CATEGORY: DIET & WEIGHT
Pounds lost turns out to be a poor way to rank weight-loss drugs. Researchers who pooled 262 randomized trials covering 99,791 adults with overweight or obesity found that only one of 19 medications, injected semaglutide, was tied to fewer deaths, a 19% lower risk, along with 28% fewer heart attacks and 57% less heart failure.1 Tirzepatide, the strongest drug on the scale, trimmed heart failure risk by about half but moved none of the other health outcomes.
Ranking Every Drug Against Every Other
A team at West China Hospital, working with international evidence specialists, gathered every randomized trial of an obesity medication they could find through late 2025 and linked them into a single statistical network, so drugs never tested head to head could still be compared. Follow-up ran from twelve weeks to more than three years. For weight itself, the hierarchy was clear. Tirzepatide led, taking off 14.9% of body weight in a year. The newer combination CagriSema matched it at 14.8%. Oral semaglutide, orforglipron and the semaglutide injection clustered near 10%. Older drugs like phentermine-topiramate sat lower still. Several just-emerging drugs posted big numbers on thin, low-certainty evidence.
Where the Weight Loss Didn’t Carry Over
Then the picture flips. Across 43 trials that measured quality of life, no drug improved it convincingly, by an amount people would actually notice. No drug convincingly protected the kidneys. And the survival and heart benefits concentrated in a single medication, largely on the strength of long trials run in people who already had heart disease or high risk, so the review can’t say the same applies to otherwise healthy adults. The semaglutide numbers echo what its landmark heart-outcomes trial reported, now set against 18 rival drugs that have shown nothing comparable, mostly because they haven’t been tested that long.
Why One Drug Stands Alone, for Now
The gap says as much about testing as about chemistry. Proving a drug prevents heart attacks or extends life takes years of follow-up in tens of thousands of people. Injected semaglutide is the only obesity drug that has finished trials of that size and length. Its rivals mostly have a year or two of weight data. So the ranking could shift. Large outcome trials of the newer drugs are underway, and their results will redraw this comparison. The emerging drugs posting the flashiest weight numbers, retatrutide, ecnoglutide and mazdutide, carried the weakest evidence in the whole review, rated low or very low certainty. A number built on three small trials isn’t the same as one built on thirty.
The Price of Bigger Losses
The drugs that melted the most weight were also the hardest to stay on. People quit over side effects 1.9 to 4.2 times more often than with lifestyle changes alone. Stomach and bowel trouble was the usual reason. Tirzepatide also took the most lean mass along with the fat, 8.3%. The authors’ summary is blunt: weight loss varies widely, and bigger benefits generally arrive with greater harms. The trials also show the weight returns once treatment stops, so the choice is less about one number after a year and more about what a drug does, and costs, over the long haul.
Key Takeaways
- What the drugs don’t yet show may matter most: no obesity medication convincingly improved quality of life, and only injected semaglutide was linked to fewer deaths (19%), heart attacks (28%) and heart failure (57%), evidence drawn mainly from high-risk patients.
- Tirzepatide produced the largest weight loss, 14.9% of body weight at one year, and halved heart failure risk, but showed no effect on deaths or heart attacks.
- Drugs with bigger weight losses had side-effect dropout rates roughly two to four times those of lifestyle change, and benefits faded after stopping.
References
- Nong K, Shi Q, Xie X, et al. Comparative effects of drugs for adults with overweight or obesity: systematic review and network meta-analysis. BMJ. 2026;394:e372161. link