Although rapid childhood weight gain has been suggested to be a risk factor for lifetime obesity and other chronic diseases, few studies have been conducted in Asian populations. The aim of this study was, therefore, to ascertain whether rapid childhood weight gain is associated with indices of obesity in adulthood and, if so, which period in early development provides the greatest predictive value of future obesity in young Japanese women.

A total of 86 female university students aged 18–21 years old participated in this study. Current height, weight, body fat percentage (BFP) as evaluated by bioelectrical impedance analysis, and BMI were measured. Body weight at birth, 3 and 6 months, and 1.5 and 3 years of age was obtained from the maternity record book ( Boshi-techo ), and body weight at 6 years was obtained from school health records. We assessed infant weight gain by the weight change Z-score.

Current BFP was found to be significantly correlated with weight change between 0 and 3 months ( r = 0.26, P = 0.034) and between 3 and 6 months of age ( r = −0.28, P = 0.031). However, none of the physical activity indices correlated with BMI and BFP.

Rapid weight gain in early infancy positively associates with BFP in young Japanese women.