Excess weight and obesity are defined by the WHO (World Health Organization) as abnormal or excessive fat accumulation that is unhealthy.1 On the other hand, attention deficit hyperactivity disorder (ADHD) is defined by the presence of attention difficulties, poor motor regulation activity, and low impulse control.2 The association between obesity and ADHD has been systematically investigated for twelve years. In this review article, previous studies that were relevant in establishing this relation are examined. Neurobiological hypotheses about the relation between obesity and ADHD are reviewed, and an association with addictions is considered.