Losing weight isn’t the whole story when it comes to recovering from anorexia nervosa. A concerning new study reveals that significant muscle loss – up to 20% in strength and size – can linger even *after* someone has regained a healthy weight,impacting everything from daily tasks to long-term health.
“In clinical studies,we typically define weight recovery as a body-mass index of 18.5 or within 95% of their age-predicted norm,” explains Megan Rosa-Caldwell, an assistant professor of exercise science at the University of Arkansas specializing in muscle biology. “Generally, if someone is maintaining a weight above an underweight status, that’s when there’s less medical treatment.”
Muscle Recovery Lags Behind Weight Gain
Does simply reaching a healthy weight truly signal a full recovery from anorexia nervosa? The answer, according to research published in the Journal of Nutritional Physiology, is a resounding no. Rosa-Caldwell and her team conducted a study on rats to simulate the effects of anorexia and subsequent recovery.
The researchers restricted the rats’ food intake to mimic the weight loss seen in anorexia nervosa,followed by a refeeding period designed to simulate five and 15 months of recovery in humans,aligning with common inpatient and outpatient treatment durations. thirty days of recovery corresponds to roughly two to three years in human terms, acknowledging the differences in lifespan between rats (approximately 22 months) and humans (70+ years).
The research team assessed muscle mass, strength, and protein synthesis rates. A key finding was a roughly 20% reduction in muscle size and strength. Critically, these muscle health deficits didn’t improve during the shorter recovery periods (five and 15 days). Even after 30 days – when the rats had regained their initial weight and matched the muscle mass of healthy control animals – a decrease in muscle quality remained, resulting in reduced muscle force per unit of mass.
Researchers also observed changes in protein synthesis signaling, noting that “anabolic signaling cascades appear attenuated following long-term recovery from AN.” In simpler terms,the rats’ ability to rebuild muscle tissue had been compromised.
Implications for Anorexia Treatment
Rosa-Caldwell emphasizes that “musculoskeletal complications are probably lasting longer than people think and should probably be taken into consideration when we think of how to treat these individuals.”
While acknowledging the limitations of extrapolating from rat models to humans, Rosa-Caldwell believes the effects of anorexia on rats may even be *less* severe than in people. Rats, unlike humans, don’t grapple with body image issues and will readily eat when food is available. Anorexia nervosa is often a decades-long battle for humans, frequently interrupted by relapses, with only around 50% achieving sustained recovery.As such, anorexia may be a notably persistent cause of muscle atrophy.
Rosa-Caldwell concludes, “For me, it begs the question of ‘how can we implement interventions to get the muscle back faster?'”
Rosa-Caldwell’s co-authors on the study included Lauren Breithaupt, Ursula B. Kaiser, Ruqaiza Muhyudin, and Seward B.Rutkove.
