<SEC-DOCUMENT>0001144204-17-010267.txt : 20170221
<SEC-HEADER>0001144204-17-010267.hdr.sgml : 20170221
<ACCEPTANCE-DATETIME>20170221195759
ACCESSION NUMBER:		0001144204-17-010267
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170216
FILED AS OF DATE:		20170221
DATE AS OF CHANGE:		20170221

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:			KELLEMAN JOSEPH P
		CENTRAL INDEX KEY:			0001629239

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-31573
		FILM NUMBER:		17626771

	MAIL ADDRESS:	
		STREET 1:		3600 CRONDALL LANE
		CITY:			OWINGS MILLS
		STATE:			MD
		ZIP:			21117
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>v460105_4.xml
<DESCRIPTION>OWNERSHIP DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-02-16</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000910329</issuerCik>
        <issuerName>MEDIFAST INC</issuerName>
        <issuerTradingSymbol>MED</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001629239</rptOwnerCik>
            <rptOwnerName>KELLEMAN JOSEPH P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MEDIFAST, INC.,</rptOwnerStreet1>
            <rptOwnerStreet2>3600 CRONDALL LANE</rptOwnerStreet2>
            <rptOwnerCity>OWINGS MILLS</rptOwnerCity>
            <rptOwnerState>MD</rptOwnerState>
            <rptOwnerZipCode>21117</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Vice President of Finance</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>44.73</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-02-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1250</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2027-02-16</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1250</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1250</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">These non qualified stock options, which were issued to the reporting person under the 2012 Share Incentive Plan, will vest in three equal annual installments beginning on the first anniversary of the grant date.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Joseph P. Kelleman</signatureName>
        <signatureDate>2017-02-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
