A Comparison of the Fat-Free Mass of Young Adults Estimated by Anthropometry, Body Density and Total Body Potassium Content

Abstract

S U M M A R Y1. The fat-free mass (FFM) of ten male and ten female subjects was calculated from measurement of (i) height and weight, (ii) skinfold thickness, (iii) body density, (iv and v) total body potassium by two different methods. All the subjects were apparently healthy and in the medium range of body build and they were mainly young adults.2. The mean FFM of the ten male subjects was similar as calculated by all methods, although comparisons between pairs of methods sometimes produced discrepancies of up to 2 kg.3. Agreement was less good for the females but, with the exception of one of the potassium methods, still reasonable. 4. The potassium content of the FFM as mEq K/kg of FFM, was compared with the direct analysis of Forbes, Gallup & Hursh (1961) on four male cadavers. The agreement was close for the men but the K content of the FFM in women was lower than that for men. This difference is discussed.Key words : fat-free mass, anthropometry, body density, total body potassium content.The assessment of the amount of body fat in individual men and women is now a relatively common procedure. When the fat content of the body is known, the fat-free mass (FFM) may also be determined by simple arithmetical subtraction from the total body weight. Both of these quantities, fat and the FFM, reflect nutritional status and are of considerable medical and physiological interest. The assesssment of obesity and the regulation of desirable weight loss may also require a knowledge of the fat and FFM of the body.Several techniques are now used to estimate body fat and the FFM. These depend usually on extrapolations from measurements (i) by anthropometry of height, weight, skinfold thickness and girths, (ii) of total body water, (iii) of the density of the body, and (iv) of total body potassium. The present paper compares the results of measuring the FFM by five different methods using some of these techniques.Correspondence: Dr J. Womersley, Institute of Physiology, The University, Glasgow G12 8QQ. 469. 470 J. Womersley et al. M E T H O D STen men and ten women, all apparently healthy, acted as subjects; the mean values (and ranges) for age, height and weight were: men, 24 years (17-30), 179 cm (163-191), 68.0 kg (57.0-81.2); women, 28 years (16-54), 160 cm (152-170), 57.0 kg (44.4-68.3). Methodr of estimating FFM Height and weight. Hume & Weyers (1971) measured total body water (TBW) by tritium dilution, and the height and weight, of thirty men and thirty women aged between 33 and 84 years. They established the following regression equations. Men: TBW (litres)=0.297 Wt. (kg) + 0.195 height (cm)-14.013 Women: TBW (litres)=0.184 Wt. (kg) + 0.345 height (em) -35.270We have calculated the FFM of our subjects from measurements of height and weight by using these regressions and the relationship (FFM = 100 TBW/73) established by Rathbun & Pace (1945).Skinfold thickness. Measurement of skinfold thickness was made at four sites on both sides of the body : over the biceps and triceps muscles and at the subscapular and supraili...

Changes in fat-free mass and fat mass in postpartum women: a comparison of body composition models

“…This ®nding challenges the classical value for the potassium content of FFM (68.1 mmol TBK/kg FFM), 21 as being too high for women. Our value is in closer agreement with the values reported by Womersley (59.7 mmol/kg), 35 Sjostrom (62 mmol/kg) 6 and Pierson (56±60 mmol/ kg) 36 for women.…”

Total Body Potassium in Bartter’s Syndrome before and during Treatment with Enalapril

“…A = Before enalapril treatment; B = after 3 months of enalapril treatment; C = after 1 year of enalapril treatment. 1 Reference values for TBK/LBM are 2.26 for women and 2.60 for men [12].…”

“…3 H-48.3 for females (II). Reference values for the index TBK/LBM are derived from Womersley et al [12] who used the same methods as we did for calculating LBM and TBK. Extracellular fluid volume was deter mined as *2Br distribution volume, with corrections applied for Donnan's equilibrium and penetration in erythrocytes [13].…”

Renin and Blood Volume in Chronic Renal Failure: A Comparison with Essential Hypertension

“…LBM was estimated from body weight (BW. in kg) and height (H, in m) using the formulas LBM = 0.407BW + 26.7H-19.2 for men, and LBM =0.252BW + 47.3H-48.3 for women [38], Reference values are: PV, 46-66 ml/kg LBM: BV, 73-103 ml/kg LBM; ECFV, 273-333 ml/kg LBM. Volumes were also expressed per unit H, BW, and body surface area (BSA).…”