Brain size, body size and longevity.

In this analysis, we bring together two research fields that have never been associated before: the clinical issue 'Quételet's body-mass index and longevity' and the comparative biological issue 'body-brain allometry'. Comparison of medical and biological data supports the view that body mass index is just a one-to-one mapping of the body-brain-energy balance-a biological variable indicating that an individual maintains its systemic energy homeostasis and therefore is likely to perform well in the coming years.

Long-term effects of rapid weight gain in children, adolescents and young adults with appropriate birth weight for gestational age: the Kiel Obesity Prevention Study.

AIM: This study investigates the effect of rapid weight gain in term children, adolescents and young adults born appropriate for gestational age. METHODS: In all, 173 girls and 178 boys aged 6.1-19.9 (12.5 +/- 3.1)years participated. Rapid weight gain (group 1) was defined as a change in weight-SDS (standard deviation score) from birth till two years >0.67, 'no change' as > or =-0.67 and < or =0.67 (group 2) vs 'slow weight gain' as <-0.67 (group 3). BMI-SDS, waist circumference (WC) z-score, fat mass (FM)/fat free mass (FFM; Air-Displacement-Plethysmography), resting energy expenditure (REE; ventilated hood system), cardio-metabolic risk factors, serum leptin and adiponectin were assessed. >90th age-/sex-specific BMI-percentile was defined as overweight. Parental BMI, socio-economic status and lifestyle were assessed as confounders. RESULTS: A total of 22.8% gained weight rapidly, and 15.7% was overweight. Group 1 compared with group 2 and 3 subjects was taller, heavier and had a higher prevalence of overweight (girls/boys: 26.2%/28.9% vs 11.6%/19.0% vs 2.8%/5.0%; p < 0.01/p < 0.05). Concomitantly, a higher WC, %FM and FFM were observed. Rapid weight gain was positively associated with REE (adjusted for FFM) in boys (r = 0.26; p < 0.01), but not with cardio-metabolic risk factors. CONCLUSION: Rapid weight gain was related to increases in height, weight, a higher prevalence of overweight and central fat distribution. In addition, rapid weight gain was related to a higher REE in boys, but not to cardio-metabolic risk factors.

Determinants and impact of sleep duration in children and adolescents: data of the Kiel Obesity Prevention Study.

BACKGROUND/OBJECTIVES: This study investigates determinants of sleep duration and its impact on nutritional status, resting energy expenditure (REE), cardiometabolic risk factors and hormones in children/adolescents. SUBJECTS/METHODS: In 207 girls and 207 boys (13.0+/-3.4 (6.1-19.9) years) body mass index standard deviation score (BMI SDS), waist circumference (WC) z-score, body composition (air-displacement plethysmography), REE (ventilated hood system; n=312) and cardiometabolic risk factors/hormones (n=250) were assessed. Greater than 90th percentile of BMI/WC references was defined as overweight/overwaist. Sleep duration, media consumption (TV watching/computer use), physical activity, dietary habits, parental BMI, socio-economic status and early infancy were assessed by questionnaire. Short sleep was defined as <10 h per day for children <10 years and otherwise <9 h per day. RESULTS: Total 15.9% participants were overweight, mean sleep duration was 8.9+/-1.3 h per day. Age explained most variance in sleep (girls: 57.0%; boys: 41.2%) besides a high nutrition quality score (girls: 0.9%) and a low media consumption (boys: 1.3%). Sleep was inversely associated with BMI SDS/WC z-score (girls: r=-0.17/-0.19, P<0.05; boys: r=-0.21/-0.20, P<0.01), which was strengthened after adjusting for confounders. Short vs long sleep was associated with 5.5-/2.3-fold higher risks for obesity/overwaist (girls). After adjusting for age, REE (adjusted for fat-free mass) was positively associated with sleep in boys (r=0.16, P<0.05). Independently of age and WC z-score, short sleep was associated with lower adiponectin levels in boys (11.7 vs 14.4 microg/ml, P<0.05); leptin levels were inversely related to sleep in girls (r=-0.23, P<0.05). Homoeostasis model assessment-insulin resistance (r=-0.20, P<0.05) and insulin levels (r=-0.20, P<0.05) were associated with sleep (girls), which depended on WC z-score. CONCLUSIONS: Age mostly determined sleep. Short sleep was related to a higher BMI SDS/WC z-score (girls/boys), a lower REE (boys), higher leptin (girls) and lower adiponectin levels (boys).