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What the GLP‑1 trials found

Pick a medicine and dose to see its main trial as the UK label reports it: average weight change, how many people reached 5, 10, 15 or 20%, and the side effects and stopping rates beside them.

Nothing you enter leaves your device Every number cites its label section
Trial averages, not a prediction for you. This doesn't replace the label or your prescriber. Some people lose much more than the average and some lose very little. Talk to your GP or prescriber before starting, stopping or changing a medicine.Information only, not a promotion. Every medicine named here is prescription-only. Only a GP can decide whether one is right for you and prescribe it. We don't recommend, rank or favour any medicine. Where we list several, they're in alphabetical order. We don't sell medicines or take money from drug companies.

Pick a medicine and dose

Medicine
kg

Shows what the trial's averages and proportions would mean in kilograms, with stones and pounds. Not a prediction.

How these trials work
  • People were put into groups by chance: one got the medicine, one got a placebo (a dummy injection or dummy tablet with no medicine in it).
  • Both groups got the same diet and activity advice.
  • The gap between the two groups is what the medicine added.
These trials can't be ranked against each other. They had different people, lengths, doses and diet advice, ran at different times, and the UK labels don't all analyse them the same way. Only a head-to-head trial tests two medicines in the same trial: see Compare.

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How this works

For each medicine we use the main trial in its UK label, the summary of product characteristics (SmPC) published on the electronic Medicines Compendium: section 5.1 for the trial results and section 4.8 for side effects. Section 4.8 often pools several trials and sometimes gives no placebo figure; the card says which trials and leaves out any number the label doesn't give. Where the label has no figure for that trial alone, we use the published trial paper and say so. Every number sits in one data block on this page with its source.

"Average" weight change is the mean for the whole group. The share who reached at least 5, 10, 15 or 20% shows the spread: it's a range, not one number. If you enter your weight, we multiply it by the same percentages. That's arithmetic on trial averages, not a forecast.

Ozempic and Rybelsus are licensed in the UK for type 2 diabetes only, not for weight loss. Their labels report weight change from diabetes trials in kilograms only, so we show that and nothing more.

What this can't tell you

  • How much you will lose. Your result depends on you, your dose and how long you take it, and isn't predicted by a trial average.
  • Which medicine works more. Separate trials can't be ranked.
  • What happens after stopping. Weight usually comes back in part: see Stopping and the long term.
  • Rare or long-term risks. Those are in each label's section 4.4 and 4.8, and in Side effects and risks. To report a side effect, use the MHRA Yellow Card scheme.16

Questions people ask

Can I compare the numbers for different medicines?

No. Each trial had different people, lengths, doses and diet advice, and the UK labels don't all analyse their trials the same way, so the numbers can't be ranked against each other. Only a head-to-head trial, where both medicines are tested in the same trial, can compare them.

Is this how much weight I will lose?

No. These are trial averages, not a prediction for you. In every trial some people lost much more than the average and some lost very little. That's why the tool shows how many people reached each amount, not one number.

What is a placebo?

A dummy injection or dummy tablet with no medicine in it. In these trials people were put into groups by chance, and both groups got the same diet and activity advice. The gap between the medicine group and the dummy group is what the medicine added.

Why are Ozempic and Rybelsus shown differently?

In the UK they're licensed for type 2 diabetes only, not for weight loss. Their labels report weight change from diabetes trials in kilograms, and not how many people lost 5% or more, so the tool shows only the average change for them.

Why are some numbers missing?

We only show a number that the UK label or the trial's own paper gives. Where neither gives it, for example a placebo figure for some side effects, we leave it out instead of estimating it, and the card says so.

Is anything I enter saved or sent?

No. The weight you enter is used only in your browser to turn the trial percentages into kilograms. Nothing is sent or stored.

