The role of the environment in overweight and eating behavior variability: Insights from a multivariate twin study

Abstract

AbstractThe health consequences of overweight and obesity remain one of the greatest global health challenges. Twin and molecular studies have confirmed the genetic basis of individual differences in BMI; however, genetics cannot explain the rapid rise of obesity rates over the past decades. Eating behaviors have been stipulated to be the behavioral expression of genetic risk in an obesogenic environment. Multivariate twin studies can inform future applied research by providing insights into the etiology of the relationship between behaviors and BMI. In this study, we aimed to decompose variation and covariation between three key eating behaviors and BMI in a sample from a population-based twin registry of adult women in the southeast of Spain, The Murcia Twin Registry (345 complete, 9 incomplete, same-sex female twin pairs, 175 MZ, 170 DZ). Phenotypes were emotional eating, uncontrolled eating, and cognitive restraint, as measured by the Three Factor Eating Questionnaire, as well as objectively measured BMI. Variation in eating behaviors was mostly driven by non-shared environmental factors (range: 56-65%), whereas shared environmental and genetic factors were secondary. All three eating behaviors were associated with BMI at a phenotypic level (range r=0.19–0.25). Etiological correlations implied that non-shared environmental factors underly the covariations of the phenotypes (Emotional eating – Uncontrolled eating: rE= 0.54, 95%CI: 0.43, 0.64; BMI – Cognitive restraint: rE= 0.15, 95%CI: 0.01, 0.28). Results indicate that in contrast to BMI, individual differences in eating behaviors are mostly explained by non-shared environmental factors, which also account for the phenotypic correlation between eating behaviors and BMI. These results support that eating behaviors are viable intervention targets to help individuals reach and maintain a healthy weight.