What Is Semaglutide?
Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist prescription medication used for type 2 diabetes (Ozempic, Rybelsus) and chronic weight management (Wegovy). It is a modified peptide that mimics the incretin hormone GLP-1, enhancing glucose-dependent insulin secretion, slowing gastric emptying, and reducing appetite. It is a prescription drug, not a dietary supplement, and this entry is included for reference only. Its efficacy evidence is unusually strong for the encyclopedia — backed by large phase 3 randomised trials.
Evidence
For chronic weight management, the phase 3 STEP 1 randomised placebo-controlled trial (Wilding et al., 2021) reported a mean weight loss of roughly 14.9% over 68 weeks with once-weekly 2.4 mg subcutaneous semaglutide plus lifestyle intervention, versus about 2.4% with placebo 1Reference 1RCTOnce-Weekly Semaglutide in Adults with Overweight or Obesity — randomised controlled trial (STEP 1)View study →. Semaglutide’s mechanism as a GLP-1 receptor agonist — improving glycaemic control and reducing appetite — is well established in the diabetes and obesity literature; the broader SUSTAIN (diabetes) and STEP (obesity) programmes were not individually retrieved and verified in this quick pass and should be added in a full pass. Common adverse effects reported in trials are gastrointestinal (nausea, vomiting, diarrhoea).
Dosage & Safety
Semaglutide is a prescription medicine that is dosed and titrated by a clinician (for weight management, escalated to up to 2.4 mg once weekly by subcutaneous injection 1Reference 1RCTOnce-Weekly Semaglutide in Adults with Overweight or Obesity — randomised controlled trial (STEP 1)View study →); the figures here are informational, not a recommendation, and it must not be self-sourced or self-dosed. It carries a boxed warning regarding thyroid C-cell tumours observed in rodents and is contraindicated in people with a personal or family history of medullary thyroid carcinoma or MEN 2; pancreatitis and gallbladder events have also been reported. Because it is a prescription drug and not an approved dietary supplement, full contraindication, interaction, and pregnancy details are outside the scope of this stub and should be confirmed against the official label in a full pass. Informational only.
References
- Wilding JPH, et al. (2021). Once-Weekly Semaglutide in Adults with Overweight or Obesity — randomised controlled trial (STEP 1). N Engl J Med, 384:989–1002. https://doi.org/10.1056/NEJMoa2032183