High energy expenditure is not protective against increased adiposity in children.

BACKGROUND: Low levels of energy expenditure (TEE) may contribute to excess weight during childhood, but limited longitudinal data exist. OBJECTIVES: This is to test whether low TEE during the first 6 years of life could predict excess weight status at 8 years. METHODS: Total energy expenditure from doubly labelled water, weight, stature, waist circumference and fat mass and fat-free mass (FFM) in children at 0.25, 2, 4 and 6 years of age. This cohort includes individuals at high (n = 27) and low risk (n = 26) for childhood obesity, based upon whether pre-pregnant maternal obesity. A linear mixed effects model was fit to TEE. Individual variation was accounted for as a random effect. Residual TEE was calculated for age and individually averaged across time. RESULTS: Fat-free mass (kg) was highly correlated (R2 = 0.91) with TEE (kcal/day), and waist circumference and sex were also significant predictors of TEE. TEE residual tracked within individuals. TEE residuals did not correlate with either BMI or %fat at age 8 years. CONCLUSION: Using the residual TEE approach to identify high and low TEE during the first 6 years of life did not explain excess weight at 8 years of life in this cohort of children at high and low risk of obesity based upon maternal obesity status.

Comparison of total energy expenditure between school and summer months.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: Childhood obesity has increased 3 to 4 fold. Some children gain excess weight in summer. WHAT THIS STUDY ADDS: Total energy expenditure increases almost linearly with fat-free mass. A lower total energy expenditure was not detected in summer. OBJECTIVE: Recent data report that the youth experience greater weight gain during summer than during school months. We tested the hypothesis that a difference in total energy expenditure (TEE) between school and summer months exists and may contribute to summer weight gain. SUBJECTS AND METHODS: A secondary analysis was performed on cross-sectional TEE data from school-age, sedentary African-American and Caucasian youth based in or near the District of Columbia who were at-risk for adult obesity because they had body mass index (BMI) ≥ 85th percentile or had overweight parents. TEE was estimated from 18-O and deuterium measurements during 1-week intervals using urine samples collected after ingestion of doubly labelled water. Differences in summer- and school-time TEE were assessed using analysis of covariance. The data were adjusted for fat-free mass (FFM) as determined by deuterium dilution to adjust for the effect of body size on TEE. RESULTS: Data were collected from 162 youth (average age 10 ± 2 years, BMI 28 ± 8 kg m(-2) and BMI z-score 1.96 + 0.96). Of these, 96 youth had TEE measured during the school year (September-June); 66 different youths had TEE measured during summer months (June-August). After adjustment for FFM, average summertime TEE was 2450 ± 270 kcal d(-1) and average school-time TEE was 2510 ± 350 kcal d(-1) (P = 0.26). CONCLUSION: No difference in TEE was detected between the school year and the summer months. These data suggest that seasonal differences in youth weight gain are not necessarily due to differences in energy expenditures.