Determinants of basal fat oxidation in healthy caucasians.
Nagy, Tim R., Michael I. Goran, Roland L. Weinsier, Michael J. Toth,
Yves Schutz, and Eric T. Poehlman.
Department of Medicine, University of Vermont, Burlington, VT
05405; the Energy Metabolism Research Unit, Department of Nutrition
Sciences, The University of Alabama at Birmingham, Birmingham, AL
35294-3360; the Institute of Physiology, Faculty of Medicine,
University of Lausanne, Lausanne, Switzerland; and the Division of
Gerontology, Department of Medicine, University of Maryland at
Baltimore, Baltimore VA Medical Center, Baltimore, MD 21201
APStracts 3:0020A, 1996.
In a retrospective study, we examined several determinants of basal
fat oxidation in 720 healthy Caucasian volunteers. Adult men (n=427)
and women (n=293) were characterized for resting energy expenditure
and substrate oxidation by indirect calorimetry (after a 12 h
overnight fast); peak oxygen (VO2) consumption from a treadmill test
to exhaustion; body composition by hydrodensitometry; food intake
from a 3-day food diary, and hormonal status by fasting hormone
concentrations. Fat oxidation was negatively correlated with fat mass
in men (r=-0.11; P<0.05) but no statistical relationship was
found in women. In a stepwise multiple regression analysis, fat
oxidation was best predicted by peak VO2 consumption and fat-free
mass in men (model R2=0.14), and by free T4, fat-free mass, and
fasting insulin in women (model R2=0.15). Relative rates of fat
oxidation (fat oxidation adjusted for differences in resting energy
expenditure) were not correlated with fat mass in either gender.
Women showed a lower rate of basal fat oxidation (both absolute and
adjusted) than men. Our results show that fat oxidation is not
greater in individuals with greater fat mass. Furthermore, our
results support a sexual dimorphism in basal rates of fat oxidation.
Received 24 July 1995; accepted in final form 20 December 1995.
APS Manuscript Number A808-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 22 January 96