Weight Gain, Restoration of Menses, and Bone Density Change in Adolescent Girls with Anorexia Nervosa

Dr. David Herzog—Emeritus Professor of Psychiatry at Harvard Medical School—founded the Harvard Eating Disorders Center in 1994, which later became the Harris Center at Massachusetts General Hospital (MGH).  For over 25 years, Dr. Herzog has collaborated with the Neuroendocrine Unit at MGH to learn more about the biology of eating disorders. This team found that bone loss is a serious complication for most adolescents with anorexia nervosa, placing them at increased risk of debilitating fractures.

 

Dr. Herzog and his colleagues in the Neuroendocrine Unit went on to conduct a prospective, observational study on the effects of weight gain and menstrual recovery on measures of bone mineral density. Sixty-seven girls between the ages of 12 and 18 participated; thirty-four of the girls had anorexia nervosa and 33 were healthy controls. Dual energy x-ray absorptiometry (DXA) was used to measure participants’ lumbar and whole-body bone density at baseline and at 6 and 12 months. 

Weight gain was defined as a 10% increase in body mass index and menstrual recovery as three menses or more in the previous 6 months. The 34 subjects with anorexia were characterized as AN recovered (AN-recovered) if they had both weight gain and menstrual recovery (n=14) and as AN not recovered (AN-not recovered) if they did not have both weight gain and menstrual recovery (n=20). Median duration of recovery was 9 months.

The girls with anorexia had lower spine bone mineral content for bone area and lower whole-body bone area for height, compared with controls.  Weight gain and menstrual recovery in anorexia (AN-recovered) resulted in stabilization of bone mineral density measures, whereas bone density continued to decline in those with anorexia who did not gain weight and resume their menses (AN-not recovered). AN-recovered also predicted greater increases in spine bone mineral content for bone area and whole-body bone area, compared with AN-not recovered.

The data indicate that weight gain and menstrual recovery are associated with a halting of deterioration in bone measures, even in the short term. This raises the question of whether sustained recovery would result in significant increases in bone density parameters. The findings underscore the importance of optimizing weight gain in adolescents with anorexia and highlight the beneficial effects of even short-term weight increase with resumption of menses.