Storage and expenditure of energy in obesity and their implications for management.

We have seen in the past 20 years intensive investigation of the responses of the obese and the lean to caloric intake and to various environmental stresses. Although there is much discrepancy of results, the following are obvious: Obesity is not a clear-cut syndrome, and individuals differ significantly in their genetic subtypes and in the stages, type, and degree of their metabolic disturbances. A difference in the facultative component of the thermogenic effect of food can explain some of the variation. This in turn is closely related to insulin resistance, which bears a close relationship to subtypes of hypertension and hyperlipidemias. The greatest scope for clinical intervention lies in these fields. Both the obese and the lean subjects are adapted to retain dietary fat independently of the energy needs. The high ratio of fat to carbohydrate in the western diet and, increasingly in that of the east, is cause for concern.