Psychological Correlates of Habitual Diet in Healthy Adults

There are 3 motivations for studying the psychological correlates of habitual diet. First, diet is a major but modifiable cause of morbidity and mortality, and dietary interventions could be improved by knowing the psychological characteristics of consumers of healthy/unhealthy diets. Second, animal studies indicate that diet can impair cognition, stress responsiveness, and affective processing, but it is unclear whether this also happens in humans. Third, certain psychological traits are associated with obesity, but it is not known whether these precede and thus contribute to weight gain. Although many psychological correlates of diet have been identified, the literature is highly dispersed, and there has been no previous comprehensive narrative review. Organized here by psychological domain, studies linking diet with individual differences in perception, cognition, impulsivity, personality, affective processing, mental health, and attitudes, beliefs and values-in healthy adults-are reviewed. Although there is a growing literature on the psychological correlates of fruit/vegetable intake-the core of a healthy diet-consumers of unhealthy diets have characteristics that probably make them less responsive to education-based interventions. Diet may be a causal contributor to depression, and diet is consistently linked to impulsivity and certain personality traits. There are inconsistent and less explored links to perceptual, affective and cognitive processes, with several emerging parallels to the animal literature. Impulsivity and personality traits common to obese individuals also occur in lean consumers of unhealthy diets, suggesting these may contribute to weight gain. Diet-psychology correlates remain understudied even though this could significantly benefit human health.