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-K for the year ended December 31, 2012 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 of the Company, 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
Chairman of the Board and Chief Executive Officer
March 15, 2013
By:	/s/ Timothy G. Robinson
Timothy G. Robinson
Chief Financial Officer
March 15, 2013