Research
Energy balance
Very-low-calorie (VLC) meal replacement programs (HMR, Medifast, OPTIFAST) produce greater short-term weight loss than counseling, but effects attenuate after 6 months and carry risks of gallstones.
VLC programs like HMR, Medifast, and OPTIFAST can help you lose weight quickly (3-6 months) if you are willing to consume 800-1000 calories daily. However, the weight loss may not be sustained after 6 months, and there is a small risk of gallstones. These programs are best used under medical supervision and for short-term goals.
ModerateQualifiesMEDIUM confidence
Very-low-calorie programs (Health Management Resources, Medifast, and OPTIFAST) resulted in at least 4.0% greater short-term weight loss than counseling, but some attenuation of effect occurred beyond 6 months when reported. ... These approaches may also have risks, such as gallstones requiring cholecystectomy.
Why this rating
High ROB in many trials, short duration, attenuation of effect.
Source
Efficacy of Commercial Weight-Loss Programs
Kimberly A. Gudzune et al. · Annals of Internal Medicine · 2015
DOI 10.7326/m14-2238
systematic_reviewCited 331×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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