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Energy expenditure and physical activity of obese children: cross-sectional study
C W Yu1, R Y T Sung, R So
1Department of Paediatrics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
Insights
Obese children expend more energy overall but less per body weight, with higher sedentary time. Increasing physical activity is key to reducing childhood obesity.
Area of Science:
- Pediatric Endocrinology
- Human Physiology
- Obesity Research
Background:
- Childhood obesity is a growing public health concern.
- Understanding energy expenditure and physical activity patterns is crucial for intervention strategies.
Purpose of the Study:
- To compare total daily energy expenditure and physical activity patterns in obese and non-obese Hong Kong children.
- To investigate the relationship between body composition and metabolic rate in these groups.
Main Methods:
- A cross-sectional study involving 18 obese and 18 matched non-obese children (aged 6-17) in Hong Kong.
- Energy expenditure and activity patterns were measured over 3 days using heart rate monitoring.
- Body composition was assessed using dual-energy X-ray absorptiometry.
Main Results:
- Obese children had higher absolute total daily energy expenditure, sleep, and sedentary components.
- When normalized for body weight, obese children showed lower total daily energy expenditure.
- Obese children spent significantly more time in sedentary activities and less time in physical activity compared to non-obese peers.
Conclusions:
- Intrinsic metabolic rate differences are unlikely to be the primary cause of obesity.
- Increased sedentary time and reduced physical activity are significant factors in childhood obesity.
- Interventions should focus on increasing physical activity relative to sedentary behaviors to combat childhood obesity.
Objectives:
To investigate the total daily energy expenditure and physical activity pattern of a group of obese and non-obese Hong Kong children.
Design:
Cross-sectional study.
Settings:
University teaching hospital, Hong Kong.
Participants:
Eighteen obese children aged 6 to 17 years and 18 age- and sex-matched non-obese children in the local Hong Kong community.
Main Outcome Measures:
Total daily energy expenditure and physical activity pattern were estimated for 3 days using heart rate monitoring. Body composition was measured by dual-energy X-ray absorptiometry.
Results:
In obese children, both total fat mass and fat-free mass were greater than in non-obese children. Total daily energy expenditure and its sleep and sedentary components were higher in absolute terms (by 42%, 43%, and 126%, respectively) for obese children. When normalised for body weight, the basal metabolic rate was no different between obese and non-obese children, while the total daily energy expenditure of the obese children was significantly lower (by 22%) than that of non-obese children. When normalised for fat-free mass, the basal metabolic rate and the sedentary component of total daily energy expenditure were significantly higher for obese children. Obese children spent 12% less time asleep, but 51% more time in sedentary activity and 30% less time physically active: a ratio of active-to-sedentary waking time of 0.6 for obese children and 1.9 for non-obese children.
Conclusions:
Although the basal metabolic rate may be influenced by body composition, the finding of a normal basal metabolic rate when normalised for body weight suggests that an intrinsic difference of metabolic rate is not a major contributory cause of obesity. The study pointed particularly to the potential benefit of increasing physical exercise time relative to sedentary activities to reduce the prevalence of childhood obesity. Obese and non-obese children had similar basal metabolic rates when adjusted by fat-free mass and fat mass. Obese children spent more time in sedentary activities.