Two syndromes of obesity following hypothalamic injury, one which results from hyperphagia and one from disordered control of metabolism by the autonomic nervous system. Cushings disease and the polycystic ovary syndrome are two endocrine causes of obesity. A high intake of dietary fat readily produces obesity in experimental animals, but the data in humans are less convincing. A sedentary lifestyle is an important factor in the obesity of the aging. Phenothiazines, tricyclic antidepressants, glucocorticoids, and some anticonvulsants can cause weight gain.
Genetic factors operate through single genes or multiple genes.
The discovery of leptin, the product of the ob-gene has opened a new vista for the study of genetics in obesity as have the genome mapping systems. Obesity, central fat deposition and weight gain in adult life all enhance the risk of early mortality, cardiovascular disease, diabetes mellitus and some forms of cancer. Intentional weight loss will lower the risk of excess mortality from all of these causes. Over the last 20 years the management of obesity has been dominated by the results of clinical trials which lasted only for weeks. Such short trials were conducted because doctors are used to rapid drug effects, such as with blood pressure, liver damage or glucose control.