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Published on: February 2, 2017
Composition of the fat-free mass in obese and nonobese children: matched case-control analyses
D Haroun1, J C K Wells, J E Williams
1MRC Childhood Nutrition Research Centre, Institute of Child Health, London, UK.
Insights
Obese children have different body composition, with higher hydration and lower fat-free mass density. These factors are crucial for accurate body composition analysis in childhood obesity treatment.
Area of Science:
- Pediatric endocrinology
- Human physiology
- Body composition analysis
Background:
- Standard body composition techniques assume constant fat-free mass (FFM) properties.
- Childhood obesity may alter FFM composition, but this remains under-investigated.
Purpose of the Study:
- To compare FFM composition between obese and nonobese children.
- To highlight the impact of obesity on FFM characteristics in pediatric populations.
Main Methods:
- Observational matched case-control study involving 28 obese and 22 nonobese children (aged 7-14 years).
- Measurements included weight, height, total body water, and body volume.
- Body composition was analyzed using three- and four-component models.
Main Results:
- Obese children exhibited significantly greater FFM hydration (P<0.05 to P<0.01).
- Obese children showed reduced FFM density (P=0.057 to P<0.002).
- FFM mineralization was increased in obese children, though not significantly.
Conclusions:
- Altered FFM hydration and density in obese children necessitate adjustments for accurate body composition assessment.
- Multicomponent models are recommended over two-component models for pediatric obesity.
- The four-component model best accounts for hydration and mineralization variations in childhood obesity.
Objective:
Most body composition techniques assume constant properties of the fat-free mass (FFM), such as hydration, density and mineralisation. Previous studies suggested that FFM composition may change in childhood obesity; however, this issue has not been investigated in detail.
Aim:
To compare FFM composition in obese and nonobese children.
Design:
Observational matched case-control analyses.
Subjects:
A total of 28 obese children (13 boys, 15 girls) and 22 nonobese children (10 boys, 12 girls) aged 7-14 y. Obesity was defined as body mass index centile >95.
Methods:
Measurements were made of weight, height, total body water, and body volume. Bone mineral content was estimated in a subsample. Body composition was calculated using three- and four-component models.
Results:
According to the three-component model (n=22 matched pairs), obese children had greater hydration (P<0.05), and reduced density (P=0.057) of FFM. According to the four component model (n=11 pairs), obese children had greater hydration (P<0.01) and reduced density (P<0.002) of FFM. The mineralisation of FFM was increased, but not significantly so.
Conclusion:
The greater hydration and reduced density of FFM of obese children should be taken into account if body composition is to be measured with optimum accuracy during treatment programmes. These differences may be addressed by using multicomponent rather than two-component models of body composition. Although the greater mineralisation of FFM in obese children was not significant in the present study, the four-component model is best able to address the combined differences in hydration and mineralisation that occur in childhood obesity.
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