Medifast makes no claim that these results are representative of all participants on the Medifast Program. Medifast recommends you consult with a physician before starting a weight-loss program. Medifast is the brand recommended by more than 20,000 doctors since 1980. Results vary. Clients can expect to lose 2-5 lbs per week for the first 2 weeks, and 1-2 lbs per week thereafter on the Medifast 5 & 1 Plan.