[Life style of children and obesity in a population of 5-year-old children].

The increasing level of childhood obesity has prompted some research into the early risk factors likely to lead to preventive measures. A case-control study was conducted of a five year-old population in the Rhône and Isère administrative "départements" of France during the children's first visit to primary school, with the participation of 327 obese children and 704 controls. Anthropometric data on the children since birth, together with data on their lifestyles, were collected in interviews with parents. "Family obesity" and "obesity at birth" were found to be closely related to the child's obesity at five years old (adjusted OR = 2.7 and 2.1 respectively). Of the environmental factors, the hypothesis tested paid specific attention to television viewing, snacks between meals and lack of sleep. These three variables were all found to be risk factors of obesity at five years old. However after allowing for parental obesity, the only remaining significant risk factor for obesity at five was lack of sleep (adjusted OR = 1.4). The pathogenic assumptions raised by these results are discussed.