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Almost one-quarter of U.S. children are now obese, a dramatic increase of over 20% in the past decade. It is intriguing that the increase in prevalence has been occurring while overall fat consumption has been declining. Body mass and composition are influenced by genetic factors, but the actual heritability of juvenile obesity is not known. A low physical activity (PA) is characteristic of obese children and adolescents, and it may be one cause of juvenile obesity. There is little evidence, however, that overall energy expenditure is low among the obese. There is a strong association between the prevalence of obesity and the extent of TV viewing. Enhanced PA can reduce body fat and blood pressure and improve lipoprotein profile in obese individuals. Its effect on body composition, however, is slower than with low-calorie diets. The three main dietary approaches are: protein sparing modified fast, balanced hypocaloric diets, and comprehensive behavioral lifestyle programs. To achieve long-standing control of overweight, one should combine changes in eating and activity patterns, using behavior modification techniques. However, the onus is also on society to reduce incentives for a sedentary lifestyle and over-consumption of food. To address the key issues related to childhood weight management, the American College of Sports Medicine convened a Scientific Roundtable in Indianapolis.

Objective: Inconsistent findings reported for the effect of physical activity on lipids, lipoproteins, and blood pressure in children may be due to errors inherent in the methods used to measure physical activity, lack of control for other cardiovascular risk factors, or both. The purpose of this study was to evaluate the association between physical activity assessed using direct measures of energy expenditure and cardiovascular risk factors, controlling for dietary intake and percent body fat., Methods: Nonresting energy expenditure was determined in 49 8- to 11-year-old girls from measurements of daily energy expenditure (using doubly-labeled water, 2H2(18)O) and resting metabolic rate (using indirect calorimetry). Self-reported recall of the hours of participation in physical activities of at least moderate intensity (energy expenditure at least four times the resting metabolic rate, METS > or = 4) during the previous year was also obtained. Percent body fat was estimated from the measurement of total body water with H2(18)O. Concentrations of total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol (LDL-C), apolipoprotein B (apo B), apo A-I, lipoprotein (a), insulin, and estradiol, as well as the waist-to-hip ratio, systolic blood pressure, diastolic blood pressure, and dietary intake from 7-day food records were measured. Data were analyzed using Pearson product-moment correlation and stepwise multiple regression., Results: Self-reported hours of participation in activities with METS (metabolic equivalents) of 4 or greater significantly predicted LDL-C and apo B concentrations, even after adjustment for percent body fat and percentage of dietary energy from saturated fat. Nonresting energy expenditure adjusted for weight, a measure of the energy spent on physical activity, did not predict LDL-C or high-density lipoprotein cholesterol concentrations. Body mass index and insulin concentration predicted systolic and diastolic blood pressure, respectively., Conclusions: These findings suggest that the intensity of physical activity may be a more important determinant of LDL-C in children than the energy spent on physical activity.

Editorial. Discusses the epidemic of obesity in the United States. How obese people are more prone to chronic diseases such as diabetes and heart disease; Factors that contribute to obesity in adults and children; Need for more public awareness about the dangers of obesity; Why strategies to increase physical fitness must be implemented for the entire population.