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Why am I not losing weight on Mounjaro or Wegovy?

GLP Guidebook teamUpdated 20 Oct 202611 sourcesWritten from published sources
What we checked11 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

The clearest reasons on the Australian labels for slow loss on Mounjaro (tirzepatide) or Wegovy (semaglutide) are being on a starting dose and having type 2 diabetes. Some people also respond less. In the main trials, 4 to 11 in 100 on Mounjaro and about 1 in 6 on Wegovy lost under 5% of their weight.

Before you go further
  • Mounjaro and Wegovy are prescription-only medicines in Australia. Your prescriber decides your dose and whether to carry on.
  • The facts come from each Australian Product Information (PI) for prescribers and the Consumer Medicine Information (CMI) leaflet.
  • We don’t publish medicine prices for Australia.

How many people lose little or no weight?

In the main Australian-label trials, 4 to 11 in 100 people on Mounjaro and about 1 in 6 on Wegovy lost under 5%.1,3

In SURMOUNT-1, 2,539 adults without diabetes had Mounjaro or a dummy injection (placebo) for 72 weeks. Depending on the dose, 89 to 96 in 100 on Mounjaro lost at least 5%, against 28 in 100 on the dummy.1

STEP 1 ran for 68 weeks. 84 in 100 adults on Wegovy 2.4 mg lost at least 5%, against 31 in 100 on the dummy.3 For a 100 kg person, 5% is 5 kg.

Could the dose be the reason?

It can be. Both medicines start low and step up over months, and most early steps aren’t meant as doses to stay on.1,3

  • Mounjaro starts at 2.5 mg, then 5 mg, rising in 2.5 mg steps at least 4 weeks apart, to 15 mg at most. The label says 2.5, 7.5 and 12.5 mg are not maintenance doses.1 In SURMOUNT-1, average loss was 16.0% on 5 mg and 22.5% on 15 mg.1
  • Wegovy rises from 0.25 mg over 16 weeks to 2.4 mg, to reduce stomach side effects. If 2.4 mg isn’t tolerated, the label allows 1.7 mg as the maintenance dose. Adults who started with a BMI of 30 or more can later move to 7.2 mg, and go back to 2.4 mg if weight doesn’t improve further.3
  • Ozempic is also semaglutide, but in Australia it is registered for type 2 diabetes, at doses up to 2 mg.4

What else can slow weight loss?

Type 2 diabetes is the clearest factor in the trials. People with diabetes lost less on both medicines than people without it.1,3

In SURMOUNT-2, adults with type 2 diabetes lost 13.4% to 15.7% on Mounjaro, against 3.3% on the dummy.1 In STEP 2, adults with diabetes lost 9.6% on Wegovy, against 3.4%.3

healthdirect lists things that affect weight, including medical conditions, certain prescription medicines, short sleep, stress and alcohol.6 An underactive thyroid can cause weight gain,7 and polycystic ovarian syndrome (PCOS) can make weight hard to lose.8 These pages cover weight in general.

Injection site seems not to matter: both labels report similar blood levels from tummy, thigh or upper arm.1,3 The Mounjaro leaflet warns you can underdose if the KwikPen knob isn’t turned to the ‘1’ icon.2

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What happens if it still isn’t working?

Your prescriber reviews the plan. The Australian Obesity Management Algorithm, from the Australian Diabetes Society, says treatment is stepped up over time if weight and health targets aren’t met.5

We found no adult stopping rule based on weight in either label. Wegovy’s rule for teenagers is to stop if BMI hasn’t fallen 5% after 12 weeks on 2.4 mg or the highest dose they tolerate.3 The Mounjaro label says blood levels settle after 4 weeks on a dose, and each step up comes at least 4 weeks after the last.1

The algorithm says smaller losses still help: about 5% lowers diabetes risk. If a very low energy diet plus medicine doesn’t work, it lists surgery as an option.5

In SURMOUNT-5, adults lost 21.6% on tirzepatide and 15.4% on semaglutide over 72 weeks. It didn’t test switching after a poor response.1 If weight fell and then stopped, that’s a plateau.

What do people on Mounjaro and Wegovy report about slow or no weight loss?

