UK weight loss medicine prices
On average, yes, by a small margin. In SURMOUNT-5, which compared Mounjaro with Wegovy, weight loss was about 6% greater in women than in men on both medicines. A 2025 review of 14 studies of similar medicines found women lost about 1 kg more than men. The reasons are not settled, and your own result depends on far more than your sex.
Women made up most of each trial
For much of the last century, drug research treated the male body as the default. The weight loss medicine trials turned that around. Women were the majority in every one of the main trials below, so the average results already describe women well. This is evidence catching up, not women against men. Our guide to women in medical research covers the wider gap.
| Trial | Medicine | People | Share who were women |
|---|---|---|---|
| STEP 1 (2021) | Wegovy | 1,961 | 74.1% |
| SURMOUNT-1 (2022) | Mounjaro | 2,539 | 67.5% |
| SURMOUNT-5 (2025) | Mounjaro and Wegovy | 751 | 64.7% |
What the comparisons by sex show
Three published papers compare women and men directly. They point the same way, with different strengths of evidence.
| Study | Medicines | What it found |
|---|---|---|
| SURMOUNT-5, NEJM 2025 | Mounjaro and Wegovy | Weight loss about 6% greater in women than men on both |
| Yang et al, Journal of Diabetes 2025 | Five GLP-1 medicines including semaglutide, not tirzepatide | Women lost 1.04 kg more, or 1.69 percentage points more |
| Look et al, Diabetes, Obesity and Metabolism 2025 | Mounjaro (SURMOUNT-1 body scan group) | No significant difference between women and men in the effect on weight |
SURMOUNT-5 gives the most direct answer for Mounjaro. The authors also note their trial had more men, 35%, than earlier trials, which matters when you compare its average results with older ones.
The 2025 review by Yang and colleagues pooled 14 studies of dulaglutide, exenatide, liraglutide, semaglutide and retatrutide. Women lost more weight than men overall. For semaglutide alone, the gap was 1.04 kg. Exenatide showed no gap. The bigger the overall weight loss, the bigger the gap between the sexes tended to be.
The SURMOUNT-1 body composition study scanned a smaller group and found no significant difference by sex. The authors say the group was small and the comparison was done after the trial ended, so they advise against reading much into differences between subgroups.
Why the gap might exist
None of these papers proves a cause. The Yang review tested several possible explanations, and dose, length of treatment, starting weight and background treatment did not account for the difference. The SURMOUNT-1 body composition paper offers no explanation. Theories you may read elsewhere, such as women getting more medicine per kilo of body weight, are not tested in the papers cited here.
Fat or muscle: what women lose
The same SURMOUNT-1 scans measured what kind of weight went. On Mounjaro, 75% of the weight women lost was fat, against 73% for men. The rest was lean tissue, which includes muscle, water and organ weight. The split was close to the split on placebo, so the medicine did not take an unusual share of muscle. Protein and strength exercise still help you keep what you have. Our keeping muscle guide shows how.
Menopause stage made little difference
A 2025 analysis in the journal Obesity looked only at women in SURMOUNT-1 on the 15mg or highest tolerated dose, grouped by menopause stage. Women before the menopause lost 26% of their weight. Women in the perimenopause and after the menopause lost 23%. Women on placebo lost 2% to 3%. In every group, 97% to 98% of women on Mounjaro lost at least 5% of their weight.
| Stage | Weight lost on Mounjaro | Weight lost on placebo | Waist reduction on Mounjaro |
|---|---|---|---|
| Before the menopause | 26% | 2% | 22 cm |
| Perimenopause | 23% | 3% | 20 cm |
| After the menopause | 23% | 3% | 20 cm |
If you are in your 40s or 50s, these figures are good news. Our perimenopause guide and menopause weight gain guide cover what to protect while the weight comes off.
What this means for you
- The trial averages already describe women, because women were the majority in each one.
- The average gap in the Yang review was about 1 kg. Your own result depends on more than your sex.
- Our first month guide sets out what the trials show for month 1.
- If you take the contraceptive pill, the NHS advises extra barrier contraception for 4 weeks after starting Mounjaro and after each dose increase.
- For the full picture on benefits and NHS access, start with our Mounjaro for women guide.
If you are weighing Mounjaro against Wegovy, our best injection for women guide sets out the SURMOUNT-5 results in full. Current prices for every Mounjaro dose are on our Mounjaro price page.
Paying for your own medicine? The lowest first-order prices today, with delivery included: Mounjaro from £89.00, Wegovy from £44.00, Wegovy pill from £52.99, Foundayo from £49.00.
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- Tirzepatide as compared with semaglutide for the treatment of obesity (SURMOUNT-5) (Aronne et al, New England Journal of Medicine, 2025 (author manuscript, Weill Cornell eCommons))
- Sex differences in the efficacy of GLP-1 receptor agonists for weight reduction: a systematic review and meta-analysis (Yang et al, Journal of Diabetes, 2025)
- Body composition changes during weight reduction with tirzepatide in the SURMOUNT-1 study (Look et al, Diabetes, Obesity and Metabolism, 2025)
- Body weight reduction in women treated with tirzepatide by reproductive stage (Tchang et al, Obesity, 2025)
- Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1) trial summary (American College of Cardiology)
- Once-weekly semaglutide in adults with overweight or obesity (STEP 1) (Wilding et al, New England Journal of Medicine, 2021 (open access copy, University of Leicester))
- Tirzepatide (NHS)