Body composition and body fat distribution changes after short-term weight gain in anorexia nervosa patients

• Main Author: Orphanidou, Charitini Ioannou
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/3672

The most commonly described psychological abnormality in Anorexia Nervosa (AN) is a distorted perception of body weight and shape. Anorexia nervosa patients typically fear that weight gain is accompanied by preferential fat deposition in the abdomen, hips and thighs; and this fear may contribute to their resistance in gaining weight even when this is of medical necessity. One objective of this study was to investigate body composition and body fat distribution changes that accompany short-term weight gain in AN patients. Another objective was to assess the level of agreement in the measurement of change in percentage body fat in patients with A N pre- and post-weight gain, as determined by two body composition assessment methods: bioelectrical impedance analysis (BIA) and dual energy X-ray absorptiometry (DEXA). Twenty six female subjects, 28+7 years of age (mean + SD), initial BMI17+2 kg/m^, who met the diagnostic criteria for AN completed the study. Subjects were recruited from the inpatient and outpatient Eating Disorders Clinics, St. Paul's Hospital, Vancouver, BC. Body composition and body fat distribution changes were assessed by skinfold (SKF), circumference (CIRC), and DEXA methods. Bioelectrical impedance analysis was used to measure the change in percentage body fat pre- and post-weight gain, and this change was compared to that obtained by DEXA. Skinfold and CIRC measurements were performed at 9 body sites; DEXA was used to quantify body fat mass in the subscapular, waist and thigh regions. Measurements by all methods were performed at baseline, and at the point of maximum weight gain. Results of body composition changes included a highly significant weight gain of 6.7+5.3 kg (p < .001). This weight gain was achieved by significant gains in body fat (p < .001), lean body mass (p < .05), and bone mineral content (p < .01). Total body fat was, however, the component which increased to the greatest extent. Analysis of absolute and relative changes pre- and post-weight gain as assessed by SKF and CIRC indicated a greater fat deposition in the central regions (chest, abdomen, hip and thigh) than in the extremities (arm and calf). However, comparison of body fat mass change (kg) in the subscapular, waist and thigh regions as measured by DEXA indicated no significant differences among these 3 central regions (subscapular: 1.7+1.2, waist: 1.8+1.3, thigh: 1.5+1.0; p = .10). Comparison of measurement of change in percentage body fat upon weight gain between BIA and DEXA indicated poor agreement between the two methods. It appears that single-frequency BIA may not be sensitive enough to reliably quantify changes in body composition in AN patients. Overall, the preliminary findings of this study suggest that although weight gain in A N patients is accompanied by greater fat deposition in the central regions than in the extremities, there is no preferential fat accumulation in any of the central regions. Therefore, the gynoid fat distribution pattern in these patients is preserved despite renourishment and subsequent weight gain. This also implies that significant weight gain does not predispose these patients to the health risks associated with central body fat distribution.