The epidemic of childhood obesity is attributed to the toxic environment of readily available, calorically dense food and drink. How does this environment interact with the genetic vulnerability to determine who becomes obese? What can this interaction tell us about who becomes obese and at what age they become obese? Answers to these questions could be of great value in preventing childhood obesity. There unfortunately have only been a few longitudinal studies of obesity in children.

Recently, investigators performed a longitudinal investigation of the growth from 3 months to 6 years of age of 70 children, 33 of whom had overweight mothers and 37 of whom had lean mothers. Risk group was defined by prepregnancy maternal body mass index (BMI): greater than the 66th percentile or less than the 33rd percentile for their age group. During the first 2 yr, the size and growth of children in the high- and low-risk groups were almost identical, and there was no relation between maternal and offspring body weights. The current report describes the relation of the risk group to the development of body size and body fat for this cohort from years two through six of life.

At year two, no significant differences in any measure were observed between the high- and low-risk groups. By year four, weight, BMI, and lean body mass were greater in the high-risk than in the low-risk children. By year six, weight was even greater in the high-risk than in the low-risk children (23.4 [+ or -] 6.4 compared with 20.4 [+ or -] 2.1 kg; P < 0.02), and, for the first time, fat mass was greater in the high-risk group than in the low-risk children (6.7 [+ or -] or 5.7 compared with 3.8 [+ or -] 1.2 kg; P < 0.02). Ten of 33 high-risk children exceeded the 85th percentile of BMI at year six compared with 1 of 37 low-risk children (odds ratio = 15.7). Accelerated weight gain was predicted by high-risk group status, greater weight at year two, and lower family income.

While anthropometric measures were not significantly different between groups at year two, weight and lean body mass were greater at years four and six, and fat mass was greater at year six in high-risk children.