Objective: A longitudinal study was analyzed to clarify relationships between infant lifestyle, obesity, features of family life and adolescent obesity.
Subjects and methods: Subjects in the present study were born between April 1987 and March 1991, in Enzan City, Yamanashi prefecture. Infant height and weight were measured and questionnaires were collected at medical check-ups at 1.5- and 3-year-of age. Adolescent height and weight were measured in April 2000. Obese adolescents were defined as those with on obesity index > or = 20%.
Results: At 1.5-years-of age, 883 responses to the questionnaire were obtained, and 737 subjects were followed to adolescence (83.5%). Mean follow-up period was 10 years 11 months. A high Kaup index at 1.5-years-of age (odds ratio (OR) 2.61; 95% confidence interval (CI) 1.11-6.12) and when 3-years-of age (OR 5.34; CI 2.54-11.23), as well as maternal obesity (OR 5.32; CI 2.67-10.60) represented risk factors for adolescent obesity. Of the lifestyle items, "playing alone inside" at 1.5-years-of age (adjusted OR 3.01; CI 1.01-8.99) and "taking snacks without time constraints" at 3-years-of age (adjusted OR 2.12; CI 1.25-3.61) were additional risk factors. In food items, only low intake of cow's milk displayed a significant relationship with adolescent obesity, the link being negative with an adjusted OR of 0.63 (CI 0.41-0.95). Covariance structural analysis was performed and a causal model was constructed. Maternal obesity, obesity at 3-years-of age, playing alone inside, taking snacks without time constraints, and low intake of cow's milk were all associated with obesity in infancy. Maternal obesity affected methods of answering child demands, in turn affecting snacking habits.
Conclusions: Adolescent obesity displays relationships with maternal obesity, a high Kaup index in infancy, play activity, snacking habits, and intake of cow's milk. Although genetic factors exert a strong influence, these components of infant lifestyle all play a role in the development of adolescent obesity.