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Why am I not losing weight on Wegovy, Ozempic or Mounjaro?

GLP Guidebook teamUpdated 20 Oct 202613 sourcesWritten from published sources
What we checked13 sources, each one opened and linked to the sentence it supportsLast checked 20 Oct 2026 · Next review due 20 Oct 2027 · How we write
The short answer

Some people lose little on Wegovy (semaglutide), Ozempic or Mounjaro (tirzepatide), and a low early dose, diabetes or other medicines can play a part. In Health Canada’s monographs, about 17 in 100 on Wegovy and 9 to 15 in 100 on Zepbound (tirzepatide) didn’t reach 5% loss; with type 2 diabetes, about 33 in 100 on Wegovy didn’t.

Before you go further
  • GLP‑1 medicines are prescription drugs in Canada. Your prescriber decides your dose.
  • Dose and trial facts here come from Health Canada’s product monographs and Canada’s obesity guideline.
  • We name brands as facts only. Nothing here promises any result, and nothing here is for sale.

How many people lose little on Wegovy or Zepbound?

Most adults in the main trials lost at least 5% of their weight, but a real minority didn’t.1,2

In STEP 1 (68 weeks, adults without diabetes), 83.5% on Wegovy 2.4 mg reached 5%, against 31.1% on a placebo (dummy injection).1 The trial paper, which handles dropouts differently, reports 86.4% against 31.5%.7 In SURMOUNT-1 (72 weeks), 85.1% to 90.9% on Zepbound 5 to 15 mg reached it, against 34.5%.2,8 For a 90 kg (198 lb) person, 5% is 4.5 kg (about 10 lb).

Put the other way, about 17 in 100 on Wegovy and 9 to 15 in 100 on Zepbound didn’t reach 5%.1,2 In STEP 2, with type 2 diabetes, 67.4% reached it, so about 33 in 100 didn’t.1

Average loss with type 2 diabetes was 9.6% on Wegovy and 12.8% to 14.7% on Zepbound.1,2,9,10 Canada’s obesity guideline says response varies a lot (“considerable heterogeneity”). It adds that doctors can’t yet predict which medicine will work best for whom.5 More in Guide 4: what results to expect.

Could it be too early to tell?

Early results can mislead, because each medicine starts on a low dose that rises in steps, after at least 4 weeks on each, so the first months are below the full dose.1,2,3

Canada’s Ozempic monograph says its 0.25 mg starting dose “is not a therapeutic dose”.3 Wegovy reaches its 2.4 mg maintenance dose at week 17.1 Zepbound’s 2.5 mg dose is “for treatment initiation”, and blood levels settle after 4 weeks on a dose.2 In SURMOUNT-1, average loss rose with the dose: 15.0% on 5 mg, 19.5% on 10 mg and 20.9% on 15 mg.2

The guideline says regulators have traditionally used 5% loss after 3 months on a therapeutic dose as the check. It adds that health can improve “regardless of the magnitude of weight loss”.5 Ozempic and Mounjaro are approved in Canada for type 2 diabetes, not for weight management.3,4

See the range of trial results

Weight loss and side effects from the main GLP‑1 trials, side by side.

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What may a doctor look at if it isn’t working?

Canada’s obesity guideline lists what to reassess: the dose, cost, access, taking it as prescribed, barriers to changing habits, and other medical or psychological issues.5

It also says to check other medicines that can add weight.5 Its assessment chapter names insulin, gliclazide and other sulfonylureas, some antidepressants, lithium, antipsychotics such as olanzapine, steroids such as prednisone, and some beta blockers.6 In STEP 1, STEP 2 and SURMOUNT-1, everyone was also taught a reduced-calorie diet, about 500 kcal a day below their needs, plus more activity.1,2 It lists checks for sleep problems, and hormone tests for women with signs of polycystic ovary syndrome (PCOS).6 Screening for thyroid problems isn’t routine unless symptoms point that way.6

If goals aren’t met on the highest dose a person can tolerate, adding or switching to another obesity medicine can be considered.5 In SURMOUNT-5, in 751 adults without diabetes, average loss over 72 weeks was 20.2% on tirzepatide and 13.7% on semaglutide.5,11 If you lost weight and then stopped losing, see why weight loss stalls.

What do people on Wegovy, Ozempic or Mounjaro report about losing little?

