Development and Validation of a Predictive Equation for Lean Body Mass in Children and Adolescents

Abstract

Background: Lean body mass (LBM) is not easy to measure directly in the field or clinical setting. Equations to predict LBM from simple anthropometric measures, which account for the differing contributions of fat and lean to body weight at different ages and levels of adiposity, would be useful to both human biologists and clinicians.

Aim: To develop and validate equations to predict LBM in children and adolescents across the entire range of the adiposity spectrum.

Subjects and methods: Dual energy X-ray absorptiometry was used to measure LBM in 836 healthy children (437 females) and linear regression was used to develop sex-specific equations to estimate LBM from height, weight, age, body mass index (BMI) for age z-score and population ancestry. Equations were validated using bootstrapping methods and in a local independent sample of 332 children and in national data collected by NHANES.

Results: The mean difference between measured and predicted LBM was − 0.12% (95% limits of agreement − 11.3% to 8.5%) for males and − 0.14% ( − 11.9% to 10.9%) for females. Equations performed equally well across the entire adiposity spectrum, as estimated by BMI z-score. Validation indicated no over-fitting. LBM was predicted within 5% of measured LBM in the validation sample.

Conclusion: The equations estimate LBM accurately from simple anthropometric measures.

Keywords::

• Estimating equation
• body composition
• fat-free mass
• adiposity

Acknowledgements

This study was funded by the National Institute of Child Health and Human Development (NICHD NO1-HD-1-3331), the Clinical and Translational Research Center (5-MO1-RR-000240 and UL1 RR-026314), The Research Institute of the Children's Hospital of Philadelphia and the Children's Hospital of Philadelphia Nutrition Center. Drs Foster and Platt are members of the McGill University Health Centre Research Institute (supported in part by the Fonds de la recherche en santé du Québec (FRSQ)). Dr Foster is supported by the Fonds de la recherche en santé du Québec Junior II Chercheur-Boursier Clinicien award and Dr Platt is supported by the Fonds de la recherche en santé du Québec Senior Chercheur-Boursier award.

Declaration of interest: The authors report no conflict of interests. The authors alone are responsible for the content and writing of the paper.