Prediction equations for fat and fat-free body mass in adolescents, based on body circumferences

Abstract

Background: Fat mass (FM) and fat-free body mass (FFB) are important parameters for assessing nutritional status, since they are associated with higher prevalence of excess body fat and malnutrition worldwide.

Aim: To develop prediction equations for fat and fat-free body mass in adolescents using body circumferences.

Subjects and methods: This cross-sectional study included 218 adolescents (10–16 years) with normal weight as defined by body mass index. FM_Pred and FFB_Pred were estimated using stepwise multiple linear regression, considering age and body circumferences. Response variables, FM_BIA and FFB_BIA were estimated using bioelectric impedance analysis (BIA). The accuracy of the prediction equations was evaluated using the coefficient of determination (R²) and Akaike's Information Criterion (AIC).

Results: The best prediction equations for males were FM_Pred = − 7.114 − 0.592(age) − 0.958(wrist)+0.191(hip)+0.295(abdomen); R² = 0.552; AIC = 416.04 and FFB_Pred = − 52.180+1.913(age)+1.954(wrist)+1.635(forearm); R² = 0.869; AIC = 578.24. For females, the best equations were FM_Pred = − 17.580 − 0.678(wrist)+0.221(abdomen)+0.241(hip)+0.202(proximal thigh) − 0.228(calf); R² = 0.838; AIC = 415.36 and FFB_Pred = − 31.066+0.90(age)+1.090(wrist) − 0.139(abdomen)+0.326(hip)+0.632(calf); R² = 0.878; AIC = 512.48.

Conclusion: The equations developed to estimate fat body mass in females and fat-free body mass in both genders had high adjusted coefficients of determination and are therefore preferable to those derived using BIA.

Keywords::

• Body composition
• fat body mass
• fat-free body mass
• prediction equations

Acknowledgements

This study was supported by a National Council for Scientific and Technological Development (Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq) grant (No. 478287-06-2) as part of the research project ‘Risk Factors for Cardiovascular Disease among beneficiaries of the School Feeding Program, Natal, Brazil’.

The authors are also grateful to the Municipal Secretariat of Education of Natal, RN, Brazil and Ana Lúcia Miranda, Marcela Pinheiro Marques and Natália Louise de Araújo Cabral of the Undergraduate Program in Nutrition for their assistance in data collection.

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