Prediction of body composition in anorexia nervosa: Results from a retrospective study

Summary Background & aims The assessment of body composition is crucial in evaluating nutritional status in female subjects with anorexia nervosa (AN) and improving their clinical management. The aim of this retrospective study was to assess the accuracy of selected BIA (bioimpedance analysis) equations for fat-free mass (FFM) in female AN subjects and to formulate a specific equation for these subjects. Methods Eighty-two restrictive female AN subjects (age 20.5 ± 3.7 yrs, BMI 15.7 ± 1.7 kg/m 2 ) were studied. Body composition was determined with dual-energy X-ray absorptiometry (DXA) and estimated by BIA using five different equations. Linear correlation analysis was carried out to evaluate the association of FFM with selected variables. Multiple regression analysis was used to formulate specific equations to predict FFM in AN. Results All predictive equations underestimated FFM at the population level with a bias from −5.6 to −11.7%, while the percentage of accurate predictions varied from 12.2% to 35.4%. More interestingly, multiple regression analysis clearly indicates that, in addition to weight, ZI 100 or RI also emerged as independent predictors of DXA-derived FFM, increasing the prediction power of the equation well above that observed with anthropometric characteristics only. Conclusions This study shows that the selected predictive BIA equations considered exhibit an insufficient accuracy at the population and the individual level. Predictive formulas based on body weight plus BIA parameters such as RI and ZI 100 offer a rather accurate prediction of FFM (with high R squared)

Body composition changes in patients with anorexia nervosa after complete weight recovery.

ABSTRACT OBJECTIVE: To assess body composition changes occurring in female anorectic patients after complete weight recovery. DESIGN: Longitudinal study. SUBJECTS: : Ten female patients with anorexia nervosa (age at baseline: 19.7+/-5.8 y) were studied both when undernourished (body mass index, BMI 14.8+/-1.3 kg/ m(2)) and after the achievement of a BMI >18.5 kg/m(2). The control group comprised 18 well-nourished women (age 20.1+/-4.4 y; BMI 19.0-23.0 kg/ m(2)). INTERVENTIONS: Fat mass and fat-free mass were determined by dual-energy X-ray absorptiometry. Skinfold thicknesses and circumferences were also measured. Arm muscle area and arm fat area were calculated by standard formulas. RESULTS: The undernourished patients had lower fat-free mass, fat mass, skinfold thicknesses and circumferences. After refeeding, fat mass represented 25-71%(mean 56%) of the mass regained, this percentage being directly related to the extent of weight gain. The increases in skinfolds and circumferences depended upon the site considered and were correlated to a various extent with those in weight or BMI. Skinfolds at biceps and abdominal sites and the waist-to-hip ratio remained significantly higher, whereas arm muscle circumference was significantly lower, in the refed group than in the control one. CONCLUSION: The percentage of fat in the weight regained by refed female anorectic patients was directly related to the extent of body mass increase. Refed anorectic patients appear to preferentially regain fat in the abdominal and triceps regions. Abnormalities in skinfolds (at biceps and abdominal sites), arm muscle area and waist-to-hip ratio still persist in refed anorectic patients in comparison to control healthy controls

Segmental bioimpedance analysis in professional cyclists during a three week stage race

Bioelectrical impedance analysis has been widely used in the clinical and sport areas because it is a safe, non-invasive, rapid and inexpensive technique that evaluates some electrical properties of the body, such as resistance (R), reactance (X c ) and phase angle (PhA). The aim of this study is to evaluate body composition changes in professional cyclists, participating at the Giro D'Italia 2012, a three week stage race, and in particular PhA modifications as an expression of fat free mass nutritional status. Data were collected at the beginning, in the middle and at the end of the competition. Body weight, circumferences, skinfold thickness and BIA variables (total and segmental body) were measured. Body composition, measured by skinfold thickness, changed during the competition: fat free mass increased, but not significantly, in the middle and at the end of the competition, whereas fat mass significantly decreased versus the baseline in the middle and at the end of the competition. The total PhA did not significantly change in the middle of the competition but was significantly reduced at the end. The arm PhA did not change significantly at both times of the competition, whereas a significant reduction was reported for leg PhA in the middle and at the end of the competition. These results suggest the use of bioimpedance analysis, in particular PhA measurement, to monitor athletes' fat free mass characteristics during medium- and long-term competitions