Women lost a higher percentage of their body weight than men when taking tirzepatide, prescribed as Zepbound for weight loss and Mounjaro to treat type 2 diabetes, a new analysis found.
After combining the results of four tirzepatide studies, investigators found that although both men and women consistently lost weight while on the drug, women lost up to 25 percent of their starting body weight on average, compared with 18 percent for men.
The research was presented at this year’s annual meeting of the European Association for the Study of Diabetes (EASD), held in Madrid September 9–13.
Women Lost More Weight on Tirzepatide Than Men
Tirzepatide is a once-weekly injectable medication that targets two key hormones involved in appetite and glucose regulation: glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). Semaglutide, prescribed as Ozempic for type 2 diabetes and Wegovy for weight loss, only mimics GLP-1.
These drugs work by regulating the body’s blood sugar levels, slowing down digestion, and reducing appetite, which makes a person feel fuller, eat less, and lose weight.
To explore how men and women might respond differently to tirzepatide, researchers analyzed findings from studies with more than 4,500 people who were overweight or had obesity, with or without diabetes.
Scientists looked at the average percentage change in body weight at one year and 72 weeks.
On average, women lost up to 24.6 percent of their body weight with tirzepatide, compared with 18.1 percent for men.
Women consistently lost more weight than men in all four trials compared with the group taking the placebo. For women, the weight reduction ranged from 11.5 percent to 27.6 percent, while for men it ranged from 8.8 percent to 18.9 percent.
In addition, similar percentages of males and females achieved at least a 5 percent, 10 percent, or 15 percent weight reduction in three of the four trials. But in the SURMOUNT 3 trial involving adults without type 2 diabetes, tirzepatide-treated females were significantly more likely to achieve a body weight reduction of at least 5 percent and 10 percent than tirzepatide-treated males.
The results of the analysis have to be interpreted with caution because the study is “hypothesis-generating” only, says the lead author, Luis-Emilio García-Pérez, MD, PhD, an associate vice president in the diabetes global medical affairs team of Eli Lilly and Company, the manufacturer of tirzepatide.
That means that the study was designed to see if there was any type of pattern in men versus women, but it doesn’t prove that these differences are meaningful, or that sex differences caused the disparity in the amount of weight lost.
The prevalence of obesity and how each sex responds to treatment are influenced by many factors, and further research is needed to understand the findings, says Dr. García-Pérez.
The idea that women might lose a higher percentage of their body weight on tirzepatide is intriguing, but it’s too early to draw any conclusions from this analysis, says Dan Azagury, MD, a weight loss physician and bariatric surgeon at Stanford Medicine in Palo Alto, California.
Only an abstract of the study has been released (it hasn’t yet been published in a peer-reviewed journal) and there are too many factors that could influence the findings to definitely say that the differences are due to sex, says Dr. Azagury, who wasn’t involved in the study.
Previous Research Also Found Women Lost More Weight on a GLP-1
Women Reported More Nausea and Vomiting
Women reported more nausea and vomiting on tirzepatide than men. The percentage of women experiencing nausea was close to double that of men in all four trials, and in three out of four trials, the percentage of women with vomiting was also twice as high.
The finding that women reported more side effects is interesting, and should be explored further, says Azagury.
“The side effects of these medications are usually transient and go away or improve within a few weeks,” he says.
That means it’s unlikely that the vomiting or nausea actually caused the weight loss — but it could potentially be an indication that the medication had a stronger effect in women, he says.
“But if you look at the starting weights, on average men weighed 20 or 30 kilograms more than the women, but the dosing is the same for men and women,” says Azagury.
So it could be that the drug had a stronger effect (which could also cause more side effects) in women not because of their sex, but because of their size — but that needs to be looked at more closely, he says.
