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USUnited States Medicines

Why am I not losing weight on Zepbound or Wegovy?

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

Some people lose little, even at full doses. In the main trials, 9 to 15 in 100 people on Zepbound (tirzepatide) and about 14 in 100 on Wegovy (semaglutide) 2.4 mg lost less than 5% of their weight, and more did with type 2 diabetes. NIH advises a check after 12 weeks on the full dose.

Before you go further
  • GLP‑1 medicines are prescription-only in the US. Your prescriber decides your dose and whether to change medicine.
  • Dose facts here come from the US prescribing information (the “label”) for each brand. Trial numbers are group averages, not a promise about you.
  • Nothing here is for sale.

How many people lose little on Zepbound or Wegovy?

In the main trials, 9 to 15 in 100 people on Zepbound and about 14 in 100 on Wegovy 2.4 mg lost under 5%.3,5

These trials left out people with diabetes, and everyone also had diet and activity advice.1,2 On a placebo (dummy injection), 35 in 100 in the Zepbound trial and about 32 in 100 in the Wegovy trial still reached a 5% loss.3,5

Type 2 diabetes changes the numbers. With diabetes, 17 to 21 in 100 on Zepbound and about 31 in 100 on Wegovy 2.4 mg lost less than 5%.4,6 Average loss on Zepbound was 12.8% to 14.7% with diabetes, against 15.0% to 20.9% without.3,4

A 2026 review puts non-response (under 5% lost) at about 10 in 100 in controlled trials of people without diabetes, and higher in routine care. It found that “no single baseline characteristic reliably predicts response.”8

How long before you can tell if it’s working?

NIH says to look for a 5% loss after 12 weeks on the full dose. Before that come weeks or months of lower starting doses.9

Both medicines start low “to reduce the risk of gastrointestinal adverse reactions,” such as nausea.1,2

  • Zepbound: 2.5 mg for 4 weeks, which “is not approved as a maintenance dosage.” It then rises in 2.5 mg steps, each after at least 4 weeks. In the main trials, reaching the assigned dose took up to 20 weeks.1
  • Wegovy injection: 0.25 mg, then 0.5, 1 and 1.7 mg, 4 weeks each. The maintenance dose starts at week 17.2

Each dose takes weeks to build up. Tirzepatide reaches a steady level after 4 weeks, and semaglutide’s half-life (the time for half to leave the body) is about 1 week.1,2

A worked example. On Wegovy 2.4 mg from week 17, the 12-week check falls at week 28 at the earliest. For someone starting at 220 lb (100 kg), 5% is 11 lb (5 kg). Our arithmetic.

Questions to take to your prescriber

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What can a prescriber check or change?

If you lose less than 5% after 12 weeks on the full dose, NIH says your clinician “will probably advise you to stop.” It lists other options too.9

  • Other medicines and conditions: NIH links some medicines to weight gain, including some for depression, epilepsy or psychosis, steroids, insulin and some blood pressure medicines. It also names an underactive thyroid (hypothyroidism), polycystic ovary syndrome (PCOS), Cushing’s syndrome and too little sleep.10
  • A higher dose: Zepbound goes up to 15 mg. Wegovy can go from 2.4 mg to 7.2 mg after at least 4 weeks on 2.4 mg, if more loss is “clinically indicated.” Both labels weigh “treatment response and tolerability.”1,2
  • A different medicine: in SURMOUNT-5, people started on tirzepatide lost 20.2% on average, against 13.7% on semaglutide.7 That trial did not test switching. We found no randomized trial of switching in people who lost little.
  • Diet and activity: the labels pair both medicines with a reduced-calorie diet and more activity. In the Zepbound trials, that meant a deficit of about 500 calories a day and 150 minutes of activity a week.1,2

If you lost weight at first and then stopped, that is a plateau, which our plateau post covers. How prescriptions and coverage work is in Guide 6.

What do people on Zepbound or Wegovy report when the scale won’t move?

