Semaglutide has “unexpected” effects on muscle function in mice

This study, which used an experimental mouse model, shows how treatment with high-dose semaglutide led to a loss of muscle strength disproportionate to the modest reduction in lean mass. Therefore, semaglutide, a drug widely used to treat obesity, could influence not only weight loss but also body composition and muscle function. Although the findings cannot be directly extrapolated to humans, they help better understand the mechanisms underlying the loss of lean mass, which in this case was modest and proportional to what is observed in many effective weight-loss interventions, such as bariatric surgery. It is important to remember that lean mass is often increased in obese people, and part of its reduction with this drug could be due to improvements in muscle quality, such as a decrease in fatty infiltration (myosteatosis).

In clinical practice, these results reinforce the message that weight loss should be approached holistically. Obesity is a chronic, complex, multifactorial, and relapsing disease, with few effective pharmacological options until relatively recently. Furthermore, semaglutide specifically has demonstrated not only benefits in weight loss, but also improvement in other obesity-related complications and a decreased risk of cardiovascular events. However, treatments with drugs such as semaglutide must be accompanied by an appropriate nutritional plan—with sufficient protein intake—and an adapted exercise program that includes strength training, in order not only to preserve muscle mass but also to improve its functionality. This approach not only protects muscle mass but also enhances the metabolic and functional benefits of treatment. Inappropriate use of these drugs or without regular monitoring could compromise important long-term health outcomes.