The pathway from personality traits to weight gain is likely complex and mediated by physiological mechanisms, as well as behavioral ones. In particular, greater physiological reactivity to stress may also contribute to increases in adiposity. Neuroticism-related traits are associated with greater cortisol reactivity (Mangold & Wand, 2006; Tyrka et al., 2008), and such reactivity may lead to weight gain (Vicennati, Pasqui, Cavazza, Pagotto, & Pasquali, 2009). Likewise, antagonistic individuals have a reactive and sustained physiological response to acute stress. Following an acute stressor, for example, antagonistic individuals show a sharp increase in blood pressure and circulating interleukin-6 (a marker of inflammation), which remain elevated long after the stressor has been removed (Brydon et al., 2010). Such inflammatory stress responses may be implicated in weight gain (Engström et al., 2003).
