Ozempic is just the beginning of a new era in obesity treatment. A review published this week previews the emergence of similar drugs that may be even more effective in helping people lose weight.
McGill University researchers conducted a study, which was a review of clinical trial data surrounding GLP-1 drugs such as semaglutide (the active ingredient in Ozempic and Wegovy). Researchers have confirmed the safety and effectiveness of today’s drugs. But they also highlighted the potential upside of new compounds currently in development such as retatrutide, which has helped people lose more than 20% of their initial body weight in trials so far.
Semaglutide is a synthetic and long-lasting version of the hormone GLP-1—a hormone that regulates hunger and insulin production, among other things. Developed by Novo Nordisk, semaglutide was first approved for type 2 diabetes in 2017 as Ozempic, then for obesity in 2021 as Wegovy. Far from the first GLP-1 drug to reach the public, but semaglutide has been a game changer in the treatment of obesity. It has been shown to help people lose somewhere between 10% to 15% of their weight in studies, well beyond the usual success seen with diet and exercise alone and even surpassing the usual effects of older GLP-1 drugs.
Semaglutide isn’t the only new kid on the block, though. Eli Lilly’s tirzepatide mimics both GLP-1 and another hunger-related hormone called GIP—a powerful combination that allowed it to outclass semaglutide. In clinical trials, people using tirzepatide lost about 20 percent of their initial weight. There are a number of other obesity-related treatments on the way, some of which have reached human trials and are poised to eclipse even tirzepatide.
McGill researchers analyzed data from 26 randomized clinical trials of single-agent GLP-1 drugs, dual agonists such as tirzepatide, and triple-agonist drugs such as retatrutide, which combine synthetic versions of three hunger-related hormones : GLP-1, GIP, and glucagon. These trials involved people living with obesity but without type 2 diabetes.
As expected, they found that today’s approved drugs are generally safe and effective, with tirzepatide currently performing the best (participants lost up to 17% of body weight after 72 weeks of treatment). But they also showed retatrutide to be more effective in the short term, with participants losing up to 22% of their body weight after just 48 weeks of treatment.
“We found that, of the 12 GLP-1 [drugs] identified in our search, significant reductions in body weight have been reported in randomized controlled trials of retatrutide, tirzepatide, and semaglutide,” the researchers wrote in their paper, published Tuesday Annals of Internal Medicine.
Retatrutide is being developed by Eli Lilly, and is now being tested in phase 3 trials—trials that will reach their conclusion in 2026. And it won’t be the only youth coming in the near future who can take out today’s drugs.
Last year, for example, the results of the first trial of the drug amycretin (manufactured by Novo Nordisk) suggested that it could provide greater weight loss than semaglutide and tirzepatide. Other drug companies are working on competitors of Ozempic, such as Boehringer Ingelheim and Zealand Pharma’s dual agonist survodutide. Expectations have been so high that Novo Nordisk’s stock actually fell when they announced that their drug candidate CagriSema (a combination of the experimental drugs semaglutide and cagrilintide) only helped people lose 22% of weight in a recent trial, rather than the 25% expected.
These drugs are not without their problems, of course. They often cause gastrointestinal symptoms such as diarrhea and vomiting, and are linked to rare but serious complications such as gastroparesis (stomach paralysis). Another major concern is their price, with semaglutide and tirzepatide often costing about $1,000 per month without insurance (which is often not covered by private and public insurers). Those costs and growing demand have given rise to a gray and black market for these drugs, with people turning to cheap, but unsafe compounded and counterfeit versions.
Some experts hope that the advent of other GLP-1-related drugs will help alleviate some of these problems, especially cost and insurance coverage. Whether that actually happens, we’ll have to see. But it is almost certain that there will be more drugs to come, semaglutide and the current tirzepatide crown as the best obesity treatments around.