Higher BMI in early life tied to eating disorders in adolescence
Higher body mass index (BMI) in childhood is likely to increase the risk of disordered eating during adolescence, according to a recent study. In addition, binge eating and overeating in males during early adolescence may lead to higher BMI 5 years later.
“This study provides evidence to suggest a causal effect of higher BMI in childhood and increased risk of disordered eating at age 13 years,” researchers said. “Furthermore, higher levels of binge eating and overeating may cause higher BMI in later life.”
The authors conducted Mendelian randomization (MR) analyses with a genetic score as an instrumental variable for BMI to assess the causal effect of BMI at age 7 years on disordered eating patterns at age 13 years. Data from the Avon Longitudinal Study of Parents and Children (ALSPAC; n=4,473) were used.
Additionally, MR analyses were performed to examine causality in the reverse direction by estimating the effect of the same disordered eating patterns at age 13 years on BMI at age 17 years via a split-sample approach in the ALSPAC. Researchers also investigated the causal direction of the association between BMI and eating disorders in adults via a two-sample MR approach and publicly available genome-wide association study data.
Higher BMI at age 7 years was associated with higher levels of binge eating and overeating, weight and shape concerns, and weight-control behaviour patterns in both males and females and food restriction in males at age 13 years, based on the results of MR analyses. [Am J Clin Nutr 2017;106:764-772]
Moreover, there was evidence showing that higher levels of binge eating and overeating in males at age 13 years could cause higher BMI at age 17 years. There was no evidence of causality between BMI and eating disorders in adulthood in either direction.
“These results encourage the exploration of ways in which to break the causal chain between childhood BMI and later disordered eating patterns, and for the link between binge eating and overeating with later higher BMI,” researchers said.
“Such research could inform and prevent the emergence of disordered eating in adolescence and may, therefore, reduce the incidence of such behaviours and associated metabolic disturbances later in life,” they added.
These findings are in conjunction with several studies that found a causal effect of elevated BMI in childhood and disordered eating later in life. [J Adolesc Health 2015;56:19–24; Nutr Diabetes 2014;4:e100; Dev Psychol 2002;38:669–78; Arch Gen Psychiatry 1998;55:425–32; Behav Res Ther 1997;35:863–73; Eat Behav 2008;9:218–27; J Pediatr Psychol 2013;38:1112–20; Br J Psychiatry 2015;207:320–7]
These findings also support the reverse association of binge eating and overeating in adolescence and higher BMI at age 17 years, which may be caused primarily by loss-of-control eating and binge eating on weight. [Pediatrics 2003;112:900–6; J Consult Clin Psychol 2005;73:195–202]
Furthermore, presence of disordered eating problems (weight control and dietary restraint, similarly to those included in the current study) in early life may result in greater weight among individuals with such behaviours than those without. [Pediatrics 2003;112:900–6; J Adolesc Health 2012;50:80–6; J Am Diet Assoc 2006;106:559–68]
“Therefore, large studies with the ability to explicitly test the causal effect of a range of disordered eating patterns and attitudes on later adiposity, as was done in this current study, would be beneficial to further understand the mechanisms that link these two complex phenotypes,” researchers said.