Purpose: After a calorie-restricted diet, most people regain most of their lost body weight. The present chapter focuses on two possible psychological explanations for this weight regain (1) as caused by possible side effects of dieting, specifically the disinhibition effect (the overeating by dieters after they abandoned their dietary restraint), and (2) as caused by the fact that most treatments do not address possible causes of emotional eating (EE). Findings: The disinhibition effect, though a robust phenomenon when dietary restraint was measured with the Restraint Scale, could not be replicated with other measures for restraint. This generated a discussion (i) how restraint should best be measured and conceptualized and (ii) whether the disinhibition effect holds true for all dieters or whether it is only found in a subgroup of dieters, the so-called unsuccessful dieters. Unsuccessful dieters combine high dietary restraint with high overeating tendencies. It is further noted that the disinhibitor “ego threat” elicits EE. However, disinhibition requires prior inhibition (i.e., restraint) by definition. Because restrained eating may be both cause and consequence of EE, also evidence on possible causes of EE (independent from dieting) is presented, in addition to evidence on EE as marker of atypical depression (the subtype of depression associated with increased appetite and weight gain). Implications for treatment: Side effects of dieting and associations of EE with alexithymia (difficulty in identifying and describing emotions) and atypical depression suggest that treatment of obesity should not automatically consist of prescribing calorie-restricted diets. Instead treatments should match with an individual’s eating style. The DEBQ (Dutch Eating Behavior Questionnaire) enables such matched treatment of obesity.