Weight-loss drugs work, but scientists still don't agree on why
The Observer looks at why tirzepatide (Mounjaro), which targets both GLP-1 and GIP, beats semaglutide (Wegovy) in trials. One leading researcher argues it's mainly the bigger dose, pointing to newer 7.2mg semaglutide data near 18.7% loss, while others suggest slower desensitisation or a combined effect, and an experimental drug that blocks GIP also causes weight loss.
Source: The Observer (29 Oct 2026). Image: The Observer.