Obesity in 10-year-olds: an epidemiologic study.

With a multifactorial pathogenetic model (heredity versus environment, central nervous control, energy balance, morphology of the fat tissue), an attempt was made by this study to assess the relative importance of the various factors to the origin of overweight and obesity in school children. From an original sample of 972 children followed longitudinally from the ages of 7 to 16 years, and with retrospective weight data from the first year of life, 550 were selected for this study at age 10. Information concerning the children's habits (physical activity and appetite), social conditions, and parental heights and weights were obtained from the parents by questionnaire (response rate 94%). The major results of a multiple regression analysis were: (1) clear-cut sex differences; heredity and physical inactivity having the greatest explanatory power for both overweight and obesity at 10 years in girls, whereas appetite and environmental conditions were more prominent predictors in boys; (2) an analysis of the main predictors of the variable "change in relative weight between 7 and 10 years"--a variable with possible implications for preventive school programs--indicated that markedly inactive only children from lower class families are particularly at risk of developing obesity during the first years at school; and (3) in the absence of all the risk factors considered in this study, obesity does not occur; at the other extreme, even a high risk score still implies a 50% chance of escaping the fate of obesity.