Low Protein Intake Tied to Muscle Loss With Weight Loss Drugs

A new study presented at the Endocrine Society’s ENDO 2025 conference suggests that individuals taking weight loss drugs like Ozempic who consume less protein are more likely to experience greater muscle loss. The findings highlight the importance of diet, specifically protein intake, for people using GLP-1 receptor agonists, a class of medications increasingly prescribed for obesity management.

Rapid weight loss, no matter the method, is known to decrease lean muscle mass, raising the risk of falls, fractures, and metabolic issues, especially in older adults. However, those taking drugs such as semaglutide—the active ingredient in both Ozempic and Wegovy—may be more vulnerable to muscle loss if their protein intake is inadequate.

“Our data suggest that higher protein intake—specifically among participants on semaglutide—may help prevent some loss of lean mass,” said study author Dr. Melanie Haines of Massachusetts General Hospital and Harvard Medical School.

Study Overview

The research involved 40 adults with obesity, none of whom had type 2 diabetes. Twenty-three participants were prescribed semaglutide, while the remaining 17 followed a structured diet and lifestyle plan. After three months, those taking semaglutide lost an average of 6.3% of their body weight, compared to 2.5% in the lifestyle group. Both groups lost comparable proportions of lean muscle, but among those on semaglutide, the biggest muscle loss occurred in older adults, women, and those with lower protein consumption at the study’s start. This group also experienced less improvement in blood sugar regulation when they lost more muscle mass.

Protein Deficiency and Health Risks

Weight loss efforts typically involve fewer calories and, consequently, reduced protein intake. Protein provides essential amino acids to preserve muscle tissue, so cutting back can have unintended consequences. Although the study was not a randomized controlled trial and did not measure exact protein requirements, Haines says the evidence supports the notion that “more protein was better in terms of preventing loss of lean mass.”

Limitations and Further Research

Experts caution that the study is small, lacks peer review, and involved mostly white, female participants—which limits how broadly the results can be applied. Further research is needed to determine the precise role of protein and which types of muscle are most affected during weight loss with these drugs.

Muscle Preservation Strategies

Despite these uncertainties, health authorities widely agree that dietary protein is crucial for maintaining muscle—particularly during weight loss. Dr. Richard Siegel, co-director of the Diabetes and Lipid Center at Tufts Medical Center, recommends patients aim for up to 1.6 grams of protein per kilogram of body weight daily, which translates to 60–120 grams for most adults. Protein-rich foods include seafood, lean meats, poultry, eggs, legumes, soy, nuts, and seeds.

A balanced diet is equally important, with sufficient fat, carbohydrates, and fiber, Siegel notes.

Physical activity, especially resistance training like push-ups, squats, or weightlifting, also helps mitigate muscle loss. Prior research has shown that such exercise protects lean mass, even in patients using GLP-1 medications.

Managing Side Effects

Some people taking GLP-1 drugs may struggle with nausea or reduced appetite, making it tough to eat enough protein or exercise. Dr. Haines recommends gradual dose increases to minimize side effects and encourages patients not to rush to the highest medication dose.

As weight loss drugs become more common, experts stress that nutrition and exercise must remain critical components of safe, effective obesity treatment—especially to protect long-term muscle and bone health. Always consult a healthcare provider for personalized guidance.