BMJ network meta-analysis: biggest fat loss and biggest lean loss come together, and quality of life barely moves

A large evidence review published in The BMJ on 8 July 2026 compared 19 obesity drugs head to head using network meta-analysis, pooling 262 randomized trials with 99,791 participants and follow-up ranging from 12 to 172 weeks ^[1]. The headline finding for patients: the drugs that take off the most weight also tend to carry the most side effects and dropouts, most agents do not meaningfully improve quality of life, and few show cardiovascular benefits ^[1].

What the numbers show

At one year, compared with lifestyle modification alone, moderate to high certainty evidence showed the largest weight reductions with tirzepatide (mean difference −14.9%, 95% confidence interval −16.0% to −13.9%) and cagrilintide-semaglutide, known as CagriSema (−14.8%, −16.9% to −12.7%) ^[1]. Then came oral semaglutide (−10.9%, −12.7% to −9.1%), orforglipron (−9.9%, −12.4% to −7.5%), subcutaneous semaglutide (−9.8%, −10.6% to −9.1%) and phentermine-topiramate (−8.1%, −9.7% to −6.5%) ^[1]. Newer agents — ecnoglutide, mazdutide and retatrutide — may produce similar or greater reductions of 13.1% to 14.6%, but that evidence was rated very low to low certainty ^[1].

Body composition told a two-sided story. Tirzepatide reduced fat mass the most, by 25.7%, and also reduced lean mass the most, by 8.3% ^[1]. The analysis reports those figures without concluding what the lean mass loss means for long-term health or function; that question is not answered in this paper.

On hard outcomes, subcutaneous semaglutide was the only drug associated with reduced all-cause mortality (risk ratio 0.81, 0.72 to 0.93) and myocardial infarction (0.72, 0.61 to 0.85) — estimates the authors say were largely driven by cardiovascular outcome trials in high-risk populations, not general populations with obesity ^[1]. Both subcutaneous semaglutide (0.43, 0.21 to 0.84) and tirzepatide (0.49, 0.27 to 0.88) reduced heart failure risk ^[1]. No drug convincingly reduced kidney failure ^[1].

Quality of life was measured across 43 trials with 45,663 participants. No drug improved it beyond established minimally important differences: all mean differences were under 5 points on scales where the minimally important difference is 10 ^[1].

Harms clustered with the more effective drugs. Discontinuation because of adverse events was highest with orforglipron, naltrexone-bupropion, liraglutide, phentermine-topiramate, CagriSema and oral semaglutide, with risk ratios from 1.9 to 4.2 ^[1]. Gastrointestinal events were most increased with naltrexone-bupropion, oral semaglutide, orforglipron and tirzepatide (risk ratios 3.1 to 4.2) ^[1]. Fatigue rose sharply with naltrexone-bupropion (risk ratio 8.9, or 331 more cases per 1,000 people over one year), orforglipron (3.4; 100 more per 1,000) and CagriSema (3.2; 92 more per 1,000) ^[1].

Why it matters for patients

Most drug-by-drug comparisons patients see come from separate trials with different designs. This analysis puts them on one scale using GRADE certainty ratings and the Cochrane Risk of Bias 2 tool, so the trade-offs are easier to see ^[1]. Three practical points stand out.

First, a bigger number on the scale is not automatically a bigger benefit. The authors conclude that larger weight reductions were "generally accompanied by greater harms and discontinuation" ^[1].

Second, the quality-of-life result is a reminder that weight change and how someone feels day to day are measured separately, and in these trials the second did not move much ^[1]. The review does not explain why, and that gap is not resolved here.

Third, the mortality and heart attack findings for subcutaneous semaglutide come mostly from trials enrolling people already at high cardiovascular risk ^[1]. Whether the same size of benefit applies to lower-risk people is not established by this analysis.

Subgroup analyses by drug dose and key patient characteristics did not find credible differences in relative treatment effects, with one exception: trials of longer duration showed larger weight reductions for subcutaneous semaglutide ^[1].

What happens next

The literature search ran through 12 November 2025, and the paper was accepted on 28 May 2026, so trials reported after that window are not included ^[1]. The review notes that CagriSema and mazdutide have shown promising phase 3 results and are under regulatory consideration ^[1]. The BMJ published a linked editorial, "Comparing benefits and harms of obesity drugs," alongside the analysis ^[1]. The review is registered as PROSPERO CRD42024507993 ^[1].