Conference Coverage

‘Staggering’ weight loss and benefits in body composition with tirzepatide


Substantial reductions in body weight across body mass index categories, as well as improved body composition, were achieved with tirzepatide (Mounjaro) in adults for chronic weight management, according to the latest results of the SURMOUNT-1 study.

The new analysis showed that up to 63% of participants achieved a reduction in body weight of at least 20%, and all three tirzepatide doses (5 mg, 10 mg, and 15 mg) led to substantial, clinically meaningful, and sustained body-weight reduction, compared with placebo at 72 weeks of follow-up.

Mean weight loss was –16.0%, –21.4%, and –22.5% with tirzepatide 5 mg, 10 mg, and 15 mg, compared with –2.4% for placebo (all P < .001 vs. placebo). And among participants taking the highest 15-mg dose of tirzepatide, 96%, 90%, and 78% of patients achieved weight reductions of at least 5%, 10%, and 15%.

Tirzepatide is approved in the United States and the European Union for the treatment of type 2 diabetes but is not yet approved for obesity in any country. The manufacturer of tirzepatide, Eli Lilly, intends to seek approval for the drug as an obesity treatment from the U.S. Food and Drug Administration, European Medicines Agency, and in other territories beginning in 2023.

Regardless of baseline BMI category, 9 out of 10 people achieved the greater than or equal to 5% body weight reduction threshold across all doses of tirzepatide, and at the higher doses, over one-third achieved weight loss of 25% or more.

“Similar to lifestyle and surgical treatments, participants on tirzepatide had around a threefold greater percent reduction in fat mass, compared with lean mass, resulting in an overall improvement in body composition,” reported SURMOUNT-1 co-investigator Louis Aronne, MD, Comprehensive Weight Control Center, Weill Cornell Medicine, New York.

Dr. Louis J. Aronne, Weill Cornell Medicine, New York

Dr. Louis J. Aronne

“This is staggering weight loss,” remarked Dr. Aronne. “To put it in perspective, mean weight loss in people having Lap-Band surgery is 17%, mean weight loss for sleeve gastrectomy is 25%, and gastric bypass is 33%, which puts the effects of tirzepatide squarely in the realm of bariatric surgery.”

“Something we have sought for decades, we have finally been able to achieve,” he asserted. “I still remember exactly where I was when I saw these results for the first time last April. I knew something big was happening,” declared Dr. Aronne when presenting the latest analyses at the 2023 European Congress on Obesity. Full study results were published in the New England Journal of Medicine.

Moderator Gabriella Lieberman, MD, endocrinologist and head of the Israeli Center for Weight Management, Sheba Medical Center, Ramat-Gan, Israel, welcomed the study but also expressed caution. “It’s very potent, but as we see generally with potent therapies, I think it will change how we look at nutritional advice and the role of the dietician will change. I’m a bit worried the drug is running fast and the support, which is crucial with these treatments, is not keeping up, and we’ll have to deal with some effects later, such as sarcopenia,” she pointed out in an interview.

“We have to treat these drugs as if they are bariatric surgery. I see patients on these types of drugs in clinic and their appetite is so suppressed that they think they can afford to eat things that are unhealthy because they lose weight, and that’s what they want. There has to be a responsible adult looking at what they’re eating, and not just clapping their hands for the weight loss, but ensuring they are not deprived of anything,” she said.


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