Rapid weight loss can cause more muscle loss than slow weight loss. The popularity of newer weight-loss drugs that shed pounds quickly has raised concerns among researchers about how this will affect the health of our muscles, which do more than just give us strength.

Skeletal muscles, those attached to bones, have a dual role. Primarily, they provide structure and function and are essential for physical movement, maintaining balance and posture, and strength. Secondly, they have a metabolic function. They are a reservoir for amino acids, essential for the body’s stress response, trauma recovery and infection management. They also regulate blood sugar and produce and store glutamine, which is key to immune function.

When you lose weight, you’re bound to lose some muscle. However, rapid weight loss results in greater muscle loss than slow weight loss. With the widespread use of glucagon-like peptide 1 (GLP-1) receptor agonist drugs, which are very effective in weight loss, researchers were concerned that this rapid loss could adversely affect skeletal muscle health.

Researchers at the Pennington Biomedical Research Center (PBRC), which is affiliated with Louisiana State University, collaborated with researchers from the University of Alberta and McMaster University, both in Canada, to write a commentary that was recently published in the renowned medical journal. The Lancet.

Research suggests that muscle loss with GLP-1 receptor agonist drugs such as semaglutide (Ozempic) and liraglutide (Saxenda) can range from 25% to 39% of total weight lost over 36 to 72 weeks, as indicated by decrease in fat-free mass. Fat-free mass consists of lean mass and skeletal muscle mass. By comparison, calorie restriction typically results in fat-free mass losses ranging from 10% to 30%.

“This substantial muscle loss may be largely attributable to the magnitude of weight loss rather than an independent effect of GLP-1 receptor agonists, although this hypothesis needs to be tested,” the researchers said. “In context, on an annual basis, the loss of muscle mass with GLP-1 receptor agonists is several times greater than what would be expected from age-related muscle loss.”

Researchers say this rapid loss of muscle mass could cause health problems. Previous studies showed that low muscle mass is associated with decreased immunity, increased risk of infection, poor wound healing, physical impairment, poor quality of life, and shorter survival.

“Although data on GLP-1 receptor agonists are sparse, evidence from bariatric and metabolic surgery suggests that muscle loss does not necessarily compromise strength,” the researchers said. “However, strength is only one aspect of muscle importance. In addition to being a functional organ, muscle plays crucial metabolic roles that extend far beyond movement and force. These roles are often overlooked when the effects of weight loss on muscle mass are widely discussed.”

Until further studies are conducted, researchers are calling for a more holistic approach to weight loss treatment, combining GLP-1 receptor agonists with exercise and dietary interventions so that muscle mass is preserved.

“We need to be aware of the side effects we see with new weight loss drugs, such as a person eating less while on medication and not getting the proper amount of vitamins and minerals in their diet,” said Dr. Steven Heymsfield, Professor. of Metabolism and Body Composition at PBRC and lead author of the commentary. “Also, when a person loses weight, they don’t just lose fat, they also lose muscle. We are looking at how this muscle loss can be better managed by consuming an adequate amount of protein along with an optimal amount of exercise.”

The comment was published in the journal The Lancet: Diabetes and Endocrinology.

Source: PBRC