Next generation weight loss drugs leave the original GLP-1s behind

GLP-1 based drugs have reshaped medical weight management, and behind the established GLP-1 receptor agonists sits a wave of newer incretin based treatments and co-agonists. With a growing menu of options and few direct comparisons between them, patients and prescribers lack a clear picture of which drugs deliver the most weight loss and at what cost in side effects. This network meta-analysis set out to compare efficacy and safety across GLP-1 based drugs specifically in adults with overweight or obesity who do not have diabetes, a group in which weight loss itself is the goal rather than blood sugar control.

The authors searched Embase, PubMed and Web of Science for randomised controlled trials published between January 2000 and March 2026. Eligible trials enrolled adults with overweight or obesity, compared a GLP-1 receptor agonist or related co-agonist against placebo or an active comparator, and ran for at least 12 weeks. Trials enrolling people with diabetes, or where diabetes status was unclear, were excluded. In total, 58 trials covering 24 214 participants were combined in a network meta-analysis, a technique that links drugs through their shared comparators so treatments can be ranked even where they were never tested head to head.

Retatrutide produced the largest weight loss versus placebo at 22.10%, followed by tirzepatide at 19.28% and CagriSema, a combination of cagrilintide and semaglutide, at 17.32%. Conventional GLP-1 receptor agonists showed more modest effects. Similar patterns appeared for waist circumference and lipid outcomes. The probabilistic rankings favoured next generation incretin based treatments, although the intervals around several comparisons overlapped, meaning parts of the ordering remain uncertain. On tolerability, low certainty evidence suggested higher rates of discontinuing treatment with danuglipron and retatrutide, while mazdutide showed better tolerability.

Individual trials had already hinted that newer incretin based drugs outperform the original GLP-1 receptor agonists, and this analysis pulls those threads into a single ranked comparison for people without diabetes. It extends the picture beyond weight itself to waist circumference and blood lipids, where similar patterns held. The major limitation is the shortage of head-to-head trials: much of the ranking rests on indirect comparisons routed through placebo. The authors are explicit that differences in tolerability and residual uncertainty should temper any firm hierarchy between these drugs.

If you follow the weight loss drug story, the useful message is that the class is not one thing: in these pooled figures the gap between the newest combined treatments and the original GLP-1 agonists is large. Effectiveness is only half of the decision, though. Dropout rates differed between drugs, and the evidence on tolerability was rated low certainty, so the best performer on the scales is not automatically the easiest to stay on. The comparative rankings could also shift as direct head-to-head trials accumulate.