This article critically reviews the behavioral and biological associations of dietary restraint. Behaviorally, dietary restraint manifests itself in the form of less variety in the diet and reduced energy intake. As practiced by some, dietary restraint may create biological and psychological feelings of deprivation that lead to greater reactivity to food cues, cravings, counterregulation, disinhibition, periodic overeating, and weight gain. Biologically, it is often associated with unhealthy changes in body composition, hormonal changes, reduced bone density, menstrual disturbances, and lower resting energy expenditure. Caution is indicated in the promotion of dietary restraint as a general principle for managing weight.