The prediction of basal metabolic rate in young adult, severely obese patients using single-frequency bioimpedance analysis

Headnote

Abstract

To evaluate whether bioimpedance analysis (BIA) is a useful tool for predicting basal metabolic rate (BMR), sex, age, height, weight, BMI, and single-frequency BIA variables (resistance index and phase angle) were assessed in 61 young adult non-diabetic obese patients (BMI >35 kg/m^sup 2^). BMR was measured by indirect calorimetry. In both sexes BMR significantly correlated with weight, BMI, and resistance index. Using multiple regression analysis, the following prediction equations were derived: (1) considering individual characteristics: BMR (kcal/day)=780+11.4×weight (+221 for men); (2) including also BIA variables: BMR=-96+8.4xresistance index+8.3xweight+82.5xphase angle. Thus, in young adult, severely obese individuals, BIA variables are significant predictors of BMR.

Key words BMR * Obesity * Body composition * BIA

Introduction

The relationship between basal metabolic rate (BMR) and body weight and body composition has extensively been evaluated in both healthy and ill individuals. Studies aimed mainly to derive prediction equations for BMR on basis of either individual characteristics or body composition variables (e.g., fat-free mass) [1, 2]. This issue is of particular interest since the BMR estimated using these formulas can be employed to assess the energy requirements of individuals when facilities for indirect calorimetry are not available or, strictly speaking, necessary.

Although energy expenditure has been studied in severly obese patients [3-8], the relation between body composition varibles and BMR has never reported in various prediction formulas of BMR. Therefore, the aim of this study was to evaluate whether a simple method for assessing body composition such as bioimpedance analysis (BIA) might be useful for developing prediction equations for BMR in extremely obese patients with no complications.

Patients and methods

Subjects

Sixty-one young adult, nondiabetic, severely obese individuals [body mass index (BMI) >35 kg/m^sup 2^] participated in the study: 34 men [mean age (±SD) 29.4±7.3 years, height 176.1±6.7 cm, weight 140±20 kg, BMI 45.4±6.6 kg/m^sup 2^] and 27 women (mean age 31.6±6.5 years, height 163.0±7.1 cm, weight 121±16 kg, BMI 45.6±6.7 kg/m^sup 2^). Participants were not smokers or light smokers (<10 cigarettes/day). Before enrollment they underwent clinical and routine...