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Total energy expenditure, body fatness, and physical activity in children aged 6-9 y
E J Ball1, J O'Connor, R Abbott
1James Fairfax Institute of Paediatric Nutrition, The Children's Hospital at Westmead, Westmead, NSW, Australia.
Insights
Childhood obesity may be linked to reduced physical activity. This study found that in boys, higher body fat percentage was associated with lower physical activity levels, but not in girls.
Area of Science:
- Pediatric Endocrinology
- Human Physiology
- Obesity Research
Background:
- Rising global childhood obesity rates suggest a potential link to decreased physical activity.
- Understanding energy expenditure and physical activity in pre-pubertal children is crucial for addressing this trend.
Purpose of the Study:
- To measure total energy expenditure (TEE) using the doubly labeled water (DLW) method in pre-pubertal children.
- To determine the relationship between physical activity, body fatness, and potential sex differences.
- To investigate the proportion of TEE attributable to physical activity.
Main Methods:
- Utilized the doubly labeled water (DLW) technique to measure TEE over 10 days in 106 healthy children (aged 7.8 ± 0.9 years).
- Calculated resting energy expenditure (REE) using Schofield equations and derived fat mass from (18)O dilution space.
- Determined physical activity level (PAL) as the ratio of TEE to REE (TEE/REE).
Main Results:
- Mean TEE was significantly lower than recommended levels for both boys and girls.
- No significant difference in physical activity level (PAL) was observed between boys and girls.
- In boys, PAL was inversely correlated with BMI, fat mass, and body fat percentage; this correlation was not significant in girls.
Conclusions:
- Body fat percentage is inversely associated with physical activity levels in boys, suggesting physical activity influences body fatness.
- Additional factors beyond physical activity may influence fat storage in girls.
- Findings highlight potential sex-specific relationships between physical activity and body composition in pre-pubertal children.
Background:
The recent worldwide increase in the prevalence of childhood obesity may be due in part to a decrease in children's physical activity levels.
Objective:
The current study of children in the years just before puberty aimed to 1) measure total energy expenditure (TEE) by use of the doubly labeled water (DLW) method, 2) determine the proportion of TEE related to physical activity, 3) investigate the relations between measures of physical activity and body fatness, and 4) investigate possible sex differences in these relations.
Design:
The DLW technique was used to measure TEE over 10 d in 106 healthy children (52 boys) aged 7.8 +/- 0.9 y (x +/- SD). Fat-free mass, and hence fat mass, was derived from the (18)O dilution space. Resting energy expenditure (REE) was calculated with use of the Schofield equations. Physical activity level was calculated as TEE/REE.
Results:
Mean TEE in both boys (7871 +/- 1135 kJ/d) and girls (7512 +/- 1195 kJ/d) was significantly different (P < 0.0001) from FAO/WHO/UNU recommendations (13% and 9% lower, respectively). There was no significant difference in physical activity level between boys (1.69 +/- 0.22) and girls (1.71 +/- 0.23). In boys but not girls, physical activity level was inversely correlated with BMI (r = -0.37, P < 0.01), fat mass (r = -0.46, P < 0.005), and percentage of body fat (r = -0.50, P < 0.0001).
Conclusions:
In boys but not girls, percentage of body fat is inversely associated with physical activity level. Physical activity is one factor contributing to body fatness in boys, but additional factors may influence the size of the fat stores in girls.