Anorexia Nervosa and Fat Distribution after Weight Recovery

One side effect of regaining weight during treatment of anorexia nervosa (AN) is an accumulation of body fat in the abdomen. This single factor can make some AN patients resist regaining more weight or may even trigger a relapse. Dr. Marwan El Ghoch and colleagues at Villa Garda Hospital, Garda, Italy, performed an extensive literature search to identify clinical studies of adolescents and adults diagnosed with AN who had partial or complete weight restoration. Twenty studies were included in the final analysis (Nutrients 2014; 6:3895; doi:10.3390/mu6093895).

The first study to assess body fat distribution was performed by Forbes in 1990. This cross-sectional study of 30 teenage females with AN used the waist-to-hip ratio (WHR) as a measure of body fat distribution. A reduction in waist and hip circumference was detected but no difference in WHR emerged between adolescents with AN and healthy control patients. The development of dual-energy x-ray absorptiometry (DEXA) scanning 10 years later provided for a more accurate way to assess body composition. The DEXA data from subsequent studies showed that adolescent females with AN tend to lose more central/visceral fat in the trunk than in peripheral areas, while adolescent males with AN tend to lose more peripheral than central fat.

According to the authors, only two previous studies have investigated the effects of changes in body fat distribution on metabolic indexes and AN psychopathology. Prioletta et al. showed that more central fat regain was correlated with higher insulin resistance and lower insulin sensitivity (Clin Endocrinol 2010; 75:202). On the other hand, El Ghoch and colleagues reported that greater central fat distribution after short-term complete weight restoration did not impact eating disorder psychopathology or psychological distress in patients with AN (Am J Clin Nutr 2014; 99:771).

Dr. El Ghoch and his coauthors reported that their review showed strong evidence that abnormal central adipose deposition appears to normalize after long-term maintenance of complete weight restoration. Some prior studies have reported decreased body fat in such patients.

The authors’ evaluation found strong evidence suggesting that adult females with AN lose more peripheral fat than central body fat, while adolescent females with AN lose more central than peripheral body fat. Despite emaciation, both adolescent and adult females retain a basically normal body fat distribution. A second finding was that partial weight restoration leads to greater central fat mass deposition in the trunk region than in other body regions in adolescent females (WTH ratio). Another trend, but one that still requires confirmation, is evidence that the pattern of abnormal central fatty disposition appears to normalize after long-term maintenance of complete weight restoration. Perhaps counterintuitively, evidence suggests that the preferential distribution of body fat in central regions does not worsen eating disorder psychopathology or distress in patients with AN. One small cross-sectional study suggested that adolescent males lose more fat from their extremities than from the truncal area.

And, what if any metabolic consequences associated with abnormal fat deposition after complete or partial weight restoration in these patients? The authors found almost no data on this—only one study reported a connection between the abnormal fat deposits and insulin resistance. If confirmed, this would not be surprising, as central adiposity is associated with cardiovascular disease and insulin resistance.

Weight regain is a central component of AN treatment. The authors point out that much more study is needed, particularly studies examining the longer-term course of fat distribution after weight restoration.