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Low levels of physical activity in 5-year-old children
A D Salbe1, A M Fontvieille, I T Harper
1Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona, USA.
Insights
Pima Indian children are heavier and fatter than white children by age 5, but their energy expenditure is similar. Low physical activity levels in both groups suggest diet, not activity, drives obesity in Pima children.
Area of Science:
- Pediatric obesity research
- Nutritional science
- Human physiology
Background:
- Rising obesity rates in Western societies highlight the need to understand contributing factors.
- Physical inactivity is increasingly recognized as a significant factor in obesity trends.
- Pima Indian children exhibit an extremely high prevalence of obesity.
Purpose of the Study:
- To assess physical activity energy expenditure (AEE) in 5-year-old white and Pima Indian children.
- To compare total energy expenditure (TEE) and resting metabolic rate (RMR) between the two groups.
- To investigate the role of physical activity in the obesity of Pima Indian children.
Main Methods:
- Measured TEE using the doubly labeled water method.
- Measured RMR using indirect calorimetry.
- Calculated AEE and physical activity level (PAL) from TEE and RMR.
Main Results:
- Pima Indian children were significantly heavier and had higher body fat percentage than white children at age 5.
- TEE and RMR were similar between the two groups, even after adjusting for body composition and sex.
- Both groups exhibited PAL values significantly lower than WHO recommendations.
- Calculated physical activity indexes were comparable between white and Pima Indian children.
Conclusions:
- Differences in energy expenditure or AEE do not explain the higher obesity rates in Pima Indian children.
- Excessive food intake is likely a major contributor to obesity in this population.
- Low physical activity levels in both groups are concerning for future obesity prevention.
Abstract:
As the prevalence of obesity in Western societies has increased to disturbing levels, interest in the role of physical inactivity in promoting this trend has increased. We assessed physical activity energy expenditure (AEE) in 127 5-year-old children, 43 of whom were white children and 84 Pima Indian children; the latter group represents a population with an extremely high prevalence of obesity. Total energy expenditure (TEE) and resting metabolic rate (RMR) were measured by the doubly labeled water method and indirect calorimetry, respectively. From these measured values, different indexes of physical activity were calculated, including AEE = TEE-(RMR + 0.1 x TEE) and physical activity level (PAL = TEE/RMR). By the age of 5 years, Pima Indian children were significantly heavier (23.0 +/- 5.3 kg vs 19.1 +/- 2.6 kg) and fatter (30 +/- 7% vs 21 +/- 5% body fat) than white children (p < 0.0001), whereas TEE (5996 +/- 1005 kJ/day vs 5690 +/- 760 kJ/day) and RMR (4431 +/- 625 kJ/day vs 4236 +/- 534 kJ/day) were similar in the 2 groups in both absolute values and after adjustment for fat-free mass, fat mass, and sex. Both white and Pima Indian children had physical activity levels 20% to 30% lower (PAL = 1.35 +/- 0.13) than currently recommended by the World Health Organization (1.7 to 2.0). However, the different calculated indexes of physical activity were comparable in the two racial groups. Differences in TEE or AEE are unlikely to explain the obesity seen in Pima Indian children at a later age, suggesting that excess food intake is likely to play a major role in the cause of obesity in this obesity-prone population. However, both white and Pima Indian children have surprisingly low levels of physical activity, a condition that portends poorly for the prevention of obesity in adulthood.