A new study shows that drugs in the diabetes drug Mounjaro, combined with a strengthened diet and exercise, can help obese or overweight patients lose at least a quarter of their body weight, an average of about 60 pounds.
In contrast, a group of people who also dieted and exercised but then received dummy injections initially lost weight but then gained some back, the researchers reported Sunday in the journal Nature Medicine.
“This study shows that if you lose weight before you start taking the medication, you can lose more weight after taking the medication,” said Dr. Thomas Wadden, an obesity researcher and professor of psychology at Penn State who led the study.
Outside experts said results presented Sunday at a medical conference confirmed that the drug made by Eli Lilly and Company has the potential to be one of the most effective obesity drugs ever developed.
“No matter how you slice it, it’s a quarter of your total body weight,” said Dr. Carolyn Appovian, who treats obesity at Brigham and Women’s Hospital and was not involved in the study.
The injectable drug tezeparatide was approved in the United States in May 2022 to treat diabetes. Sold as Mounjaro, it has been used “off-label” to treat obesity, joining feverish demand for diabetes and weight-loss drugs including Novo Nordisk’s Ozempic and Wegovy.
All of these drugs, which retail for $900 a month or more, have been in short supply for months.
Tezepatide targets two hormones that are turned on after people eat to regulate appetite and satiety signals communicated between the gut and brain. The drug used in Ozempic and Wegovy, semaglutide, targets one of these hormones.
The new study, funded by Eli Lilly, enrolled about 800 people who were obese or overweight and had weight-related health complications, but not diabetes. On average, study participants started out weighing about 241 pounds (109.5 kilograms) and had a body mass index (a common measure of obesity) of about 38.
After three months of intensive diet and exercise, more than 200 participants dropped out of the trial, either because they had not lost enough weight or for other reasons. The remaining nearly 600 people were randomly assigned to receive either tezeparatide or a placebo as weekly injections for about 16 months. Nearly 500 people completed the study.
During the diet and exercise phase, participants in both groups lost about 7% of their body weight, or nearly 17 pounds (8 kilograms). Patients taking the drug lost 18.4% more than their initial weight, an average of about 44 pounds (20 kilograms) more. People who received the sham injection regained about 2.5 percent of their body weight, or 6 pounds (2.7 kilograms).
Overall, about 88% of patients taking tilsiparatide lost 5% or more of their body weight during the trial, compared with nearly 17% of those taking placebo. Nearly 29% of people who took the drug lost at least a quarter of their weight, compared with just over 1% of those who took a placebo.
That’s higher than the results with semaglutide and similar to results from bariatric surgery, Apovian said.
“We’re doing medical gastric bypass surgery,” she said.
People taking the drug reported side effects such as nausea, diarrhea and constipation more frequently than those taking a placebo. The study found that most of these symptoms were mild to moderate and occurred mainly when the dose of the drug was increased. More than 10% of those taking the drug discontinued the study because of side effects, compared with about 2% of those taking a placebo.
Eli Lilly is expected to release results soon from another study, which the company says shows similarly high weight loss rates. The U.S. Food and Drug Administration has given the company approval for an expedited review of the obesity drug, which Eli Lilly may market under a different brand name. A decision is expected by the end of the year.
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The Associated Press Health & Science Department receives support from the Howard Hughes Medical Institute’s Science & Education Media Group. The Associated Press is solely responsible for all content.
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