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A Hattori chart analysis of body mass index in infants and children
1Childhood Nutrition Research Centre, Institute of Child Health, London, UK.
Insights
Body mass index (BMI) has limited use for measuring body fatness in children and infants. Variations in fat-free mass (FFM) and fat mass (FM) significantly impact BMI, making it an unreliable indicator of individual adiposity.
Area of Science:
- Paediatric health
- Human body composition
- Nutritional assessment
Background:
- Body mass index (BMI) is a common pediatric measure of fatness.
- Previous analyses of the BMI-fatness relationship in children are insufficient.
Purpose of the Study:
- To examine how variations in fat-free mass (FFM) and fat mass (FM) affect BMI in infants and children.
- To analyze the BMI-fatness relationship using Fomon's reference child data.
Main Methods:
- Measured FFM in 42 infants (12 weeks) and 64 children (8-12 years) using deuterium dilution.
- Calculated FFM index (FFMI) and FM index (FMI).
- Utilized Hattori's body composition chart to analyze the impact of FFM and FM on BMI.
Main Results:
- A single BMI value can represent a wide range of body fat percentages in infants and children.
- Standard deviation of FFMI was over 60% of the standard deviation of FMI.
- Graphic analysis revealed differential effects of lean tissue and fat deposition on BMI across childhood.
Conclusions:
- BMI has limited utility for assessing individual body fatness in infants and children.
- BMI changes over time may be disproportionately influenced by FFM or FM.
- BMI is more useful for tracking short-term nutritional changes and comparing population-level weight.
Background:
Body mass index (BMI) is widely used as an index of fatness in paediatrics, but previous analysis of the BMI-fatness relationship has been insufficient.
Objective:
To consider the effects of variation in fat-free mass (FFM) and fat mass (FM) on BMI in infants, children and Fomon's reference child (Am J Clin Nutr 1982; 35: 1169-1175).
Subjects:
42 infants aged 12 weeks; 64 children aged 8-12 y; Fomon's reference child.
Methods:
FFM was measured by deuterium dilution. FFM index (FFMI) and FM index (FMI) were calculated. The effects of variation in FFM and FM on BMI were explored using Hattori's body composition chart (Am J Hum Biol 1997; 9: 573-578).
Results:
In both infancy and childhood, a given BMI can embrace a wide range of percentage body fat. At both time points, the s.d. of FFMI was > 60% of the s.d. of FMI. Graphic analysis differentiated the effects of lean tissue and fat deposition on BMI with age in the reference child.
Conclusion:
Although valuable for assessing short-term changes in nutritional status in individuals, and for comparing mean relative weight between populations, BMI is of limited use as a measure of body fatness in individuals in both infancy and childhood. The development of BMI with age may be disproportionately due to either FFM and FM at different time points.