Making sense of metabolic obesity and hedonic obesity

Metabolic obesity and hedonic obesity. In a disease state (obesity), when either the metabolic regulation system or the reward system is impaired, weight gain becomes “permanent” and body weight is maintained at the abnormally elevated level (obese weight). (a) Impairments in the metabolic system, as exemplified by leptin resistance (see text for details), cause an upward shift of the set point (green arrow) and result in metabolic obesity, in which the obese body weight is metabolically defended just as normal body weight is. (b) In contrast, disorders in the reward system that cause persistent overeating result in hedonic obesity, in which the obese weight is maintained as a result of a new balance between hedonic overeating (a dominant force; yellow arrow) and the relatively smaller homeostatic forces (depicted here is the adaptive increase in energy expenditure in an attempt to restore body weight; dashed blue arrow). A major environmental culprit of both metabolic obesity and hedonic obesity is believed to be chronic exposure to processed foods high in fat and sugar (see text for details). Metabolic and hedonic obesity may coexist in some individuals if they are predisposed to both conditions; this is not elaborated here for the sake of simplicity. Highlights Body weight normally oscillates around a set point because of a constant “tug of war” between homeostatic and non‐homeostatic forces governed by multiple regulatory systems affecting caloric intake and energy expenditure. Metabolic obesity develops when the body weight set point becomes abnormally elevated, whereas hedonic obesity results when consistent overeating, usually due to impairments in the reward system, overrides the homeostatic regulation. Successful treatment of obesity relies on our ability to better stratify our patients and tailor our treatments.