No abstract

Improvement in body composition and cardiometabolic risk can be seen with BMI SDS reductions of >or=0.25 in obese adolescents, while greater benefits accrue from losing at least 0.5 BMI SDS. The most insulin-sensitive individuals seem best able to effect these changes.

In families of obese children, motivated to seek help by attending a hospital-based weight control clinic, improvements in BMI are possible by a simple approach of education and continued support. Improvement is greatest in younger children with maximal benefit being seen in boys without a parental history of obesity. We believe this emphasizes the importance of identifying significant obesity in primary school aged children, who seem most likely to benefit from simple lifestyle modification, while many older children may require additional intervention programmes to improve BMI.

Objective: To determine which clinical measure of childhood obesity should be monitored to best reflect change in adiposity in a weight management programme and estimate the degree of change needed to be relatively certain of fat reduction. Subjects: 92 obese children with a mean (range) age of 12.8 (6.9-18.9) years and a mean body mass index standard deviation score (BMI SDS) of +3.38 (+2.27 to +4.47) attending a hospital-based clinic on a regular, 3 monthly basis. Measurements: Pairs of weight and height measured up to 2.41 years apart used to derive BMI as kg/m 2 , and adjusted for age and gender to give weight and BMI SDS (BMI-z score) using British 1990 Growth Reference Data. Contemporaneous adiposity estimated by fatness measured by a bioimpedance segmental body composition analyser. Results: Changes in BMI-z scores, compared to BMI, weight and weight SDS, most accurately reflected loss of fat. Reductions of 0.25, 0.5, 0.75, and 1 BMI SDS equate to expected mean falls in total body fat percentage of 2.9%, 5.8%, 8.7% and 11.6%. Approximate 95% prediction intervals indicated that a fall in BMI SDS of at least 0.6 over 6-12 months (or 0.5 over 0-6 months) is consistent with actual fat loss. Conclusion: Change in BMI-z score best reflects percentage fat loss compared to BMI, weight and weight SDS. The wide variation in likely percentage fat loss for a given BMI SDS reduction means a loss of 0.5-0.6 is required to be relatively certain of definite percentage fat reduction.