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Free-living energy expenditure and behaviour in late infancy
J C Wells1, A Hinds, P S Davies
1Infant and Child Nutrition Group, Dunn Nutrition Unit, Cambridge.
Insights
Infant energy expenditure is influenced by behavior, not just body size. Understanding activity levels is crucial for accurately predicting infant energy needs.
Area of Science:
- Pediatric Nutrition
- Human Physiology
- Behavioral Science
Background:
- Infant energy requirements depend on body size, growth, and physical activity.
- Determinants of energy expenditure on activity in infants are not well understood.
- Investigating the link between free-living energy expenditure and infant behavior is important.
Purpose of the Study:
- To investigate the relationship between free-living energy expenditure and behavior in 9- and 12-month-old infants.
- To determine the factors influencing total energy expenditure (TEE) in infants.
- To assess the predictive accuracy of body size versus behavior on TEE.
Main Methods:
- Total energy expenditure (TEE) estimated using the doubly labeled water method.
- Fat-free mass determined via 18O dilution space.
- Infant behavior assessed through 24-hour activity diaries.
Main Results:
- TEE showed a negative correlation with time spent feeding and time spent upset.
- Fat-free mass explained only 19% of the variation in TEE.
- Fat-free mass combined with two behavioral variables explained 46% of TEE variation.
Conclusions:
- Behavior significantly contributes to total energy expenditure in infants.
- Body size alone is insufficient for accurately predicting individual infant energy requirements.
- Further research into behavioral determinants of infant energy expenditure is warranted.
Objectives:
The energy requirements of infants are determined by body size, growth rate, and physical activity. Little is known of the determinants of energy expended on activity. The relation between free-living energy expenditure and behaviour was investigated in infants aged 9 and 12 months.
Methods:
Total energy expenditure (TEE) was estimated by the doubly labelled water method and fat free mass was estimated from the 18O dilution space. Behaviour was assessed by two 24 hour activity diaries.
Subjects:
Thirty four normal healthy infants.
Results:
TEE was negatively related to the time spent feeding and negatively related to the time spent upset. Body size, represented by fat free mass, accounted for only 19% of the variation in TEE, whereas the combination of fat free mass and two behavioural variables explained 46% of the variation in TEE.
Conclusions:
Behaviour contributed significantly to TEE. The energy requirements of individual subjects in this age group cannot be predicted with accuracy from body size alone.