From public patient forums: 12 Reddit threads in r/Zepbound, r/Mounjaro, r/OzempicForWeightLoss, r/MounjaroUK, r/WegovyWeightLoss and r/Wegovy, read in October 2026. Personal reports, not medical evidence.

What people describe

  • Matches the label Many say they lost little until a higher dose. Canada’s Ozempic monograph calls its 0.25 mg start “not a therapeutic dose”, and on Zepbound average loss rose with the dose.2,3
  • Matches the label A few say people with type 2 diabetes tend to lose less. In Wegovy’s monograph, average loss was 9.6% in the diabetes trial, against 14.9% in adults without diabetes.1
  • Not studied Many say semaglutide did little for them but tirzepatide worked after a switch; a few report the reverse. We found no randomized trial of switching after a poor response.
  • Matches the guideline Several say blood sugar, blood pressure or waist size improved while the scale barely moved. Canada’s obesity guideline says health can improve “regardless of the magnitude of weight loss”.5
  • Label says otherwise A few say moving the shot from belly to thigh brought the effect back. Both Canadian monographs say blood levels are similar whether you inject the abdomen, thigh or upper arm.1,2

Advice people share

  • Matches the label Most replies say these medicines work alongside eating less, not instead of it. Canada’s labels approve Wegovy and Zepbound as an adjunct to “a reduced calorie diet and increased physical activity”.1,2
  • Matches the guideline Many say to try the highest dose you can tolerate, with your prescriber, before giving up. The guideline considers adding or switching medicine when goals aren’t met “on the maximum tolerated dose”.5
  • Guideline says otherwise Several suggest routine thyroid and hormone tests for everyone. Canada’s guideline says thyroid tests aren’t routine unless symptoms point to a problem, and lists hormone tests for women with signs of PCOS.6
  • Label says otherwise A few describe extra mid-week shots, dialled partial doses or compounded tirzepatide. Zepbound’s monograph says to inject once weekly and raise the dose only in 2.5 mg steps, and the guideline says compounded medicines “should not be used” for obesity.2,5
RisksThe risks, in brief
  • Stomach effects are common. In Canada’s monographs, 44 in 100 people on Wegovy 2.4 mg felt sick (nausea), against 16 in 100 on placebo. On Zepbound 15 mg it was 28 in 100, against 9 in 100.1,2
  • Gallbladder. Gallstones affected 1.6 in 100 on Wegovy, against 0.7 in 100 on placebo. Zepbound’s monograph links gallbladder events to weight loss.1,2
  • Pancreatitis (an inflamed pancreas) can cause severe stomach pain that won’t go away, sometimes spreading to the back.1
  • Pregnancy. Canada’s obesity guideline doesn’t recommend these medicines in pregnancy, while breastfeeding, or when trying to conceive.5
  • Who shouldn’t take them. Not for anyone with a personal or family history of medullary thyroid cancer or MEN 2.1,2
Full detail in Guide 5: Side effects and risks →
Get help now: call 9-1-1 or go to the nearest emergency department for severe belly pain or pressure, or severe or persistent vomiting.12

Canada’s Wegovy leaflet says to see a healthcare professional straight away for severe, ongoing pain in the stomach area, which could be an inflamed pancreas.1 For advice that isn’t an emergency, most provinces have a nurse line on 8-1-1 (Info-Santé 811 in Quebec).13

Read the full picture

Related questions

Is Mounjaro approved for weight loss in Canada? What is the maintenance dose of Ozempic? What BMI do you need for Wegovy in Canada? Is Zepbound available in Canada?
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Sources

