Semaglutide
Semaglutide is a long-acting GLP-1 receptor agonist developed by Novo Nordisk and FDA-approved under three brand names: Ozempic (subcutaneous, type 2 diabetes), Wegovy (subcutaneous, chronic weight management), and Rybelsus (oral, type 2 diabetes). It is administered as a once-weekly injection at doses ranging from 0.25 mg to 2.4 mg.
What is semaglutide?
Semaglutide is a long-acting GLP-1 receptor agonist developed by Novo Nordisk. It was structurally engineered for resistance to enzymatic degradation, giving it a half-life of approximately one week — long enough for once-weekly subcutaneous dosing. Three FDA-approved brands deliver semaglutide:
- Ozempic — subcutaneous injection 0.25-2 mg/week, FDA-approved for type 2 diabetes (2017)
- Wegovy — subcutaneous injection 0.25-2.4 mg/week, FDA-approved for chronic weight management (2021)
- Rybelsus — oral tablet 3-14 mg/day, FDA-approved for type 2 diabetes (2019)
How does semaglutide work?
Semaglutide activates the GLP-1 receptor with effects characteristic of the class:
- Glucose-dependent insulin secretion and glucagon suppression
- Slowed gastric emptying
- Central appetite suppression via hypothalamic GLP-1 receptors
Pivotal weight management evidence comes from the STEP clinical trial program. Wilding et al., 2021, NEJM (STEP 1) reported a mean weight loss of approximately 14.9% of baseline body weight over 68 weeks at 2.4 mg/week, vs. 2.4% with placebo. Subsequent trials (STEP 2-8) extended evidence across diabetes, cardiovascular risk, and adolescent populations.
Why semaglutide matters for nutrition
Patients on semaglutide typically eat 20-30% fewer calories spontaneously. From a clinical nutrition standpoint, the priorities are:
- Protein adequacy — 1.2-1.6 g/kg/day; aim for protein-forward meals to preserve lean mass
- Hydration and electrolytes — increased risk of GI losses
- Slow titration of food volume — early dosing causes nausea; small frequent meals often better tolerated
- Resistance training — combined with adequate protein, reduces lean mass loss
Common side effects: nausea (up to 44% in trials), vomiting (24%), diarrhea (30%), constipation, abdominal pain. Rare but serious: pancreatitis, gallbladder events, severe gastroparesis. Boxed warning for thyroid C-cell tumors (based on rodent data; human relevance debated).
This is general educational information, not medical advice. Consult your physician before starting, stopping, or adjusting semaglutide. Dosing, side-effect management, and contraindications are decisions for your prescribing clinician.
See Ozempic for brand-specific information, tirzepatide for the dual GLP-1/GIP alternative, and GLP-1 receptor agonist for class context.