Childhood obesity is associated with host factors that enhance susceptibility and environmental factors that increase food intake and decrease energy expenditure. Obese children underreport food intake and probably consume more food to maintain their weight at increased levels. Prevalence of obesity is related to family variables, including parental obesity, family size and age, and socioeconomic status. Television viewing is strongly associated with the prevalence of obesity through its impact on food intake and activity. How these environmental variables are behaviorally interrelated to the genesis of obesity is unclear.