Assessment of obesity in early childhood.

Measures of physical development were gathered at birth and at ages 3, 5 and 7 years on a sample of over 800 children as part of a multidisciplinary development study. Direct measures of obesity (skinfolds, visual estimate and calculated fat body mass) were correlated with a range of indices based on height and weight (Eid, Ponderal, Quetelet's or Body Mass Index [BMI] and a modified BMI) to determine a valid and reliable index of obesity. Quetelet's or BMI (weight divided by height squared) was found to be the best index of obesity, correlating between 0.88 and 0.96 with percentage fat body mass at ages 5 and 7 years. The BMI also correlated consistently higher indices with all direct measures of body fat than did the other indices. The results indicate that in children, as in adults, BMI can be used to assess obesity simply. It has several advantages, being easy to collect, non-invasive, objective, and requires no special equipment or highly trained personnel. Finally, the BMI, involving as it does only height and weight, can be used to assess obesity retrospectively in the numerous populations which have records of height and weight.