GLP-1 receptor agonists mimic an intestinal hormone called glucagon-like peptide-1.
Three weight-loss mechanisms
- Slowed gastric emptying — food stays in your stomach longer, so you feel full sooner.
- Brain satiety signals — GLP-1 acts on the hypothalamus and brainstem to reduce hunger and food-noise.
- Improved insulin sensitivity — modest metabolic effects independent of weight loss.
Expected weight loss
- Wegovy (semaglutide 2.4 mg): about 15% mean body weight over 68 weeks (STEP-1 trial).
- Zepbound (tirzepatide 15 mg): about 22% mean body weight over 72 weeks (SURMOUNT-1 trial).
- Saxenda (liraglutide): about 8% mean body weight over 56 weeks (SCALE trial).
Individual results vary substantially.
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What is the difference between Ozempic and Wegovy?
Both contain semaglutide (Novo Nordisk). Ozempic is FDA-approved for type 2 diabetes; Wegovy is approved for chronic weight management at a higher max dose.
What is the difference between Zepbound and Mounjaro?
Both are tirzepatide (Eli Lilly). Mounjaro is FDA-approved for type 2 diabetes; Zepbound is approved for chronic weight management. Same molecule, same dose.
What is compounded GLP-1 and how is it different?
Compounded GLP-1 is custom-mixed by a 503A or 503B pharmacy. It costs less but is NOT FDA-reviewed for safety or efficacy.