="3"/>
</link:definitionLink>
<link:roleRef roleURI="http://www.medifast1.com/role/DEBTNarrativeDetails" xlink:type="simple" xlink:href="med-20220930.xsd#DEBTNarrativeDetails"/>
<link:definitionLink xlink:role="http://www.medifast1.com/role/DEBTNarrativeDetails" xlink:type="extended" id="i7429d91a14ae45e9864406f148ae25bc_DEBTNarrativeDetails">
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_a0eb3c74-d767-474e-925d-642ff66efbc5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_9327221f-fdfb-4906-8957-dae98ed20c37" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a0eb3c74-d767-474e-925d-642ff66efbc5" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_9327221f-fdfb-4906-8957-dae98ed20c37" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_med_LineOfCreditFacilityAccordionFeatureIncreaseLimit_0a84c30e-01a5-4786-933d-de47a7d09a88" xlink:href="med-20220930.xsd#med_LineOfCreditFacilityAccordionFeatureIncreaseLimit"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a0eb3c74-d767-474e-925d-642ff66efbc5" xlink:to="loc_med_LineOfCreditFacilityAccordionFeatureIncreaseLimit_0a84c30e-01a5-4786-933d-de47a7d09a88" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_6a86e507-d7c6-416e-a5f7-518b5c518291" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a0eb3c74-d767-474e-925d-642ff66efbc5" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_6a86e507-d7c6-416e-a5f7-518b5c518291" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_a30ecd40-dfa3-4d16-b9b5-fdc4914927ce" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a0eb3c74-d767-474e-925d-642ff66efbc5" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_a30ecd40-dfa3-4d16-b9b5-fdc4914927ce" xlink:type="arc" order="3"/>
<link:loc xlink:type="locator" xlink:label="loc_med_MaximumTotalNetLeverageRatio_a1190cf0-6820-4db5-81f9-b8909b971d41" xlink:href="med-20220930.xsd#med_MaximumTotalNetLeverageRatio"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a0eb3c74-d767-474e-925d-642ff66efbc5" xlink:to="loc_med_MaximumTotalNetLeverageRatio_a1190cf0-6820-4db5-81f9-b8909b971d41" xlink:type="arc" order="4"/>
<link:loc xlink:type="locator" xlink:label="loc_med_MinimumInterestCoverageRatio_2de422a4-aeff-4537-90aa-3073d6e1f760" xlink:href="med-20220930.xsd#med_MinimumInterestCoverageRatio"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a0eb3c74-d767-474e-925d-642ff66efbc5" xlink:to="loc_med_MinimumInterestCoverageRatio_2de422a4-aeff-4537-90aa-3073d6e1f760" xlink:type="arc" order="5"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_b9ffa807-b70a-4253-bcdc-e6a633762d18" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a0eb3c74-d767-474e-925d-642ff66efbc5" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_b9ffa807-b70a-4253-bcdc-e6a633762d18" xlink:type="arc" order="6"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_0f9359cb-76e4-443a-a8d0-dde02c81f464" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentTable"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a0eb3c74-d767-474e-925d-642ff66efbc5" xlink:to="loc_us-gaap_DebtInstrumentTable_0f9359cb-76e4-443a-a8d0-dde02c81f464" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_3d3a3a9c-a0f3-4a71-ac43-bf1d01c98547" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0f9359cb-76e4-443a-a8d0-dde02c81f464" xlink:to="loc_us-gaap_DebtInstrumentAxis_3d3a3a9c-a0f3-4a71-ac43-bf1d01c98547" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_3d3a3a9c-a0f3-4a71-ac43-bf1d01c98547_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_3d3a3a9c-a0f3-4a71-ac43-bf1d01c98547" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_3d3a3a9c-a0f3-4a71-ac43-bf1d01c98547_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_d58942d8-a33e-4150-b5bb-936515ad277f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_3d3a3a9c-a0f3-4a71-ac43-bf1d01c98547" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_d58942d8-a33e-4150-b5bb-936515ad277f" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_med_CreditAgreementMember_ff2a434e-b4a2-477c-82b8-3b7935522b54" xlink:href="med-20220930.xsd#med_CreditAgreementMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_d58942d8-a33e-4150-b5bb-936515ad277f" xlink:to="loc_med_CreditAgreementMember_ff2a434e-b4a2-477c-82b8-3b7935522b54" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_e6024451-eaf5-4498-b674-d47e47d0e499" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0f9359cb-76e4-443a-a8d0-dde02c81f464" xlink:to="loc_us-gaap_CreditFacilityAxis_e6024451-eaf5-4498-b674-d47e47d0e499" xlink:type="arc" order="2"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_e6024451-eaf5-4498-b674-d47e47d0e499_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