Objective: Evidence regarding the relationship between childhood obesity and adult obesity in Japan is limited. This study was conducted to determine the relationship between childhood mass index (BMI) at 3 months, 12 months, 3 years and 20 years in a general population.
Methods: Data obtained from men and women aged 20 years (born between 1968-1974), who had received medical examinations in Ishikawa Prefecture, Japan, were linked to data of medical examinations of the same individuals as infants (3 months, 12 months, and 3 years). The relationship between childhood BMI (or Kaup index) and adult BMI was analyzed for a total of 2,314 participants (1,080 men and 1,234 women), whose data could be followed for 20 years.
Results: BMI at 20 years displayed significant positive correlations with BMI at 3 months, 12 months, and 3 years; this correlation was strongest with respect to BMI at 3 years (r = 0.33, p < 0.001 in men; r = 0.42, p < 0.001 in women). In terms of percentages of obese participants (BMI 25 kg/m2 or over) at 20 years in accordance with BMI categories at each age, the rates were 4.6% in men and 1.0% in women with a BMI less than 15 kg/m2 at 3 years, but 29.1% and 29.5%, respectively, with a BMI of 18 kg/m2 or over (6.3 and 29.5 times higher, respectively). Percentages of obese participants at 20 years were highest in those exhibiting an above average BMI at 3 years, regardless of the BMI at 3 months.
Conclusions: Body mass in young adults is strongly related to body mass in childhood, especially with that at 3 years. About 30 percent of obese children at 3 years remain obese into adulthood. These results are of interest with respect to assessment of future risk of adulthood obesity at medical examinations for infants in Japan.