Many believe that the hardest part of overcoming anorexia nervosa is gaining weight. Yet recent research shows that the real difficulty may lie elsewhere.
Anorexia prevents proper muscle regeneration
Researchers at the University of Arkansas, led by Megan Rosa-Caldwell, observed the effects of dietary restriction on muscles. To do this, they put rats on a very strict diet for a month. Then, recovery periods (5, 15 and 30 days) were allowed.
Result ? Even when the rats returned to their initial weight, their muscles remained weaker and less bulky than before the diet. Their ability to produce new muscle proteins was also reduced, slowing muscle regeneration.
In a press release, the team specifies that “anabolic signaling cascades appear weakened after long-term recovery from anorexia nervosa”meaning that even after lasting recovery from anorexia nervosa (characterized by a BMI below 17.5), the biological mechanisms that stimulate tissue growth and regeneration do not function optimally.
Why weight gain is not enough
In the treatment of anorexia, weight regain is often considered an indicator of success, particularly when the BMI exceeds 18.5 or the weight reaches 95% of the norm. But as Megan Rosa-Caldwell points out, the body continues to experience effects on muscles long after weight returns to normal.
Thus, even when we “get out of thinness”, appropriate care remains necessary, because “musculoskeletal complications probably last longer than we think and should be taken into account in care protocols”, she says.
This involves not only nutritional monitoring, but also targeted physical activities to rebuild strength and muscle mass. An opinion shared by Dr Christophe de Jaeger, who nevertheless wishes to qualify certain points.
Fat mass is replenished before muscle mass
“First, this is a study done on rats, not humans,” would like to remind the researcher. “This poses a major difficulty: the results are not directly transposable. On a physiological level, when a subject is anorexic, they put themselves in a situation of caloric deficiency. This situation leads to a loss of fat mass, and when fat mass is depleted, muscle mass begins to decrease.
Then, when you gain weight, it is mainly the fat mass that is replenished, and not the muscle mass. This means that the percentage of fat mass increases with each diet… ultimately favoring various metabolic disorders: “hypercholesterolemia, insulin resistance, hypertension, fatigue, etc..
Anorexics are also often “far too weak to practice physical activity”, would like to emphasize the doctor.
Faced with these numerous shortcomings, “Hormonal deficiencies set in, affecting the hormones needed to build bones and muscles, further reducing muscle functionality. he specifies.
Focus on body composition rather than just weight
Despite everything, the doctor admits that this study, although it was carried out on rats, offers interesting lessons for human medicine. “It particularly highlights the strong dissociation between body weight and body composition. Too often, we rely solely on weight, which is insufficient. Two people can weigh the same weight but have very different body compositions: one with little fat mass and a lot of muscle mass, the other with the opposite,” says the doctor.
Today, it would therefore be better to focus on body composition rather than overall weight. In the context of anorexia, an analysis of body composition generally shows an almost total loss of fat mass and marked sarcopenia, reveals the researcher.
“Reestablishing appropriate nutrition and physical training is then essential. Even if patients are weak and often lack motivation, exercise is crucial to preserve muscle mass.”
These good practices considerably increase the chances of regaining “healthy” muscles in the long term. In conclusion, this study reminds us of the importance of physical exercise, even in an already weakened body. “It is all the more essential to protect the muscle compartment, as it is vital for long-term health,” concludes Dr Christophe de Jaeger.