Obesity in the 21st century.

United States is in the midst of an epidemic of obesity. Children and adults alike are increasing in girth at rapid rates. In the past four decades, the prevalence of childhood overweight, characterized by a body mass index greater than the norm for the 85th percentile, has risen by nearly 4-fold and continues to rise with each year (Ogden et al. 2002). Fifteen percent of children today are overweight according to the most recent national survey (Ogden et al. 2002). Our national goal for Healthy People 2010 (U.S. Public Health Service 2000) is to halt this increase and reduce childhood overweight to a baseline level of 5%, the prevalence nearly three decades ago in the 1970s. Much work remains to be done if we are to achieve this goal. A better understanding of the etiology of this growing epidemic is necessary to prevent and combat obesity. Obesity begins early; obesity in childhood is a strong predictor of obesity in adulthood (Dietz and Gortmaker 2001). According to a recent survey by the New York City Department of Health and Mental Hygiene, 21% of New York City kindergartners are obese (New York City Department of Health and Mental Hygiene 2003). Minorities are disproportionately affected. Studies on obesity consistently report a higher prevalence of obesity in African Americans and Mexican Americans compared with the white, non-Hispanic population.6% of non-Hispanic blacks and 23.4% of Mexican American adolescents were overweight, a startling near-doubling increase (from 13.4% and 13.8%, respectively) in the past decade (Ogden et al. 2002). This contrasts markedly with the prevalence of overweight in non-Hispanic whites of 12.7%. The etiology of obesity is multifactorial. Poor diet and physical inactivity cause overweight and obesity. This imbalance between food intake and energy expenditure is determined, in large part, by the socioeconomic context. Although obesity is affected by interaction between multiple genes and the environment, the genetic pool is not changing rapidly; it is the environmental and social context that has changed and caused the epidemic (Clement and Ferre 2003). Obesity has serious, long-term consequences. The incidence of type II diabetes has increased in U.S. children in parallel with the rising prevalence of obesity (Rocchini 2002). Hypertension, hyper-cholesterolemia, heart disease, asthma, mental health concerns (e.g., depression and low self-esteem), and orthopedic disorders have all been linked to obesity (American Academy of Pediatrics 2003). However, obesity is the single major health problem in the United States that …