title: Basal fat oxidation decreases with aging in women.
abstract: The present study tested the hypothesis that a decrease in basal fat oxidation in aging women is related to a loss of fat-free mass. Thirty-two nonsmoking women with a wide range of age (18-73 yr) were characterized for body composition (underwater weight), maximal aerobic capacity, and basal fat oxidation (indirect calorimetry). Results showed that fat oxidation was negatively correlated with age (r2 = 0.17, P = 0.017) but was positively correlated with the fat-free mass (r2 = 0.48, P < 0.0001) and with the level of aerobic fitness (maximal aerobic capacity) (r2 = 0.22, P = 0.007). Unexpectedly, fat oxidation had no relationship with fat mass (r2 = 0.07, P = 0.136). Partial correlation analysis showed that the decline in fat-free mass, and not the age or maximal O2 consumption, was the best single predictor of the decline in basal fat oxidation. These results support the theory that a decrease in fat oxidation with advancing age in healthy women is associated with a decrease in the fat-free mass and not age per se. Interventions that increase or preserve the quantity of fat-free mass (e.g., exercise training) may enhance fat oxidation and thus lessen the age-associated adiposity in women.
authors.affiliation: Division of Endocrinology, Metabolism, and Nutrition, University of Vermont, Burlington 05405.
authors.forename: J
authors.initials: J
authors.lastname: Calles-Escandón
authors.forename: P J
authors.initials: PJ
authors.lastname: Arciero
authors.forename: A W
authors.initials: AW
authors.lastname: Gardner
authors.forename: C
authors.initials: C
authors.lastname: Bauman
authors.forename: E T
authors.initials: ET
authors.lastname: Poehlman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D015308:Anaerobic Threshold / Q000502:physiology; D001481:Basal Metabolism / Q000502:physiology; D001786:Blood Glucose / Q000378:metabolism; D001823:Body Composition / Q000502:physiology*; D002151:Calorimetry; D004562:Electrocardiography; D004734:Energy Metabolism / Q000502:physiology; D005223:Fats / Q000378:metabolism*; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D008875:Middle Aged; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology
chemical_list: D001786:Blood Glucose; D005223:Fats; D007328:Insulin