Body Composition Assessment in Adult Females with Anorexia Nervosa and Bulimia Nervosa-A Cross-Sectional Study Comparing Dual-Energy X-Ray Absorptiometry Scan and Isotopic Dilution of Deuterium.

BACKGROUND

Eating disorders (EDs) compromise individuals' nutritional status, affecting, among other organs and systems, bone health.

OBJECTIVES

This study aimed to assess and compare bone mineral density (BMD) from DXA scan and deuterium (DO) dilution of adult females with anorexia nervosa (AN) and bulimia nervosa (BN).

METHODS

This was a cross-sectional study with 53 female participants (18-49 y) with a diagnosis of AN (n = 25) or BN (n = 28). DXA scan was performed to assess BMD, FM, and FFM, and DO dilution was used to assess total body water (TBW), FM, and FFM. Interviews/questionnaires were used to assess symptoms, illness trajectory, and physical activity. t-test, chi-square test, Pearson's linear correlation, linear regressions, and Bland-Altman analyses were performed, with a significance level of 5%.

RESULTS

TBW below the recommended level for adult females (≥ 45%) was more frequent in BN (60%) compared with AN (21%; P = 0.013). FM index (FMI) (soft tissue only) (t-test P = 0.06), and FFM index (FFMI) (t-test P = 0.08) agreed between DXA scan and DO dilution. Only FFMI did not show systematic bias of proportion (β: -0.2, P = 0.177). The diagnosis of BN, binge-eating episodes, and physical activity in AN were associated with the differences in the methods' results. FMI was positively associated with BMD in AN, and both FMI and FFMI were positively associated with BMD in BN.

CONCLUSIONS

In adult females with EDs, DXA scan and DO dilution achieved agreement for FMI and FFMI. Changes in FM and FFM are important in understanding the mechanisms behind bone loss in EDs. Protocols for body composition assessment in EDs can help to minimize the effect of the ED diagnosis, ED behaviors (that is, excessive exercise and purging behaviors), and weight on the accuracy of measurements.