Objective: To evaluate how a change in the level of leisure-time physical activity from adolescence into adulthood is associated with overall and abdominal obesity at the age of 31 y.
Design: Prospective follow-up study of Northern Finland birth cohort of 1966.
Subjects: In all, a population of 2834 males and 2872 females aged 31 y was studied.
Measurements: At the age of 31 y, overweight was defined as a body mass index (BMI) of 25.0-29.9 kg/m(2) and obesity as a BMI of 30.0 kg/m(2) or more. The cutoff points of waist circumference for mild and severe abdominal obesity were 94.0 and 102.0 cm in males and 80.0 and 88.0 cm in females. The change in the level of physical activity (at least moderately active vs inactive) was evaluated by inquiries conducted at the ages of 14 and 31 y. The odds ratios (OR) and their 95% confidence intervals (CI) obtained from logistic regression were adjusted for maternal BMI before pregnancy, BMI at the age of 14 y, alcohol intake, occupational physical activity, smoking, and, in the case of females, for parity at age 31 y.
Results: Becoming inactive during the transition from adolescence to adulthood was associated with overall overweight in males (OR 1.49, CI 1.18-1.89), overall obesity in males (OR 1.53, CI 0.99-2.37) and females (OR 1.51, CI 0.94-2.44), and with severe abdominal obesity in females (OR 1.80, CI 1.13-2.86). Being persistently inactive from adolescence to adulthood was associated with mild abdominal obesity in males (OR 1.83, CI 1.13-2.95), but not with other obesity measures in either gender after adjustment for confounding factors.
Conclusions: Becoming inactive during the transition from adolescence to adulthood is related to overall obesity in both genders, and to severe abdominal obesity in females at the age of 31 y. The results emphasize the role of continued physical activity from adolescence into adulthood in the prevention of adult obesity.