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 felt little on the first doses and only noticed a change higher up. The Australian labels list those first doses as steps on the way up, not maintenance doses.1,3
  • Matches the trials A few with type 2 diabetes say they lost less than others. SURMOUNT-2 and STEP 2 found the same.1,3
  • Not studied Many say semaglutide did little for them but tirzepatide worked; a few describe the reverse. SURMOUNT-5 compared the two but didn’t test switching after a poor response.1
  • Label says otherwise A few say changing injection site brought the effect back. Both Australian labels report similar blood levels from the tummy, thigh or upper arm.1,3

Advice people share

  • Matches the labels Most replies say eating less is still part of it. Both labels list the medicine as an add-on to a lower-energy diet and more activity.1,3
  • Matches healthdirect Several say to ask a GP about thyroid and hormone problems; a few also mention other medicines. healthdirect lists medical conditions and certain prescription medicines among things that affect weight.6,7
  • Matches the leaflet A few say a pen mistake can mean injecting too little. The Mounjaro leaflet also warns about underdosing, and says to turn the dose knob until it stops at the ‘1’ icon.2
  • Label says otherwise Several posts describe counting pen clicks for in-between doses, splitting doses or adding extra ones. The Australian label sets one Mounjaro dose a week, rising in 2.5 mg steps at least 4 weeks apart, to 15 mg at most. The leaflet says each pen holds 4 doses, one a week.1,2
RisksThe risks, in brief
  • Nausea is very common. In the Mounjaro weight trials it affected 24.6 to 29.0 in 100 people on 5 mg to 15 mg, against 8.5 in 100 on a dummy injection.1
  • On Wegovy, nausea affected 43.9 in 100 over 68 weeks, against 16.1 in 100 on a dummy injection, mostly while the dose was going up.3
  • Gallstones and pancreatitis (an inflamed pancreas) are listed as uncommon (1 in 1,000 to 1 in 100) on the Australian Mounjaro label.1 Gallstones were reported in 16 in 1,000 people on Wegovy, against 11 in 1,000 on a dummy injection.3
Full detail in Guide 5: Side effects and risks →
Get help now: call triple zero (000) and ask for an ambulance if you have signs of a severe allergic reaction:
  • difficult or noisy breathing10
  • a swollen tongue, or swelling or tightness in the throat10
  • persistent dizziness or collapse10
For severe pain in your tummy, go straight to the nearest emergency department or call 000.9 Call 000 for any illness that feels critical or life-threatening.11

Call your doctor straight away, or go to the emergency department, if you have any of these, the Mounjaro leaflet says:2

  • severe stomach and back pain that won’t go away
  • sudden severe upper-stomach pain with fever, or yellow skin or eyes
  • changes to your vision

For advice any time, call healthdirect on 1800 022 222.11

Read the full picture

Related questions

What is the maintenance dose of Mounjaro or Wegovy? Do you have to take Mounjaro or Wegovy for life? Can I get Ozempic for weight loss in Australia? What BMI do I need for Wegovy or Mounjaro in Australia? When should I call 000 on a GLP‑1?
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Sources

  1. Eli Lilly. Mounjaro and Mounjaro KwikPen (tirzepatide) Australian Product Information, vA14.0, October 2026, sections 4.1, 4.2, 4.8, 5.1 (SURMOUNT-1, SURMOUNT-2 and SURMOUNT-5) and 5.2. Australian label. medsinfo.com.au (PDF)
  2. Eli Lilly. Mounjaro KwikPen (tirzepatide) Consumer Medicine Information, prepared September 2026, sections 4 and 6. Australian leaflet. medsinfo.com.au (PDF)
  3. Novo Nordisk. Wegovy (semaglutide) Australian Product Information, date of revision 22 June 2026, sections 4.1, 4.2, 4.8, 5.1 (STEP 1 and STEP 2) and 5.2. Australian label. medsinfo.com.au
  4. Novo Nordisk. Ozempic (semaglutide) Australian Product Information, date of revision 25 September 2026, sections 4.1 and 4.2. Australian label. medsinfo.com.au (PDF)
  5. Markovic TP et al., Australian Diabetes Society. The Australian Obesity Management Algorithm, July 2024. diabetessociety.com.au (PDF)
  6. healthdirect. Obesity (last reviewed September 2024), “What causes obesity?”. healthdirect.gov.au
  7. healthdirect. Hypothyroidism (last reviewed October 2024). healthdirect.gov.au
  8. healthdirect. Polycystic ovarian syndrome (PCOS) (last reviewed December 2024). healthdirect.gov.au
  9. healthdirect. Abdominal pain (last reviewed February 2024). healthdirect.gov.au
  10. healthdirect. Anaphylaxis (last reviewed November 2024). healthdirect.gov.au
  11. Healthdirect Australia. How healthdirect can help you (“call triple zero (000) for an ambulance immediately”; nurse helpline 1800 022 222). healthdirect.gov.au

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 ‘What people report’ section summarises public patient forum posts we read; it is not medical evidence, and we never pass on advice that goes against the label. We don’t publish medicine prices, and we don’t name, rank or link to sellers or telehealth services. It’s general information, not medical advice, and nothing here is an offer to supply any medicine. Talk to a GP, pharmacist or other qualified prescriber before starting, stopping or changing any medicine. How we write