Like essential hypertension, obesity is not only a chronic condition for many individuals but it is also a heterogeneous condition with many underlying causes and interacting factors. It is generally difficult to treat because it is a chronic problem, success comes slowly, and physicians in practice generally understand the condition rather poorly and do not manage it well. Results from studies of caloric restriction, behavior modification and medication have often been disappointing both to the subjects and their physicians. In practice, dropout rates from exercise programs, as well as various dietary self-help programs have been relatively high.