Body composition and energy expenditure in response to physical activity in 1.5-year-old children studied by means of the doubly labeled water method

• During recent decades the prevalence of overweight and obesity in childhood has increased and studies of the mechanisms involved are motivated. Previous research has shown a correlation between total body fat (TBF) (%) and physical activity level (PAL) but the assessment of PAL has often involved a risk for spurious correlations. Thus we compared PAL calculated using basal metabolic rate (BMR) predicted from equations, based on body weight (PALBMR) and associated with a risk for spurious correlations, with PAL calculated using sleeping metabolic rate (SMR) assessed using indirect calorimetry (PALSMR) in 20 healthy children aged 1.5 years. Total energy expenditure and body fatness were assessed using the doubly labelled water method. Body fatness of these children was also assessed at one week and three months of age. PALBMR was significantly (r=-0.48, p=0.03) correlated with TBF (%) while PALSMR was not. Furthermore, the increase in body fatness between three months and 1.5 years was significantly (r=-0.52, p=0.02) correlated with PALSMR at the age of 1.5 years. Our results indicate complex relationships between body fatness and physical activity in early life. When conducting studies in this area, resting energy metabolism should be measured rather than predicted using equations based on body weight.

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MEDICINE

MEDICIN

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