The worldwide epidemic of obesity in adolescents.

There is an epidemic of obesity affecting adolescents worldwide. Both in developing and in developed countries, adolescents are increasingly becoming more obese. The number of adolescents exceeding previously identified cut-points as well as the weight and fatness of the most obese individuals is increasing at a progressive rate. Despite their benign appearance, epidemics of noncommunicable disease (or their risk factors) are no less devastating to the health of populations. The two key responses to any epidemic are to discover the causes of the epidemic disease and to characterize the epidemic. The latter needs to occur in relation to prevalence, distribution across the populations (are some population groups more likely to be affected than others?), and secular trends. This chapter reviews what is currently known about the epidemiology of overweight and obesity among adolescents throughout the world. To clarify terms of epidemiology, this chapter first identifies what are considered the most appropriate measures of adiposity and defines how much fat is too much fat.