A new analysis compared several GLP-1 medications used for weight loss in adults without diabetes.
Tirzepatide produced the greatest average weight loss, followed by semaglutide and liraglutide.
Researchers say the findings can help patients and providers better understand how these drugs stack up.
GLP-1 medications have transformed the way obesity is treated, with drugs like Wegovy, Zepbound, and Saxenda becoming household names. But while these medications all work by helping people feel fuller and eat less, researchers wanted to know whether some are more effective than others when it comes to weight loss.
A new analysis from researchers at the University of Georgia examined existing clinical trials involving adults with obesity or overweight who did not have diabetes. The goal was to compare the effectiveness and side effects of several GLP-1 medications and determine how they measure up against one another.
“We were interested in finding which drug gives the most weight loss and doesn’t have higher rates of side effects like nausea and gastrointestinal problems. Tirzepatide seems to be the better option,” Pooja Gokhale, corresponding author of the review and a doctoral student in the UGA College of Pharmacy, said in a news release.
The study: A review of earlier clinical trials
Rather than conducting a new experiment, the team performed what is known as a systematic review and network meta-analysis. They searched the scientific literature for randomized controlled trials involving FDA-approved weight-loss medications in the GLP-1 class.
In total, the researchers identified 26 studies involving 15,491 participants. The trials evaluated three medications approved for chronic weight management in adults without diabetes: tirzepatide, semaglutide, and liraglutide. Researchers compared how much weight participants lost while also looking at side effects and treatment discontinuation rates.
Because the analysis combined data from multiple studies, it allowed investigators to compare medications even when they had not been tested directly against each other in head-to-head trials.
The results: Tirzepatide came out on top
The analysis found that tirzepatide produced the largest reductions in body weight, with participants losing more than 20% of their starting weight on average.
Semaglutide was associated with roughly 15% weight loss, while liraglutide led to an average reduction of about 8%. Higher doses generally resulted in greater weight loss across medications.
The researchers also found that gastrointestinal side effects, such as nausea and vomiting, were common across the medications. Tirzepatide had the highest likelihood of producing these side effects, although it also delivered the greatest weight-loss benefits.
Liraglutide was associated with the smallest weight reductions and requires daily injections, unlike the weekly dosing used with tirzepatide and semaglutide.
For consumers, the findings suggest that weight-loss medications do not all perform the same way. While effectiveness is one factor, side effects, dosing schedules, and individual circumstances are also important considerations when choosing a treatment with a healthcare provider.