  1. Novo Nordisk Canada. Wegovy (semaglutide injection) Product Monograph, Date of Authorization 2 October 2026 (section 1 indications; 4.2 dose escalation, 2.4 mg from week 17; 10.3 similar exposure in abdomen, thigh or upper arm; 14 STEP 1 and STEP 2, Table 9: at least 5% weight loss in 83.5% vs 31.1% (STEP 1) and 67.4% vs 30.2% (STEP 2), mean change −14.9% and −9.6%; Table 4: nausea 44% vs 16%, cholelithiasis 1.6% vs 0.7%; 7 pancreatitis; contraindications; Patient Medication Information and Instructions for Use). Health Canada Drug Product Database. PDF
  2. Eli Lilly Canada. Zepbound (tirzepatide injection) Product Monograph, Date of Authorization 11 June 2026 (section 1 indications; 4.2 2.5 mg “for treatment initiation”, 2.5 mg steps after at least 4 weeks, maintenance 5, 10 or 15 mg; 4.4 once weekly, 4 doses per pen; 10.3 steady state after 4 weeks, similar exposure in abdomen, thigh or upper arm; 14 SURMOUNT-1 and SURMOUNT-2, Table 7; Table 2: nausea 28.0% on 15 mg vs 8.5%; 7 gallbladder events; contraindications). Health Canada Drug Product Database. PDF
  3. Novo Nordisk Canada. Ozempic (semaglutide injection) Product Monograph, Date of Authorization 13 July 2026 (type 2 diabetes indications; 4.2 “OZEMPIC® 0.25 mg is not a therapeutic dose”). Health Canada Drug Product Database. PDF
  4. Eli Lilly Canada. Mounjaro (tirzepatide injection) Product Monograph, Date of Authorization 23 June 2026 (indicated “to improve glycemic control” in type 2 diabetes). Health Canada Drug Product Database. PDF
  5. Pedersen SD, Manjoo P, Dash S, et al. Canadian Adult Obesity Clinical Practice Guideline: Pharmacotherapy for Obesity Management in Adults, 2025 update. Obesity Canada, Version 3, 11 August 2025 (“considerable heterogeneity in the response”; factors to reassess and adding or substituting medicine “on the maximum tolerated dose”; weight-promoting medicines; traditional 5% at 3 months rule and health gains “regardless of the magnitude of weight loss”; compounded medicines “should not be used”; SURMOUNT-5 summary). PDF
  6. Rueda-Clausen CF, Poddar M, Lear SA, Poirier P, Sharma AM. Canadian Adult Obesity Clinical Practice Guidelines: Assessment of People Living with Obesity. Obesity Canada, Version 1, 4 August 2020 (screening for sleep disorders; hormone tests for women with symptoms of PCOS; other endocrine tests, including thyroid, “not routinely recommended unless clinically warranted”; Table 8: weight-promoting medications). PDF
  7. Wilding JPH, Batterham RL, Calanna S, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med 2021;384:989–1002. doi:10.1056/NEJMoa2032183. PMID 33567185. doi.org
  8. Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med 2022;387:205–216. doi:10.1056/NEJMoa2206038. PMID 35658024. doi.org
  9. Davies M, Færch L, Jeppesen OK, et al. Semaglutide 2.4 mg once a week in adults with overweight or obesity, and type 2 diabetes (STEP 2). Lancet 2021;397:971–984. doi:10.1016/S0140-6736(21)00213-0. PMID 33667417. PubMed
  10. Garvey WT, Frias JP, Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2). Lancet 2023;402:613–626. doi:10.1016/S0140-6736(23)01200-X. PMID 37385275. PubMed
  11. Aronne LJ, Horn DB, le Roux CW, et al. Tirzepatide as compared with semaglutide for the treatment of obesity (SURMOUNT-5). N Engl J Med 2025;393:26–36. doi:10.1056/NEJMoa2416394. PMID 40353578. PubMed
  12. MedlinePlus (US National Library of Medicine). Recognizing medical emergencies (US page: warning signs of a medical emergency from the American College of Emergency Physicians, including severe abdominal pain or pressure and severe or persistent vomiting; call 911 or the local emergency number). Reviewed 8 January 2025. Opened 20 October 2026. medlineplus.gov
  13. Heart and Stroke Foundation of Canada. Medical services by phone (811 health lines by province and territory, including Info-Santé 811 in Quebec). Checked 20 October 2026. heartandstroke.ca

Last checked 20 Oct 2026 · Next review due 20 Oct 2027 · Report an error

How this answer was made. Written by the GLP Guidebook team from the sources above, all checked on 20 Oct 2026. The “in 100” figures for people who didn’t reach 5% are our arithmetic from the monograph tables. The ‘What people report’ section summarizes public patient forum posts we read; it is not medical evidence, and we never pass on advice that goes against the label. It’s general information, not medical advice, and not an advertisement for any medicine. Talk to a doctor, nurse practitioner or pharmacist before starting, stopping or changing any medicine. How we write