Rapid weight loss can cause a greater loss of muscle mass than losing weight slowly. 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, the ones attached to bones, have a dual role. First, they provide structure and function and are essential for physical movement, maintaining balance and posture, and strength. Second, they have a metabolic function. They’re a reservoir for amino acids, crucial to the body’s stress response, trauma recovery, and infection management. They also regulate blood glucose 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 a greater loss of muscle mass than losing weight slowly. With the widespread use of glucagon-like peptide 1 (GLP-1) receptor agonist drugs, which are very effective at shedding weight, researchers were concerned that this rapid loss could negatively affect skeletal muscle health.
Researchers from 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 author a commentary piece 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 decreases in fat-free mass. Fat-free mass consists of lean mass and skeletal muscle mass. By comparison, restricting calories typically results in losses of free-fat mass ranging from 10% to 30%.
“This substantial muscle loss can be largely attributed to the magnitude of weight loss, rather than by an independent effect of GLP-1 receptor agonists, although this hypothesis must be tested,” said the researchers. “In context, on an annual basis, the decline in muscle mass with GLP-1 receptor agonists is several times greater than what would be expected from age-related muscle loss.”
The researchers say this rapid muscle mass loss could cause health issues. Previous studies have shown that low muscle mass is associated with decreased immunity, increased risk of infections, poor wound healing, physical impairment, poor quality of life, and shorter survival.
“Although data on GLP-1 receptor agonists is scarce, evidence from bariatric and metabolic surgery suggests muscle loss does not necessarily compromise strength,” the researchers said. “However, strength is only one aspect of muscles’ importance. In addition to being a functional organ, muscle plays crucial metabolic roles that extend far beyond movement and strength. These roles are often overlooked when broadly discussing the effects of weight loss on muscle mass.”
Until further studies have been conducted, the 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 have to be mindful of the side effects that we are seeing with the new weight loss medications, such as a person eating less while on the medications and not getting the appropriate amount of dietary vitamins and minerals,” said Dr Steven Heymsfield, professor of metabolism and body composition at PBRC and the commentary’s senior author. “Also, when a person loses weight, they are not only losing fat, they also lose muscles. We are looking at how that muscle loss can be better managed with consumption of an adequate amount of protein along with an optimum amount of exercise.”
The commentary was published in the journal The Lancet: Diabetes and Endocrinology.
Source: PBRC