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 March 31,  2006,  as filed with the  Securities  and
Exchange  Commission on the date hereof (the "Report"),  I Bradley T. MacDonald,
Chief  Executive  Officer  of the  Company  and I  Michael  S.  McDevitt,  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/ Bradley T. MacDonald
   -------------------------
   Bradley T. MacDonald
   Chief Executive Officer
   May15, 2006

By: /s/ Michael S. McDevitt
   ------------------------
   Michael S. McDevitt
   Chief Financial Officer
   May 15, 2006


                                       20