ESPE Abstracts

Background: Body mass index not allow to discriminate the proportional composition of the different body compartments: fat mass and fat-free mass

Objective: The aim of this study is to elaborate standardized values of the fat mass index (FMI) and fat-free mass index (FFMI) in healthy adolescents (both sexes) using anthropometric techniques in order to be available as reference standards in daily clinical practice.

Subjects/Methods: Transversal study in 940 healthy Caucasian adolescents (370 males and 570 females), aged 10.1 to 14.9 years. Weight, height, skinfold thickness (biceps, triceps, subscapular and suprailiac) were registered, and body mass index (BMI), percentage of total boy fat, FMI and FFMI, and percentile distribution of FMI and FFMI were calculated.

Results: In males a progressive increase (P<0.05) in the FFMI is observed (10 y: 13,8±0,7 vs. 14 y: 15,6±0,7), and the percentage of total body fat (10 y: 25,4±5,8 vs. 14 y: 22,4±5,9) and FMI (10 y: 4,8±1,4 vs. 14 y: 4,3±1,5) progressively decreased (P<0.05). In contrast, in females the percentage of body fat mass (10 y: 27,4±5,9 vs. 14 y: 29,3±3,5), FMI (10 y: 5,1±1,4 vs. 14 y: 6,2±1,2) and FFMI (10 y: 13,4±0,8 vs. 14 y: 14,7±0,9) progressively increased (P<0.05). Except for the 10 years, FMI was significantly higher (P<0.05) in females with respect to males in all ages. FFMI was significantly higher (P<0.05) in males in all ages. Percentile distributions of FFMI and FMI for healthy adolescents (both sexes) categorized by age are displayed.

Conclusions: Standardized values of fat mass index and fat-free mass index would be a very useful instrument for the diagnosis and analysis of body composition changes during the treatment of childhood obesity.