Substrate utilization during short-term fasting in older men and women
Abstract
A 36-h fast had a profound effect on substrate utilization in older women and men. In the postabsorptive state, fat oxidation averaged 52%-55% of REE. After a 36-h fast, fat oxidation increased to 63%-68%, with corresponding decreases in carbohydrate oxidation. The continued reliance on protein oxidation (16%-18% of REE) with fasting may be an important factor in the muscle loss seen in older adults with chronically inadequate food intake and impaired physical activity.
Fields of Study & Subjects
Muscle metabolism and nutrition
Dietary Effects on Health
Genetics
Aging
and Longevity in Model Organisms
Publication details
- Journal / source
- American Journal of Physiology-Endocrinology and Metabolism
- Publisher
- American Physiological Society
- Volume
- 330
- Issue
- 3
- Pages
- E356–E368
- Publication date
- 4 February 2026
- Language
- EN