Weight and weight gain are certainly multiply determined. Adiposity varies as a function of age, sex, and socioeconomic status (Ogden et al., 2006; Yach et al., 2006), and, genetically, the fat mass and obesity associated (FTO) gene has been consistently associated with BMI (Frayling et al., 2007; Scuteri et al., 2007). In addition to these demographic and genetic influences, psychological processes contribute to an individual’s waistline. Eating can be a form of emotion regulation (Evers, Stok, & de Ridder, 2010), the inability to resist cravings contributes to binge eating (Rush, Becker, & Curry, 2009), whereas self-discipline is required to exercise regularly (Hoyt, Rhodes, Hausenblas, & Giacobbi, 2009). This line of evidence suggests that weight is a physical manifestation of processes inherent to an individual’s characteristic ways of thinking, feeling, and behaving. Thus, body weight is, in part, a reflection of the processes that define common personality traits.
