Body mass index during childhood and adult body composition in men and women aged 56-70 y.

Background: The relation between the change in body mass index (BMI) through childhood and body composition in adult life is important because body composition is known to affect adult health.

Objective: The objective was to examine how the change in BMI throughout childhood is related to adult lean and fat mass.

Design: We examined how the change in BMI in childhood was related to adult body composition in 885 men and 1032 women born during 1934-1944, whose weights and heights during childhood were recorded serially. Adult lean and fat mass were measured by bioelectrical impedance with an 8-polar tactile electrode system.

Results: In these 56-70-y-old men and women, adult lean body mass index (lean mass/height(2); in kg/m(2)) was positively associated with BMI at birth (0.24 and 0.20 higher for each 1-SD increase in BMI at birth, respectively) and with more rapid gain in BMI from birth to 1 y (0.17 and 0.22), 1-2 y (0.21 and 0.20), 2-7 y (0.44 and 0.46), and 7-11 y (0.32 and 0.26) of age. Fat mass index (fat mass/height(2)) was positively associated with more rapid increases in BMI between 2 and 11 y of age.

Conclusions: Rapid gain in BMI before the age of 2 y increased adult lean body mass without excess fat accumulation, whereas rapid gain in BMI in later childhood, despite the concurrent rise in lean mass, resulted in relatively larger increases in fat mass.