Many people taking glucagon-like peptide 1 (GLP-1) drugs like Ozempic or Wegovy (semaglutide) and Mounjaro (tirzepatide) experience rapid weight loss. “According to a clinical trial of Ozempic, after 68 weeks on the medication, 86.4% of participants lost 5% or more of their body weight, and 69.1% lost 10% or more of their body weight.” While weight loss can bring about health benefits, losing weight rapidly can also cause a decrease in muscle mass, lessen bone density, and lower your resting metabolic rate, leading to sarcopenia — the gradual loss of muscle mass, strength, and function. Data that is raising concern about sarcopenia as it relates to GLP-1 drugs is driven by a small portion of participants who underwent DEXA (dual-energy X-ray absorptiometry), which measures bone mineral density using spectral imaging, said Dr. Karl Nadolsky, endocrinologist and diplomate at the American Board of Obesity Medicine.
“Of this subset, the total mass loss was nearly 14 kg and while nearly 8.5 kg (about 60%) was fat loss, the 5 kg lean mass loss reported was 38%, which is on the high end of what we’d expect,” he told Healthline. “That said, DEXA is certainly imperfect in splicing the details of this body composition change as adipose tissue includes plenty of ‘lean mass.’ Additionally, the placebo group lost more lean mass (-1.83kg) than fat mass (1.37kg), which shows potential error.”
Nadolsky pointed out that rapid weight loss, in general, will reduce resting metabolic rate to some degree.
A systematic review and meta-analysis Trusted Source found that dietary trials with higher protein result in less lean mass loss and more fat mass loss compared to lower protein intake. “Nutrition should also optimize protein in a personalized way,” said Nadolsky. To maximize muscle preservation during active weight loss, Kumar said to focus on consuming 25-30 grams of protein per meal. Adding in strength and resistance training can also help build muscle and offset this problem. Prioritizing sleep and consulting with your doctor are also ways you can take your health into your own hands and avoid this problem.