SemaglutideGLP-1 medicine for weight loss

What is Semaglutide?

Semaglutide is a GLP-1 receptor agonist. The EU product Wegovy is used for weight management in adults meeting specified obesity or overweight criteria, alongside diet and physical activity. 1

How it works

GLP-1 receptor activation influences appetite and fullness, helping reduce food intake. The clinical effect depends on the product, population and continuing treatment. 1

Effects studied

Labels: Proven = consistent results in good human trials. Mixed = results point in different directions. Not shown = tested in people without a clear effect, or only in uncontrolled reports. Lab & animal only = no human evidence yet.

What does the evidence show?

Phase 3 placebo-controlled trial and direct randomised comparison

The useful question is about a medicine

Semaglutide’s evidence concerns an authorised prescription medicine for weight management, assessed alongside lifestyle support. It cannot establish that peptides as a group work, and it is not a nutrient everyone needs. The treatment, patient group and outcome define what the research can tell us.

EMA describes semaglutide as a GLP-1 receptor agonist, acting on appetite and fullness. Wegovy's EU indication includes adults with obesity, or overweight with specified weight-related health problems. The current product information, rather than a generic peptide label, defines its use. 1

A trial large enough to estimate an average effect

STEP 1 enrolled 1,961 adults with overweight or obesity who did not have diabetes. After 68 weeks, average body-weight change was −14.9% with semaglutide and −2.4% with placebo; both groups received lifestyle intervention. The estimated difference was −12.4 percentage points (95% CI −13.4 to −11.5). Novo Nordisk funded the study. 2

These are group averages, not a prediction for one person. The trial also used a defined formulation and protocol. It does not establish equivalence for every product advertised using the same ingredient name.

STEP 1 tested a weekly 2.4 mg subcutaneous injection. Its results should not be assigned to another dose or an oral formulation. 2

Read the benefit beside the tolerability result

In STEP 1, nausea and diarrhoea were common, and 4.5% of semaglutide participants stopped treatment because of gastrointestinal events, compared with 0.8% on placebo. 2 EMA's product information sets out the broader warnings, contraindications and follow-up considerations. 1

Persistent severe abdominal pain needs urgent assessment for pancreatitis. Vomiting or diarrhoea can cause dehydration and worsen kidney function. Tell the anaesthesia team about semaglutide before surgery or deep sedation because it delays stomach emptying. Sudden loss of vision needs urgent eye assessment; treatment must be stopped if NAION is confirmed. 4

UK MHRA advice is to stop semaglutide at least two months before trying to become pregnant. Discuss a treatment plan with the prescriber. 5

What people mean by less “food noise”

The INFORM survey asked 550 US users of injectable semaglutide about persistent thoughts about food. Participants reported less of this “food noise” after starting treatment. That describes an experience worth discussing, but the survey relied on recalled earlier symptoms and had no untreated comparison group. It cannot separate a drug effect from expectations, weight loss or who chose to respond. Several authors worked for Novo Nordisk. 6

Where this fits in a peptide library

SURMOUNT-5 directly compared the two medicines in 751 adults with obesity and without type 2 diabetes. In this open-label trial, weight fell by an average of 20.2% with tirzepatide and 13.7% with semaglutide at 72 weeks. Participants received their maximum tolerated weekly injection dose: tirzepatide 10 or 15 mg, or semaglutide 1.7 or 2.4 mg. Eli Lilly funded the trial. 3

That comparison favoured tirzepatide for weight loss at the tested doses. It does not show that it is better for every patient, every dose or cardiovascular outcomes. 3

Safety & status

Nausea and diarrhoea were common. Gastrointestinal events led to discontinuation in 4.5% of semaglutide participants and 0.8% of placebo participants. The product information covers additional risks and suitability criteria. 1 2

Persistent severe abdominal pain needs urgent assessment for pancreatitis. Vomiting or diarrhoea can cause dehydration and worsen kidney function. Tell the anaesthesia team about semaglutide before surgery or deep sedation because it delays stomach emptying. Sudden loss of vision needs urgent eye assessment; treatment must be stopped if NAION is confirmed. 4

UK MHRA advice is to stop semaglutide at least two months before trying to become pregnant. Discuss a treatment plan with the prescriber. 5

Related names & questions

Connections help distinguish compounds and uses; they do not imply equivalent benefits.