The risk of eating disorders and bone health in young adults: the mediating role of body composition and fitness

Purpose To analyze the independent relationship between the risk of eating disorders and bone health and to examine whether this relationship is mediated by body composition and cardiorespiratory fitness (CRF). Methods In this cross-sectional study, bone-related variables, lean mass, fat mass (by DXA), risk of eating disorders (SCOFF questionnaire), height, weight, waist circumference and CRF were measured in 487 university students aged 18-30 years from the University of Castilla-La Mancha, Spain. ANCOVA models were estimated to test mean differences in bone mass categorized by body composition, CRF or risk of eating disorders. Subsequently, linear regression models were fitted according to Baron and Kenny's procedures for mediation analysis. Results The marginal estimated mean +/- SE values of total body bone mineral density for the categories "no risk of eating disorders" and "risk of eating disorders" were 1.239 +/- 0.126 < 1.305 +/- 0.089, P = 0.021. However, this relationship disappeared after adjustment for any of the parameters of body composition or CRF. Therefore, all body composition parameters (except for lean mass) and CRF turned out to be full mediators in the association between the risk of eating disorders and bone health in young adults. Conclusions Body composition and CRF mediate the association between the risk of eating disorders and bone health. These findings highlight the importance of maintaining a healthy weight and good CRF for the prevention of the development of eating disorders and for the maintenance of good bone health in young adults.