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 trial Many say they lost little until a higher dose. In SURMOUNT-1, average loss rose from 15.0% on Zepbound 5 mg to 20.9% on 15 mg.3
  • Matches the trial A few say people with type 2 diabetes lose less. In the trials, about 31 in 100 on Wegovy 2.4 mg with diabetes lost less than 5%, against about 14 in 100 without.5,6
  • Not studied Many say semaglutide did little for them but tirzepatide worked, and a few describe the reverse. We found no randomized trial of switching in people who lost little.
  • Not studied Several describe a slow start, with steady loss coming only months after reaching the full dose.
  • Label says otherwise A few say moving the injection to a new body area brought the effect back. The Zepbound label says exposure was similar in the “abdomen, thigh, or upper arm.”1

Advice people share

  • Matches the label Most replies say to log all food and drink for a few weeks to check intake. Both labels pair the medicine with a reduced-calorie diet.1,2
  • Matches NIH Several suggest asking a clinician about thyroid or hormone problems and reviewing other medicines. NIH links hypothyroidism, PCOS and some medicines to weight gain, and says a clinician may change medicines that might be causing it.9,10
  • Matches the label A few remind new users of pens with screw-on needles, such as Ozempic’s, to take off the inner needle cap. The Ozempic instructions say that if you forget, “you will not inject any medicine.”11
  • Label says otherwise Several threads describe dialing partial doses, adding mid-week doses, or using compounded or “research” products. The labels set fixed doses once a week.1,2 The FDA says compounded drugs “are not FDA approved,” and retatrutide has “not been found safe and effective.”12
RisksThe risks, in brief
  • Stomach effects are common. In the US label trials, nausea hit 25 to 29 in 100 people on Zepbound, against 8 in 100 on placebo, and 44 in 100 on Wegovy 2.4 mg, against 16 in 100 on placebo.1,2
  • Pancreas and gallbladder. Both labels warn of pancreatitis (inflammation of the pancreas) and gallbladder problems.1,2
  • Thyroid warning. Both labels carry a boxed warning about thyroid C-cell tumors seen in rodents.1,2
Full detail in Guide 5: Side effects and risks →
Get help now: call 911 or go to the emergency room for severe stomach pain or pressure, vomiting or diarrhea that won’t stop, or fainting.13

Contact your prescriber right away for stomach pain that will not go away, with or without vomiting, sometimes spreading to your back. The labels list it as a possible sign of pancreatitis.1,2

Read the full picture

Related questions

Can I stay on 2.5 mg of Zepbound if it’s working? Mounjaro vs Zepbound: what’s the difference? Is Ozempic for weight loss or diabetes? Is compounded tirzepatide legal? When should I call 911 on a GLP‑1?
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Sources

  1. Eli Lilly. Zepbound (tirzepatide) US prescribing information (boxed warning, sections 1, 2.1–2.4, 5.4, 5.5, 6.1 Table 1, 12.3, 14) and Medication Guide, revised 08/2026. US label. uspl.lilly.com
  2. Novo Nordisk. Wegovy (semaglutide) injection and tablets, US prescribing information (boxed warning, sections 1, 2.2 Table 1, 5.2, 5.3, 6.1 Table 3, 12.3) and Medication Guide, revised 06/2026. US label. novo-pi.com
  3. 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. Funded by Eli Lilly. doi:10.1056/NEJMoa2206038 · PMID 35658024
  4. 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. Funded by Eli Lilly. doi:10.1016/S0140-6736(23)01200-X · PMID 37385275
  5. 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. Funded by Novo Nordisk. doi:10.1056/NEJMoa2032183 · PMID 33567185
  6. 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. Funded by Novo Nordisk. doi:10.1016/S0140-6736(21)00213-0 · PMID 33667417
  7. 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. Funded by Eli Lilly. doi:10.1056/NEJMoa2416394 · PMID 40353578
  8. Kuryłowicz A, Czupryniak L. Responders vs. non-responders or how to predict the response to GLP-1 or GLP-1/GIP receptor agonist therapy. Narrative review. Diabetes Obes Metab 2026, online Aug 23. doi:10.1111/dom.71226 · PMID 42634284
  9. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK, part of NIH). Prescription medications to treat overweight and obesity. Last reviewed June 2024. niddk.nih.gov
  10. NIDDK (NIH). Factors affecting weight and health. Last reviewed May 2023. niddk.nih.gov
  11. Novo Nordisk. Ozempic (semaglutide) US prescribing information, revised 05/2026, Instructions for Use, step 1. US label. novo-pi.com
  12. US Food and Drug Administration. FDA’s concerns with unapproved GLP-1 drugs used for weight loss. Content current as of Oct 1, 2026. fda.gov
  13. MedlinePlus (US National Library of Medicine). Recognizing medical emergencies (warning signs from the American College of Emergency Physicians). Review date 1/8/2025. medlineplus.gov

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

How this answer was made. Written by the GLP Guidebook team from the sources above, all checked on Oct 20, 2026. 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. Talk to a doctor, pharmacist or other licensed prescriber before starting, stopping or changing any medicine. In an emergency, call 911. How we write