Ozempic could be hurting your gym gains — with potentially dangerous consequences

The popular weight loss drug Ozempic has been used by millions of Americans for years. Now, researchers warn that the drug has shown some concerning impacts to muscle mass and strength in mice.

New findings suggest muscle mass is altered less than expected while taking the diabetes drug, but that muscles may still get weaker over time. Ozempic-induced weight loss decreased lean mass — or muscle mass without fat — by around 10 percent, the University of Utah Health team said.

Most of that weight loss was from tissue and the liver; the organ shrunk by nearly half its size. Some skeletal muscles, which are attached to bones and responsible for movement, also shrank, while other muscles remained the same size as before Ozempic.

“In clinical trials for Wegovy or Ozempic we did not specifically study the medicine’s impact on muscle mass. In a sub-study of 140 patients with a BMI of 40 or less conducted as part of the STEP 1 trial, dual-energy x-ray absorptiometry (DEXA) analyses suggested that treatment with Wegovy® was accompanied by reductions in both fat mass and lean body mass, with a greater reduction in fat mass than lean body mass,” a spokesperson for Novo Nordisk told The Independent on Tuesday.

“We recommend that any patients experiencing side effects while taking Wegovy or Ozempic contact their healthcare provider,” they said.

Muscle and strength loss in human aging, also known as sarcopenia, can result in trouble with balance and walking, according to the Cleveland Clinic. It’s a condition often linked to obesity, osteoporosis, arthritis, and chronic diseases, including cancer.

Still, the study was done in mice and not humans. More research needs to be done to understand if similar changes to organ size could happen in humans and if there are any associated health risks. Notably, loss of organ mass, including the liver, is expected as a part of healthy weight loss, without affecting the organs’ function. loss of fat can also result in loss of muscle without affecting the overall quality of life, the researchers noted.

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“If we want to really help the individuals who may be losing muscle mass, then we need to know that they’re actually losing muscle mass,” Dr. Katsu Funai, an associate professor of nutrition and integrative physiology in the University of Utah College of Health, said in a statement. “We have data in mice that suggest that things are not as straightforward as they might seem.”

But, it’s not just muscle mass that was affected. In tests of force and strength, some of the mice muscles’ strength decreased as they lost weight — even without losing muscle mass. But, in others, strength was unchanged. Why this happens is not yet understood, but in older humans, losing strength while taking Ozempic could be particularly worrisome.

“The loss of physical function is a strong predictor of not just quality of life but longevity,” Funai said.

Of course, previous research has found Ozempic to have more beneficial side effects, in addition to helping address the nation’s obesity epidemic. A new study linked Ozempic to slower rates of aging, according to New Scientist. That builds on similar research released last year. The drug has also been tied to a reduced risk of dementia in people with type 2 diabetes, and protection against heart disease. Ozempic has not been approved by the U.S. Food and Drug Administration.

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Regardless of their findings, the researchers warned people not to draw hasty and unfounded conclusions. In people, for example, obesity is associated with less physical activity, whereas mice don’t become less active. Humans also become overweight for a multitude of factors, including genetics and age. For mice, it was because they ate a diet that was high in fat.

“There remains a significant need for validation in humans, especially concerning muscle strength,” Dr. Takuya Karasawa, a postdoctoral researcher at the university’s molecular medicine program, said.

The results were published Tuesday in the journal Cell Metabolism.