_e6024451-eaf5-4498-b674-d47e47d0e499" xlink:to="loc_us-gaap_CreditFacilityDomain_e6024451-eaf5-4498-b674-d47e47d0e499_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_4b2085b8-0021-490a-97e4-74e118d08660" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_e6024451-eaf5-4498-b674-d47e47d0e499" xlink:to="loc_us-gaap_CreditFacilityDomain_4b2085b8-0021-490a-97e4-74e118d08660" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_f117ef77-fc2a-4ce3-a59e-f93a07ace0ad" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_4b2085b8-0021-490a-97e4-74e118d08660" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_f117ef77-fc2a-4ce3-a59e-f93a07ace0ad" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_71755f66-e0ae-4bdd-ae8c-7e41d06614ae" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LetterOfCreditMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevolvingCreditFacilityMember_f117ef77-fc2a-4ce3-a59e-f93a07ace0ad" xlink:to="loc_us-gaap_LetterOfCreditMember_71755f66-e0ae-4bdd-ae8c-7e41d06614ae" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_58c4c904-1768-4e17-b078-a16e1dc51d99" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0f9359cb-76e4-443a-a8d0-dde02c81f464" xlink:to="loc_srt_RangeAxis_58c4c904-1768-4e17-b078-a16e1dc51d99" xlink:type="arc" order="3"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_58c4c904-1768-4e17-b078-a16e1dc51d99_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_58c4c904-1768-4e17-b078-a16e1dc51d99" xlink:to="loc_srt_RangeMember_58c4c904-1768-4e17-b078-a16e1dc51d99_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_73b4c742-144f-41a8-a06e-31bc3fc5e55a" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_58c4c904-1768-4e17-b078-a16e1dc51d99" xlink:to="loc_srt_RangeMember_73b4c742-144f-41a8-a06e-31bc3fc5e55a" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_02b8f8da-d6e9-4fa5-b287-929eefa45246" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_73b4c742-144f-41a8-a06e-31bc3fc5e55a" xlink:to="loc_srt_MinimumMember_02b8f8da-d6e9-4fa5-b287-929eefa45246" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_c6757186-7799-44c7-a8bc-4c00b5c1aa0f" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_73b4c742-144f-41a8-a06e-31bc3fc5e55a" xlink:to="loc_srt_MaximumMember_c6757186-7799-44c7-a8bc-4c00b5c1aa0f" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_672fac94-c9f4-4e4a-8c4e-84fc49ce1b26" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateAxis"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0f9359cb-76e4-443a-a8d0-dde02c81f464" xlink:to="loc_us-gaap_VariableRateAxis_672fac94-c9f4-4e4a-8c4e-84fc49ce1b26" xlink:type="arc" order="4"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_672fac94-c9f4-4e4a-8c4e-84fc49ce1b26_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_672fac94-c9f4-4e4a-8c4e-84fc49ce1b26" xlink:to="loc_us-gaap_VariableRateDomain_672fac94-c9f4-4e4a-8c4e-84fc49ce1b26_default" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_166c9d39-f4c0-461a-9200-3144cc6cab1e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateDomain"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_672fac94-c9f4-4e4a-8c4e-84fc49ce1b26" xlink:to="loc_us-gaap_VariableRateDomain_166c9d39-f4c0-461a-9200-3144cc6cab1e" xlink:type="arc" order="1"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EurodollarMember_b49ad755-dbd7-4089-bb69-1a36db45329f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EurodollarMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_166c9d39-f4c0-461a-9200-3144cc6cab1e" xlink:to="loc_us-gaap_EurodollarMember_b49ad755-dbd7-4089-bb69-1a36db45329f" xlink:type="arc" order="0"/>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_301c69dc-f3fe-4e3a-b2d7-623a94995ec2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BaseRateMember"/>
<link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_166c9d39-f4c0-461a-9200-3144cc6cab1e" xlink:to="loc_us-gaap_BaseRateMember_301c69dc-f3fe-4e3a-b2d7-623a94995ec2" xlink:type="arc" order="1"/>
</link:definitionLink>
</link:linkbase>


2 Previous Filings that this Filing References

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

12/04/19  Medifast Inc.                     8-K/A:9     6/12/19   11:412K                                   Toppan Merrill/FA
 2/27/15  Medifast Inc.                     8-K:5,9     2/17/15    4:89K                                    Toppan Merrill/FA
Top
Filing Submission 0001628280-22-028255   –   Alternative Formats (Word / Rich Text, HTML, Plain Text, et al.)

Copyright © 2024 Fran Finnegan & Company LLC – All Rights Reserved.
AboutPrivacyRedactionsHelp — Fri., May 3, 8:58:34.2pm ET