<SEC-DOCUMENT>0001144204-14-009752.txt : 20140214
<SEC-HEADER>0001144204-14-009752.hdr.sgml : 20140214
<ACCEPTANCE-DATETIME>20140214161029
ACCESSION NUMBER:		0001144204-14-009752
CONFORMED SUBMISSION TYPE:	5
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20131231
FILED AS OF DATE:		20140214
DATE AS OF CHANGE:		20140214

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MEDIFAST INC
		CENTRAL INDEX KEY:			0000910329
		STANDARD INDUSTRIAL CLASSIFICATION:	MISCELLANEOUS FOOD PREPARATIONS & KINDRED PRODUCTS [2090]
		IRS NUMBER:				133714405
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		11445 CRONHILL DRIVE
		CITY:			OWINGS MILLS
		STATE:			MD
		ZIP:			21117
		BUSINESS PHONE:		7327640619

	MAIL ADDRESS:	
		STREET 1:		11445 CRONHILL DRIVE
		CITY:			OWINGS MILLS
		STATE:			MD
		ZIP:			21117

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	HEALTHRITE INC
		DATE OF NAME CHANGE:	19951120

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	XX
		DATE OF NAME CHANGE:	19950619

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	00
		DATE OF NAME CHANGE:	19950619

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SHEETZ MARGARET MACDONALD
		CENTRAL INDEX KEY:			0001224955

	FILING VALUES:
		FORM TYPE:		5
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-31573
		FILM NUMBER:		14616380

	MAIL ADDRESS:	
		STREET 1:		9332 OWINGS CHOICE CT
		CITY:			OWINGS MILLS
		STATE:			MD
		ZIP:			21117

	FORMER NAME:	
		FORMER CONFORMED NAME:	MACDONALD MARGARET
		DATE OF NAME CHANGE:	20030328
</SEC-HEADER>
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<TYPE>5
<SEQUENCE>1
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<DESCRIPTION>OWNERSHIP DOCUMENT
<TEXT>
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    <schemaVersion>X0306</schemaVersion>

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    <periodOfReport>2013-12-31</periodOfReport>

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        <issuerName>MEDIFAST INC</issuerName>
        <issuerTradingSymbol>MED</issuerTradingSymbol>
    </issuer>

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            <rptOwnerName>SHEETZ MARGARET MACDONALD</rptOwnerName>
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            <rptOwnerStreet1>C/O MEDIFAST, INC</rptOwnerStreet1>
            <rptOwnerStreet2>11445 CRONHILL DR.</rptOwnerStreet2>
            <rptOwnerCity>OWINGS MILLS</rptOwnerCity>
            <rptOwnerState>MD</rptOwnerState>
            <rptOwnerZipCode>21117</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President &amp; COO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
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                <value>Common Stock</value>
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            </transactionDate>
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            <transactionCoding>
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            <transactionAmounts>
                <transactionShares>
                    <value>16667</value>
                    <footnoteId id="F2"/>
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                <transactionPricePerShare>
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            <transactionDate>
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            <transactionTimeliness>
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                    <footnoteId id="F1"/>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
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            <transactionDate>
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            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
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            <transactionTimeliness>
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                <transactionShares>
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                    <footnoteId id="F1"/>
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                <transactionAcquiredDisposedCode>
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                <sharesOwnedFollowingTransaction>
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            <transactionDate>
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            <transactionTimeliness>
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                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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        </nonDerivativeTransaction>
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            <transactionDate>
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            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
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            <transactionTimeliness>
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                <transactionCode>S</transactionCode>
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                    <value>20000</value>
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                    <value>23.8408</value>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
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                <value>2013-11-22</value>
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            <deemedExecutionDate></deemedExecutionDate>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness>
                <value>L</value>
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                <transactionShares>
                    <value>8000</value>
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                <transactionPricePerShare>
                    <value>26.0054</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
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            <transactionDate>
                <value>2013-12-02</value>
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            <deemedExecutionDate></deemedExecutionDate>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness>
                <value>L</value>
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            <transactionAmounts>
                <transactionShares>
                    <value>18000</value>
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                <transactionPricePerShare>
                    <value>25.6287</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
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                    <footnoteId id="F4"/>
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    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These securities were awarded by the Company in transactions exempt from Section 16(b) of the Exchange Act.</footnote>
        <footnote id="F2">These transactions reflect gifts received by the reporting person, or given by the reporting person, in transactions exempt from Section 16(b) of the Exchange Act.</footnote>
        <footnote id="F3">These transactions were initially reported on a Form 4 filed by the reporting person on November 25, 2013 and are corrected to reflect the amount of shares beneficially owned at fiscal year-end.</footnote>
        <footnote id="F4">These transactions were initially reported on a Form 4 filed by the reporting person on December 4, 2013 and are corrected to reflect the amount of shares beneficially owned at fiscal year-end.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Margaret MacDonald Sheetz</signatureName>
        <signatureDate>2014-02-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</SEC-DOCUMENT>