Sources

  1. Novo Nordisk. Wegovy 2.4 mg FlexTouch solution for injection in pre-filled pen: summary of product characteristics (SmPC), UK label, revised 09/2026. Section 5.1 (Table 4: STEP 1; Table 12: STEP UP and its footnotes) and 4.8 (gastrointestinal adverse reactions, dysaesthesia). SmPC on emc. Checked 14 Oct 2026.
  2. Novo Nordisk. Wegovy tablets: SmPC, UK label, revised 06/2026. Section 5.1 (Table 2: OASIS 4) and 4.8 (gastrointestinal adverse reactions in OASIS 4). SmPC on emc. Checked 14 Oct 2026.
  3. Eli Lilly. Mounjaro KwikPen: SmPC, UK label, revised 29 August 2026. Section 5.1 (Table 9: SURMOUNT-1, efficacy estimand) and 4.8 (gastrointestinal adverse reactions, SURMOUNT-1 and -2 pooled). SmPC on emc. Checked 14 Oct 2026.
  4. Novo Nordisk. Saxenda 6 mg/ml solution for injection: SmPC, UK label, revised 11/2025. Section 5.1 (Table 4: Trial 1, SCALE Obesity and Prediabetes, last observation carried forward) and 4.8 (summary and Table 3 frequencies). SmPC on emc. Checked 14 Oct 2026.
  5. Eli Lilly. Foundayo film-coated tablets: SmPC, UK label, revised 10 August 2026. Section 5.1 (Table 2: tablet and capsule doses of equal effect; Table 3: ATTAIN-1) and 4.8 (Table of adverse reactions; gastrointestinal adverse reactions in the weight management phase 3 studies). SmPC on emc. Checked 14 Oct 2026.
  6. Novo Nordisk. Ozempic solution for injection in pre-filled pen: SmPC, UK label, revised 07/2026. Section 5.1 (Table 2: SUSTAIN 1) and 4.8 (gastrointestinal adverse reactions; discontinuation due to an adverse event). SmPC on emc. Checked 14 Oct 2026.
  7. Novo Nordisk. Rybelsus 3 mg, 7 mg and 14 mg tablets: SmPC, UK label, revised 03/2026. Section 5.1 (Table 2: PIONEER 1) and 4.8 (gastrointestinal adverse reactions). SmPC on emc. Checked 14 Oct 2026.
  8. Novo Nordisk. Rybelsus 1.5 mg, 4 mg and 9 mg tablets: SmPC, UK label, revised 03/2026. Section 5.1 (PIONEER 1: 7 mg and 14 mg are bioequivalent to 4 mg and 9 mg). SmPC on emc. Checked 14 Oct 2026.
  9. Wilding JPH et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med 2021;384:989-1002. PMID 33567185. Abstract: stopped because of gastrointestinal events 4.5% vs 0.8%. Funded by Novo Nordisk. PubMed. Checked 14 Oct 2026.
  10. Once-weekly semaglutide 7.2 mg in adults with obesity (STEP UP): a randomised, controlled, phase 3b trial. Lancet Diabetes Endocrinol 2025;13:949-963. PMID 40961952. Abstract: 7.2 mg vs placebo −18.7% vs −3.9%, estimated difference −14.8 percentage points. Funded by Novo Nordisk. PubMed. Checked 14 Oct 2026.
  11. Wharton S et al. Oral semaglutide at a dose of 25 mg in adults with overweight or obesity (OASIS 4). N Engl J Med 2025;393:1077-1087. PMID 40934115. Funded by Novo Nordisk. PubMed. Checked 14 Oct 2026.
  12. Jastreboff AM et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med 2022;387:205-216. PMID 35658024. Supported by Eli Lilly. PubMed. Checked 14 Oct 2026.
  13. Pi-Sunyer X et al. A randomized, controlled trial of 3.0 mg of liraglutide in weight management (SCALE Obesity and Prediabetes). N Engl J Med 2015;373:11-22. PMID 26132939. Abstract: serious events 6.2% vs 5.0%. Funded by Novo Nordisk. PubMed. Checked 14 Oct 2026.
  14. Orforglipron, an oral small-molecule GLP-1 receptor agonist for obesity treatment (ATTAIN-1). N Engl J Med 2025;393:1796-1806. PMID 40960239. Doses 6, 12 and 36 mg of the capsule used in the trial. Funded by Eli Lilly. PubMed. Checked 14 Oct 2026.
  15. Sorli C et al. Efficacy and safety of once-weekly semaglutide monotherapy versus placebo in patients with type 2 diabetes (SUSTAIN 1). Lancet Diabetes Endocrinol 2017;5:251-260. PMID 28110911. Funding: Novo Nordisk. PubMed. Checked 14 Oct 2026.
  16. MHRA. Yellow Card scheme: report a suspected side effect. yellowcard.mhra.gov.uk. Checked 14 Oct 2026.
  17. PIONEER 1 (NCT02906930), ClinicalTrials.gov record: lead sponsor Novo Nordisk A/S. Aroda VR et al. Diabetes Care 2019;42:1724-1732, PMID 31186300. ClinicalTrials.gov. Checked 14 Oct 2026.

Last checked 14 Oct 2026 · Next review due 14 Jan 2027

How this tool was made. Written by the GLP Guidebook team from the UK labels and trial papers above, each opened and checked. The trials were paid for by the makers of the medicines (Novo Nordisk or Eli Lilly). It's general information, not medical advice, and it doesn't replace the label or your prescriber. Talk to your GP or another qualified prescriber before starting, stopping or changing any medicine. In an emergency, call 999; if you're not sure, call NHS 111. How we write