Increasing Protein Intake Could Help Prevent Muscle Loss

• Increasing protein intake while taking GLP-1 drugs for weight loss could help prevent muscle loss, according to a new study.
• As a common side effect of weight loss, muscle loss could also lead to decreased bone density due to the effects on blood sugar management.
• Experts recommend asking your doctor about increasing protein intake and incorporating strength training into your weight loss plan.

Higher protein intake may be the key to avoiding muscle loss, which often occurs in people who lose weight with GLP-1 medications.

Researchers from Massachusetts General Hospital and Harvard Medical School of Boston offered this advice in a new study presented on July 12 at ENDO 2025, the Endocrine Society’s annual meeting in San Francisco.

The report described a small study of 40 people who lost weight with semaglutide compared to those who lost weight through a conventional diet and exercise program.

After three months, the semaglutide group lost more weight than the conventional group. The percentage of weight loss that was lean muscle mass was similar between the two groups.

Participants receiving semaglutide who lost more muscle mass than others were either older adults, females, or those who ate less protein while following a weight loss protocol.

“Older adults and women may be more likely to lose muscle on semaglutide, but eating more protein may help protect against this,” lead researcher Melanie Haines, MD, a neuroendocrinologist with Massachusetts General Hospital, said in a news release.

While promising, these results have not yet been published in a peer-reviewed scientific journal and may warrant further investigation.

Kais Rona, MD, a bariatric surgeon at MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA, explained that muscle is more easily lost during weight loss than fat. Rona wasn’t involved in the study.

“The amount of energy required from the body to maintain muscle is higher than the amount of energy required to maintain fat. This means that muscle tissue is more susceptible to breakdown,” Rona told Healthline.

“The disproportionately high percentage of muscle loss is a direct consequence of the higher metabolic requirements of muscle in comparison to fat,” he added.

Ozempic (semaglutide) is often prescribed off-label for weight loss, while Wegovy, which also contains semaglutide, is approved by the Food and Drug Administration (FDA) for weight loss.

Zepbound and Mounjaro (tirzepatide) have also emerged as highly effective medications for weight loss. Mounjaro is prescribed off-label for weight loss, while Zepbound is approved by the FDA for chronic weight management.

“These medications are very effective appetite suppressants in addition to reducing food intake by slowing down gut function,” Rona explained.

Therefore, when you eat less due to these medications, he noted, you may consume less protein as a result.

“Proteins are the building blocks of muscle tissue, and inadequate protein intake results in the breakdown of muscle, leading to a decrease in muscle mass,” Rona said.

Rona said a strength and resistance training program is “critical in maintaining muscle,” while taking GLP-1 drugs.

He also recommended a robust intake of protein. “I often recommend patients to have 1.2 to 1.5 grams of protein per kilogram of body weight daily.”

“These two strategies work together to stimulate muscle-protein synthesis and reduce the risk of muscle loss during weight reduction,” Routhenstein told Healthline.

“Lean protein “supports both weight management and muscle maintenance by promoting fullness, helping control appetite, and preserving muscle during weight loss, especially when combined with resistance training,” she explained.

Rona noted that protein is a macronutrient that helps produce “physiologic changes that help promote a healthy weight as well as maintain muscle.”

He added that high protein diets have been shown to reduce hunger, promote satiety, and improve metabolism.

Routhenstein recommended choosing lean sources of animal protein such as:

• skinless poultry
• fatty fish (salmon, sardines, tuna)
• dairy (Greek yogurt)

She said plant-based options include legumes (e.g., lentils or black beans) and soy products (e.g., tempeh or tofu).

Routhenstein emphasized the value of a balanced diet for people trying to lose weight.

“The body also needs healthy fats and carbohydrates to fuel workouts, support hormone function, and promote overall health,” she said. “Relying solely on protein at the expense of other macronutrients can lead to nutrient imbalances and may not support long-term muscle health or disease prevention.”

Rona added that dietary supplements like daily multivitamins could be helpful for some people while taking GLP-1 drugs. “This is something important to discuss with one’s clinician,” he said.

Anyone with chronic health conditions, such as kidney or heart disease, should consult with their healthcare team before making significant changes to their diet.