Risk in childhood of development of severe adult obesity: retrospective, population-based case-cohort study.

Recent studies have shown a weak continuity of fatness from childhood through adulthood within the central part of the population distribution. This study presents body mass index values (weight/height2) from ages 7-13 years for the 429 severely obese young males with a body mass index of at least 31 kg/m2 among 93,800 draftees born between 1930 and 1956 inclusive who attended school and underwent draft board examination in Copenhagen. This group was compared with a random 1% sample from the same draftee population. At age seven years, the obese group already had a much higher body mass index than did the population sample, and the deviation increased as the children grew older. The risk of becoming a severely obese adult increased exponentially over the entire range of body mass index in childhood. Logistic regression analysis showed that 13-year-old overweight children who had either decreased or increased in percentile level since age seven years had a higher risk of developing severe adult obesity than did 13-year-old children who had maintained their percentile level. However, most obese children did not develop severe obesity in adulthood, and only a few had been severely obese throughout.