Pediatric chronic pain is common and predicts risk for psychological and pain problems into adulthood. Biopsychosocial risk factors for the development of chronic pediatric pain have been examined, but the key health behavior of caloric consumption has not been explored. Adult and animal data suggest that caloric intake is positively related to chronic pain, and that adiposity and stress-related biological factors may serve as potential mediators. This study predicted that among children: 1) adiposity, flattened diurnal cortisol slopes, and caloric consumption are related to chronic pain, and 2) the caloric consumption—pain relation is mediated by elevated adiposity and/or flattened diurnal cortisol slopes. Methods: Twin children (N = 733) were drawn from the Arizona Twin Project sample. Measures included caregiver-reported caloric intake via five daily food diaries (Age-8); adiposity (composite of waist circumference, body mass index, body fat percentage) and diurnal cortisol slopes via three days of salivary cortisol sampling (Age-9); and caregiver-reported monthly chronic pain (Age-10). Results: Multilevel models (accounting for clustering within families) with sex, age, socioeconomic status, puberty, race/ethnicity as covariates, showed that caloric intake predicted greater waist circumference, which in turn predicted elevated chronic pain. However, adiposity, waist circumference, and diurnal cortisol slopes did not mediate the caloric intake-chronic pain relation. Discussion: Consistent with the literature, caloric intake predicted adiposity, and adiposity predicted pain in a diverse sample of children. More comprehensive assessment of behavioral (sleep, diet quality) and biopsychosocial factors (e.g. inflammation, cortisol; injury; catastrophizing) may aid efforts to prevent pediatric chronic pain.