Physical fitness, overweight and the risk of eating disorders in adolescents. The AVENA and AFINOS studies.

UNLABELLED: What is already known about this subject Eating disorders are among the public health issues facing adolescents. An excess of body fat has been associated with an increased risk of these disorders. The association of physical fitness with eating disorders has not yet been analysed in adolescents. What this study adds This study confirms that the overweight and obesity increase the risk of developing eating disorders. The present study shows that there is an inverse association between physical fitness levels and the risk of eating disorders. This study suggests that physical fitness might attenuate the influence of overweight on the development of eating disorders in adolescents.

BACKGROUND: Eating disorders together with the overweight and obesity are important health concerns in adolescents.

OBJECTIVE: To analyse the individual and combined influence of overweight and physical fitness on the risk of developing eating disorders in Spanish adolescents.

METHODS: The sample consisted of 3571 adolescents (1864 females), aged 13 to 18.5 years, from Spain who participated in the AVENA and AFINOS studies. The risk of eating disorders was evaluated using the SCOFF questionnaire. Body mass index was calculated and the adolescents were classified into two groups: overweight (including obesity) and non-overweight according to Cole's cut-off points. Cardiorespiratory fitness in the AVENA Study was assessed by the 20-m shuttle-run test and the overall physical fitness level was self-reported in the AFINOS Study.

RESULTS: Overweight adolescents had a higher risk of developing eating disorders than non-overweight adolescents (odds ratio [OR] = 4.91, 95% confidence interval [CI]: 3.63-6.61 in the AVENA Study and OR = 2.45, 95% CI: 1.83-3.22 in the AFINOS Study). Also, adolescents with medium and low levels of physical fitness had a higher risk of developing eating disorders (OR = 1.51, 95% CI: 1.05-2.16, and OR = 2.25, 95% CI: 1.60-3.19, respectively, in the AVENA Study, and OR = 1.73, 95% CI: 1.37-2.17, and OR = 4.11 95% CI: 2.98-5.65, respectively, in the AFINOS Study) than adolescents with high levels of physical fitness. In both studies, the combined influence of overweight and physical fitness showed that adolescents with lower levels of physical fitness had an increased risk of developing eating disorders in both non-overweight and overweight groups.

CONCLUSIONS: Physical fitness might attenuate the influence of overweight on the development of eating disorders in adolescents.