Body composition during the first 2 years of life: an updated reference
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Updated: Sep 28, 2026
Assessment of Child Anthropometry in a Large Epidemiologic Study
Published on: February 2, 2017
N F Butte1, J M Hopkinson, W W Wong
1USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA.
Insights
This study established normative body composition references for infants up to two years old. These findings provide crucial data for assessing healthy growth and nutritional status in children.
Area of Science:
- Pediatric Nutrition
- Human Physiology
- Growth and Development
Background:
- Accurate assessment of infant body composition is vital for monitoring growth and nutritional status.
- Existing normative data may not reflect current pediatric populations with mixed feeding practices.
Purpose of the Study:
- To derive normative body composition data for children during the first two years of life.
- To present fat-free mass (FFM) and fat mass (FM) components, growth rates, and conversion constants.
- To establish age- and gender-specific references for pediatric body composition assessment.
Main Methods:
- Prospective study of 76 children from 0.5 to 24 months of age.
- Utilized a multicomponent model including total body water (TBW) via deuterium dilution, total body potassium (TBK) by whole body counting, and bone mineral content (BMC) via DXA.
- Estimated FFM and FM at multiple time points throughout the first two years.
Main Results:
- FFM was higher in boys than girls from 0.5-18 months. Percent FM increased initially then declined, with higher percentages in girls at 6 and 9 months.
- FFM components changed with age, notably increasing protein content and bone mineral percentage, while TBW decreased.
- FFM density and potassium content increased with age, providing further normative insights.
Conclusions:
- This study provides updated normative body composition data for infants and toddlers.
- These references are valuable for assessing the growth and nutritional status of diverse pediatric populations.
- The findings contribute to a better understanding of physiological changes during early childhood development.
Abstract:
Normative body composition during the first 2 y of life was derived from a prospective study of 76 children. We present 1) fat free mass (FFM) and its components, and fat mass (FM), 2) incremental growth rates partitioned into chemical components, and 3) age-specific and gender-specific constants for converting chemical and physical components into FFM for children during the first 2 y of life. A multicomponent model based on measurements of total body water (TBW), total body potassium (TBK) and bone mineral content (BMC) was used to estimate FFM and FM at 0.5, 3, 6, 9, 12, 18, and 24 mo of age. TBW was determined by deuterium dilution, TBK by whole body counting, and BMC by dual energy x-ray absorptiometry. FFM was higher in boys than girls between 0.5-18 mo of age (p < or = 0.05). Percent FM increased on average from 13 to 31% between 0.5 and 3-6 mo, and then gradually declined. Percent FM was significantly higher in girls than in boys at 6 and 9 mo of age (p < or = 0.02). The components of FFM on a percentage basis changed with age (p = 0.001), but not gender. The protein content of FFM increased gradually with age, while TBW declined (p = 0.001). As a percentage of FFM, osseous mineral increased from 2.0 to 3.4% in boys and from 2.1 to 3.3% in girls between 0.5 and 24 mo (p = 0.001). Density and potassium content of FFM increased gradually with age (p = 0.001). These normative body composition data provide an updated reference upon which to assess normal growth and nutritional status of pediatric populations representative of mixed feeding groups during the first 2 y of life.
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