Sex differences in cognitive restraint and body mass index: the COTASS-2 study

Background Cognitive dietary restraint occurs when an individual monitors and limits their dietary intake to achieve/maintain a certain body weight.  Studies have suggested a genetic component to cognitive restraint and... [ view full abstract ]

Background

Cognitive dietary restraint occurs when an individual monitors and limits their dietary intake to achieve/maintain a certain body weight.  Studies have suggested a genetic component to cognitive restraint and BMI. In addition, sex differences in their aetiologies has been reported in Western populations but not in non-Western populations.  We therefore aim to systematically examine this question in a Sri-Lankan population, using genetic model-fitting analysis. 

Method

3561 individuals were recruited to participate in the Colombo Twin and Singleton Study-Phase 2 (842 monozygotic, 578 dizygotic twin pairs and 2,019 singletons), measuring cognitive restraint and BMI.  Structural equation modelling was conducted to estimate the genetic and environmental contribution.

Results

The phenotypic correlations between cognitive restraint and BMI were significant in both males (0.48, 95% confidence interval: 0.41-0.54) and females (0.47, 95% CI: 0.41-0.52).  Genetic factors play a more significant role in the aetiology of both cognitive restraint and BMI in females (cognitive restraint 45%, 95% CI: 16%-60%; BMI: 77%, 95% CI: 53%-81%) than males (cognitive restraint: 24%, 95% CI: 2%-51%; BMI: 48%, 95% CI: 23%-77%).

Conclusions  

Our results replicate previous findings of a genetic aetiology in cognitive restraint and BMI, with greater genetic effect being observed in females.  Our study illustrates the importance of considering the influence of sex in studies of eating behaviours and BMI.  Further research is needed to clarify whether genetic factors influence cognitive restraint and BMI directly or through inherited mediators, such as impulsivity.