Density of fat-free body mass: relationship with race, age, and
level of body fatness.
Visser, Marjolein, Dympna Gallagher, Paul Deurenberg, Jack Wang,
Richard N Pierson, Steve B Heymsfield.
Department of Human Nutrition, Wageningen Agricultural University,
Wageningen, the Netherlands, Department of Medicine, Obesity Research
Center, St.Luke's-Roosevelt Hospital, Columbia University College of
Physicians and Surgeons, New York, NY, USA
APStracts 4:0009E, 1997.
The two-compartment body composition method assumes that fat-free body
mass (FFM) has a density of 1.100 kg/L. This study tested the
hypothesis that FFM density is independent of race, age, and body
fatness. Subjects were 703 black and white subjects, ages 20-94
years, with body mass index (BMI) 17-35 kg/m2. Body composition was
assessed using a four-compartment model based on tritium dilution
volume, body density by underwater weighing, bone mineral by dual
-energy x-ray absorptiometry, and body weight. No relationship was
observed between FFM density and race or BMI. A tendency was observed
for a lower FFM density only in older white women. The difference in
percent body fat (_fat) between the four-compartment model and
underwater weighing was <2% for all groups. Race, age, and BMI
explained only 2.3% (women) and 1.4% (men) of the variance in _fat,
while the total body water fraction of FFM explained 77%. In contrast
to current thinking, these results show that the assumption of
constant FFM density is valid in black, elderly, and obese subjects.
Received 2 July 1996; accepted in final form 31 December 1996.
APS Manuscript Number E312-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 19 February 1997