Trends in waist circumferences in young British children: a comparative study

OBJECTIVE: To compare waist circumference (a measure of central fatness) and body mass index (BMI, a measure of general fatness) between a contemporary cohort and similar aged British children measured in 1987. DESIGN: Comparative study of two cohorts. The first was a cross-sectional survey and the second an ongoing longitudinal survey. SETTING: The cross-sectional study was conducted throughout Great Britain during 1987. The ongoing longitudinal study was conducted in the Avon region between 1995 and 1998. PARTICIPANTS: A total of 1821 children were measured in the cross-sectional study, and around 1000 children were measured in the longitudinal study. Ages ranged between 2 and 5 y. MAIN OUTCOME MEASURES: Waist circumference, height, weight and BMI. Values were expressed as mean+/-s.d. Age-related measures were compared. RESULTS: At equivalent ages, mean waist circumference values were greater in the contemporary children, compared with children measured in the earlier cross-sectional study in 1987 (P<0.05). Although boys from the contemporary cohort had the larger absolute waist circumference measurements, the absolute and percentage differences in waist circumference between the cohorts were greater for the girls. Mean BMI values were slightly but significantly higher in the contemporary children compared with children measured in the earlier cross-sectional study (P<0.05). The proportional increase in waist circumference for each age-sex group generally exceeded the proportional increase in BMI. CONCLUSION: These results suggest that central fatness in young British children has increased over the period of 1987-97 to a greater extent than general fatness. This should be of concern since evidence associates greater central adiposity with adverse levels of cardiovascular risk factors in children. Furthermore, the study highlights important shortcomings of the BMI measurement, in that it provides no information on body fat distribution and can mask true obesity-related risk in children.