Body Fat Pattern After Weight Gain in AN

One of the hallmarks of anorexia nervosa (AN) is a distorted view of body image and size. A starved patient feels “huge” in spite of despite dramatic loss of total body fat and muscle. Furthermore, many AN patients feel that if they gain weight, they will gain it all in their waist and abdominal area. Results from a recent study indicate that they may be correct, at least immediately after they regain weight.

Researchers at Columbia University recently studied 29 women with AN and 15 healthy control women between 18 and 45 years of age to test the theory that body fat is irregularly redistributed after AN patients regain weight (Am J Clin Nutr 2005;81:1286). The AN patients were all receiving treatment at the New York State Psychiatric Institute and met DSM-IV criteria for AN, including amenorrhea. Control subjects were thin, healthy, weight-stable, regularly menstruating young women without histories of eating disorders of other psychiatric or medical problems.

All patients were admitted to the hospital for 1 to 2 weeks, during which all women were weighed daily and encouraged to eat food. Liquid nutritional supplements were added if necessary. After one to two weeks of medical and weight stabilization, self-report questionnaires and interviews assessed nutritional intake and activity, as well as body composition.

Researchers used dual-energy x-ray absorptiometry (DXA) to obtain total-body and regional fat and lean soft tissue before and after treatment and once among the control group. Whole-body magnetic resonance imagery (MRI) was also done to evaluate total body and regional adipose tissue and skeletal muscle mass. Serum assays measured cortisol, estradiol, and testosterone levels in both groups.

What the researchers found

Dr. Laurel Mayer and colleagues found distinct differences between the groups after weight gain. At low weight, the waist-to-hip ratio (WHR) of patients with AN and control subjects did not differ. However, after weight was normalized, the WHR of AN patients was significantly greater than that of the control subjects. At low weight, truncal fat as a percentage of total fat in patients was similar to that of control patients, but extremity fat was less among patients than controls.

Hormonal patterns also changed after the patients regained weight. Mean serum cortisol was elevated among the low-weight AN patients compared with controls, while mean serum estradiol levels were reduced. Despite normalization of weight, the average serum cortisol concentration of patients did not change and remained higher than that of control subjects. Serum estradiol levels increased among the AN group with weight gain, but remained below control concentrations when weight was restored. Mean testosterone levels were unchanged with weight gain.

Possible psychological effects

Dr. Mayer and colleagues do not know whether the tendency to accumulate abdominal fat during acute weight recovery has a significantly negative effect upon patients with AN. However, they noted that it is possible that those who gain the most truncal fat and visceral adipose tissue are also the most distressed about body shape and thus more prone to relapse. If this pattern of accumulating fat is only temporary, the patient may reach more normal patterns with long-term weight maintenance. Supportive therapy might help the patient tolerate the temporary body distortion until normal fat redistribution occurs. If, on the other hand, the changes are more permanent, a more targeted cognitive approach might be needed to help patients accept the change in body shape.