Newer obesity medications can lead to substantial weight loss, but a large review suggests the broader health picture is more complicated than pounds lost alone.
The systematic review and network meta-analysis, published in The BMJ, included 262 randomized controlled trials involving nearly 100,000 adults with overweight or obesity. Researchers compared 19 current and emerging obesity medications and found that several produced meaningful weight loss after one year. But the review also found that greater weight loss often came with more side effects, more treatment discontinuation and limited evidence that most drugs meaningfully improved quality of life or longer-term heart and kidney outcomes. The findings do not mean obesity medications are ineffective or that people should avoid them. They suggest treatment decisions should look beyond average weight loss and consider benefits, harms, cost, access and patient preferences.
The review found the largest estimated weight loss after one year with tirzepatide, at 14.9%, and CagriSema, at 14.8%. Oral semaglutide was linked with 10.9% weight loss, followed by orforglipron at 9.9%, subcutaneous semaglutide at 9.8% and phentermine-topiramate at 8.1%.
Emerging drugs, including retatrutide, ecnoglutide and mazdutide, also showed large effects on weight loss, but the researchers rated the certainty of evidence for those medications as low or very low. That matters because early trial results can look promising before longer, larger or more diverse studies are available.
The review also found a trade-off. Greater weight loss was generally accompanied by more harms, including gastrointestinal symptoms, fatigue and treatment discontinuation. Some medications were also linked with loss of lean mass, a category that includes muscle but also water, organs and other nonfat tissue.
Tirzepatide was linked with the greatest reduction in fat mass, at 25.7%, but also the greatest reduction in lean mass, at 8.3%. That does not mean people taking tirzepatide are simply “losing muscle,” but it does point to an important question for obesity care: How can treatment support fat loss while preserving strength, function and overall health?
The cardiovascular findings were also mixed. Subcutaneous semaglutide was the only drug in the review associated with a reduced risk of death from any cause, heart attack and heart failure. Tirzepatide was also associated with a lower risk of heart failure. But for most drugs, the review did not find convincing evidence of cardiovascular benefit at one year.
That does not prove those benefits do not exist. Many trials were relatively short, and heart and kidney outcomes often require longer follow-up. It means the current evidence is still uneven, especially for newer medications and outcomes beyond weight loss.
The review also found no drug convincingly reduced kidney failure or showed clinically important improvements in quality of life. That may surprise readers who associate major weight loss with feeling better. But quality of life can be shaped by many factors, including side effects, medication burden, cost, access, stigma, body composition, energy levels and whether weight regain occurs after treatment stops.
The authors concluded that obesity treatment should be individualized, “balancing expected benefits, harms, treatment burden, costs, availability, and patient preferences.”
That point is especially important in a fast-moving treatment landscape. Medications such as semaglutide and tirzepatide have changed the conversation around obesity care, and newer drugs are already being studied. But “more weight loss” is not the only outcome that matters to patients or clinicians.
The review has limits. It used a network meta-analysis, which allows researchers to compare treatments across many trials even when direct head-to-head studies are limited. That approach is useful, but it depends on assumptions across different study designs, participants, doses and follow-up periods. The authors also noted that many trials had relatively short follow-up, limiting conclusions about long-term safety, quality of life and heart and kidney outcomes.
Still, the review offers a useful reminder: Obesity medications are not interchangeable, and the best choice is not always the drug with the largest average weight-loss number. For some patients, the priority may be cardiovascular risk. For others, it may be tolerability, preserving strength, affordability, access or whether a treatment can be sustained.
The study was supported by the Noncommunicable Chronic Diseases-National Science and Technology Major Project, Chengdu Science and Technology Bureau Key R&D Support Plan, National Natural Science Foundation of China and the 1.3.5 project for disciplines of excellence at West China Hospital, Sichuan University.
Several authors disclosed professional or financial ties relevant to obesity, diabetes or pharmaceutical research. These included consulting, speaker roles, research grants, travel support, clinical obesity care ownership or other relationships involving companies such as Novo Nordisk, Eli Lilly, Johnson & Johnson, Boehringer Ingelheim, AstraZeneca, Sanofi, Pfizer, Roche, Nestle Health Science and others. The authors noted that two authors with relevant industry or clinical ties did not assess risk of bias or extract data for the review.