Obesity drugs bring weight loss but not better quality of life, study finds

Published in The BMJ, the study analysed 262 clinical trials involving around 100,000 participants and 19 different drugs. The researchers found that greater weight loss was consistently associated with higher rates of adverse events and treatment discontinuation. “Most agents do not improve quality of life meaningfully and few show cardiovascular benefits,” the authors of the study wrote In the trials, participants completed standard health‑related quality‑of‑life questionnaires. Researchers compared how much these scores changed with the weight‑loss drugs versus lifestyle changes alone and found that across the main treatments there were no clinically meaningful improvements in quality of life. Out of all the treatments studied in the clinical trials, tirzepatide — the active ingredient in Mounjaro and Zepbound — and CagriSema — which is not currently approved for clinical use — provided the greatest reductions in body weight among drugs for overweight adults. Subcutaneous semaglutide — used in Ozempic and Wegovy — currently has the strongest evidence for reductions in mortality and major cardiovascular events, the study found. However, both tirzepatide and semaglutide were also linked to a harmful reduction in lean mass, the total weight of the body minus fat mass. Low lean mass has been associated with a higher risk of falls, bone fractures, and early death. The study's authors noted that most of the trials analysed had short follow-up periods and that more research is needed into newer drugs to fully understand their long-term impact. Researchers not involved in the study warn, however, that findings on quality of life require particularly careful interpretation, as the way it is measured can vary widely. “Quality of life is complex and varies between individuals. While standardised measures provide valuable information, they may not capture all aspects of treatment experience that matter to people living with obesity,” noted Marie Spreckley at the University of Cambridge.

Treating obesity is more than losing weight

Obesity is increasingly recognised as a complex chronic disease, and relying on weight loss alone as a measure of treatment success may oversimplify its benefits and harms while reinforcing stigma around the condition, the authors warned. “The study fits with what we already knew: some medications lead to substantial weight loss, but losing weight does not automatically mean improving every aspect of health,” said José M. Ordovás at Tufts University, who did not participate in the study. “The scale tells part of the story, but not all of it,” he noted, adding that in obesity, success should not be measured only in kilos but in health, function, and quality of life.