Obesity is a complex entity that can have many causes, such as endocrine (like thyroid dysfunction or hyperfunctioning of the suprarenall gland-Cushing’s syndrome) but often obesity is from a combination of inactivity and overeating. On the other side, there are genetic factors that produce a tendency to overweight even with the consumption of what would be for most people an appropriate number of calories. Whether the causes are hormonal, genetic or reside in the brain (its reward system or the circuitry that underlies habit, perception of portion size, the choice of food...) is often difficult to sort out. Proponents contend that obesity is a disease because it meets the definition of disease. Obesity decreases life expectancy and impairs...