The importance of muscle preservation in medically induced weight loss

A recent commentary published in the journal The Lancet highlights the critical importance of skeletal muscle mass in the context of medically induced weight loss, especially with the widespread use of GLP-1 receptor agonists. These drugs, praised for their effectiveness in treating obesity, have raised concerns about the potential for significant muscle loss as part of the weight loss process.

Dr. Steven Heymsfield, professor of metabolism and body composition, and Dr. M. Cristina Gonzalez, adjunct and visiting professor of metabolism-body composition, both from the Pennington Biomedical Research Center, joined colleagues Dr. Carla Prado of the University of Alberta, and Dr. Stuart Phillips of McMaster University on writing commentary in The Lancet entitled “Muscle Matters: The Effects of Medically Induced Weight Loss on Skeletal Muscle.”

The authors emphasize that muscle loss, as measured by reduction in lean body mass, may account for 25 to 39 percent of total weight loss over a period of 36 to 72 weeks. This rate of muscle decline is significantly higher than what is typically observed with non-pharmacological calorie restriction or normal aging and could lead to unintended negative health consequences.

Despite the promising metabolic benefits associated with GLP-1 receptor agonists, including improvements in the ratio of fat to lean tissue, the potential adverse effects of muscle loss are receiving increasing attention. Skeletal muscle plays a crucial role not only in physical strength and function, but also in metabolic health and immune system regulation.

A decrease in muscle mass is associated with decreased immunity, increased risk of infections, poor glucose control, and other health risks. The authors suggest that muscle loss due to weight reduction may worsen conditions such as sarcopenic obesity, which is common in obese people and contributes to poorer health outcomes, including cardiovascular disease and higher mortality rates.

Although the short-term effects of muscle loss on physical strength and function remain unclear, the commentary calls for future research to investigate how reductions in muscle mass could improve muscle composition and quality. The authors emphasize the need for a multimodal approach to weight loss treatment, combining GLP-1 receptor agonists with exercise and nutritional interventions to maintain muscle mass.

We need to be aware of the side effects we see with the new weight loss medications, such as a person eating less while on the medications and not getting the right amount of vitamins and minerals from food. When someone loses weight, they not only lose fat, but also muscle mass. We are looking at how that muscle loss can be better managed with the consumption of an adequate amount of protein and an optimal amount of exercise.”

Dr. Steven Heymsfield, professor of metabolism and body composition

This evolving conversation underscores the importance of ensuring that weight loss interventions promote overall health, including muscle maintenance, as part of a comprehensive obesity treatment strategy.