BACKGROUND: Eating behavior may be implicated in the increasing prevalence of overweight and obesity, presumably in relation to easy access to energy-dense and highly palatable foods. OBJECTIVE: The aim of the present study was to disentangle genetic and environmental influences on eating behavior in a population-based cohort of male twins. DESIGN: The study included 326 dizygotic and 456 monozygotic male twin pairs aged 23-29 y from Sweden. The revised 21-item version of the Three-Factor Eating Questionnaire (TFEQ-R21) was used to assess eating behavior. This validated instrument consists of 3 dimensions: cognitive restraint, emotional eating, and uncontrolled eating. Structural equation modeling was used to estimate the heritability of eating behavior. RESULTS: Cognitive restraint was the only TFEQ-R21 scale that significantly correlated with BMI (r = 0.39, P