Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO 

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Annual Report of Medifast, Inc. (the “Company”) on Form 10-Q for the quarter ended September 30, 2013, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Michael C. MacDonald, Chief Executive Officer and I, Timothy G. Robinson, Chief Financial Officer, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, to the best of my knowledge, that:

(1) The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and

(2) The information contained in the report fairly presents, in all material respects, the financial condition and results of the operations of the Company.

By:	/s/ Michael C. MacDonald
	Michael C. MacDonald
	Chief Executive Officer
	November 12, 2013
By:	/s/ Timothy G. Robinson
	Timothy G. Robinson
	Chief Financial Officer
	November 12, 2013