A new study published in the journal Nature Medicine showed that the drug Mounjaro, made by Eli Lilly, can help people who are obese or overweight lose at least a quarter of their body weight, or about 60 pounds on average, when combined with intensive diet and exercise.
The study involved about 800 people who were obese or overweight with weight-related health complications — but not diabetes. On average, study participants weighed about 109.5 kg (241 pounds) at the start and had a body mass index — a common measure of obesity — of about 38.
After three months of intensive dieting and exercise, more than 200 participants dropped out of the study, either because they were unable to lose enough weight or for other reasons. The remaining nearly 600 people were randomized to receive tirzepatide or placebo via weekly injections for about 16 months. Nearly 500 people completed the study.
Participants in both groups lost about 7% of their body weight, or almost 17 pounds (8 kg), during the diet and exercise phase. Those who received the drug lost an additional 18.4% of their initial body weight, or about 20 more pounds, on average. Those who received the dummy injections gained back about 2.5% of their initial weight, or 6 pounds (2.7 kg).
Overall, about 88% of those taking tirzepatide lost 5% or more of their body weight during the trial, compared with nearly 17% of those taking a placebo. Almost 29% of those taking the drug lost at least a quarter of their body weight, compared with just over 1% of those taking a placebo.
This is superior to the results of semaglutide and similar to the results seen in bariatric surgery, said Dr. Caroline Apovian, who treats obesity at Brigham and Women’s Hospital and was not involved in the study.
Side effects, including nausea, diarrhea, and constipation, were reported more frequently in people who took the drug than in those who took a placebo. They were mostly mild to moderate and occurred mainly as the drug dose was increased, the study found. More than 10% of those taking the drug discontinued the study due to side effects, compared with about 2% of those taking a placebo.
Lilly is expected to soon publish the results of another study that the company says shows similar high rates of weight loss. The U.S. Food and Drug Administration granted the company an expedited review of the drug to treat obesity, which Eli Lilly will be able to sell under a different brand name. A decision is expected by the end of the year.
