Do Women Lose More Weight on Retatrutide Than Men? The Short Answer

In the Phase 3 TRIUMPH-1 trial, women lost a larger share of their body weight than men at every retatrutide dose. On the highest dose, 12 mg, women lost 26.3% of their body weight over 80 weeks and men 22.3%, counting everyone randomized whether or not they stayed on treatment. If the drug was taken as intended, the figures were 30.8% for women and 23.2% for men.

Two points put the gap in context:

• Women started lighter. Average starting weight was 104.9 kg for women and 127.7 kg for men, so the same percentage means fewer kilograms for women. Applied to those averages, 26.3% and 22.3% come to roughly 28 kg in both groups (our rough calculation; the appendix does not report kilograms by sex).
• The paper reports no test of the difference. It says weight reduction "appeared to be greater among women than among men" and that its prespecified analyses "suggested greater weight loss in women than in men." It does not report a statistical test of the difference or explain it.

The results come from the paper published in the New England Journal of Medicine in September 2026 and its supplementary appendix. The overall results are covered in TRIUMPH-1 results.

Retatrutide Weight Loss in Women and Men by Dose

TRIUMPH-1 randomized 2,339 adults with obesity, or overweight with a weight-related condition, and without diabetes to retatrutide 4 mg, 9 mg or 12 mg or placebo for 80 weeks. The supplementary appendix shows weight change separately for women and men with two estimands, two ways of counting people who stopped treatment or started other weight-loss treatments, explained in why retatrutide weight loss numbers differ.

Weight change at 80 weeks (TRIUMPH-1):

"Everyone randomized" is the treatment-regimen estimand, which counts every participant whether or not they stayed on treatment. "As intended" is the efficacy estimand, which estimates the result had everyone taken their assigned treatment, retatrutide or placebo, for the full 80 weeks without starting other weight-loss treatments. All figures are model-based estimates shown in Figure S6 of the appendix.

Three patterns stand out in these figures:

• The gap held at every dose. Counting everyone randomized, women lost about 4 to 6 percentage points more than men on each retatrutide dose.
• Placebo went the other way. Men on placebo lost slightly more than women on placebo (4.9% against 3.4%). Subtracting placebo, the 12 mg result was about 23 points for women and 17 points for men counting everyone randomized, and about 29 and 20 points as intended (our calculation).
• Dose response looked different. In women, 9 mg and 12 mg gave almost the same result counting everyone randomized (25.9% and 26.3%). In men, 12 mg was further ahead of 9 mg (22.3% and 19.6%). The paper does not comment on this.

For comparison, the whole trial population lost 25.0% on 12 mg counting everyone randomized and 28.3% as intended. How weight loss built up over the 80 weeks is covered in retatrutide weight loss timeline.

Percent vs Kilograms: Why the Gap Shrinks in Kilograms

Weight loss in obesity trials is reported as a percentage of starting weight. Because women in TRIUMPH-1 started about 23 kg lighter than men on average, a higher percentage for women does not necessarily mean more kilograms lost.

Retatrutide 12 mg, 80 weeks:

The kilogram figures are our rough calculation: each percentage applied to the mean starting weight shown in Figure S6 of the appendix, one value per sex for all treatment groups combined, not to the 12 mg group alone. They show the size of the effect of starting weight, not exact results. On this rough basis, the two sexes lost a similar number of kilograms counting everyone randomized, and women lost slightly more when the drug was taken as intended.

The paper does not explain why women lost a larger share of their weight. It gives no breakdown by menopause status or other factors that differ between women and men.

Who Took Part: About Two Thirds Were Women

Of the 2,339 participants, 1,533 (65.5%) were women, with almost identical shares in each group (our sum of the figures in Table 1 of the paper). According to the appendix, enrollment of women was capped at 70% in each country "to ensure a sufficient number of male participants," and, according to the paper, randomization was stratified by sex so that each group had a similar mix. Sex was reported by the participants.

The share of women differed between the trial's two specialized groups:

• Knee osteoarthritis group: 75.8% women (435 of 574). Results for this group are in retatrutide for knee osteoarthritis.
• Sleep apnea group: 36.6% women (89 of 243). Results are in retatrutide for sleep apnea.
• Extension to 104 weeks: 63.2% women (336 of 532).

The appendix's table on how representative the trial was notes that knee osteoarthritis is more common in women, with about 60% of cases worldwide in women, and that sleep apnea is approximately twice as common in men.

Women who were pregnant, planned to become pregnant or were breastfeeding could not take part, so the trial was not designed to assess retatrutide in pregnancy or breastfeeding. The appendix lists a few participants who stopped treatment because of pregnancy, without reporting outcomes.

Side Effects in Women and Men

The one side effect the TRIUMPH-1 paper reports by sex is urinary tract infection. Urinary tract infections were reported in 7.5% to 8.7% of participants on retatrutide and 5.3% on placebo, and 92% of these events occurred in women, who made up about two thirds of the participants. The authors wrote that they occurred "almost exclusively in women." The details are in retatrutide and urinary tract infections.

We found no other side effects reported separately for women and men in the paper or its appendix, including nausea, dysesthesia and low blood pressure; the appendix lists only the age and sex of each of the six participants who died. The full list for all participants is in retatrutide side effects.

What Is Still Unknown

• Why women lost a larger percentage. The paper reports the difference but gives no explanation and no statistical test of it.
• Results by sex in the other trials. We have not found weight results by sex in the published results of the other Phase 3 trials.
• Side effects by sex, apart from urinary tract infections.
• Pregnancy and breastfeeding, which were excluded from the trial.

Retatrutide Sold Online: Why the Trial Data Don't Apply

Retatrutide is not approved and, according to its developer, is legally available only through clinical trials; its regulatory position is tracked in retatrutide approval status. The company says anything sold to consumers outside those trials is illegal, and warns that illicit retatrutide products may contain "unknown ingredients, harmful contaminants and impurities." The results above come from a controlled trial in which participants received the study drug under medical supervision.

Sources

• Jastreboff AM, Kaplan LM, Davies MJ, et al. Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity. N Engl J Med. Published September 29, 2026; updated October 22, 2026. DOI: 10.1056/NEJMoa2604169. Supplementary Appendix: Figure S6, Tables S4 and S5, inclusion criteria. (TRIUMPH-1)
• Eli Lilly. What to know about retatrutide. Last updated September 2026.

Medical Disclaimer: This article is for informational purposes only and is not medical advice. Retatrutide is investigational and is not approved by the FDA for any use. It is not available by prescription, and Lilly says anything sold to consumers under its name outside its clinical trials is illegal. The figures described here are those reported in clinical trials under medical supervision.