title: The effect of short-term fasting on liver and skeletal muscle lipid, glucose, and energy metabolism in healthy women and men.
abstract: Fasting promotes triglyceride (TG) accumulation in lean tissues of some animals, but the effect in humans is unknown. Additionally, fasting lipolysis is sexually dimorphic in humans, suggesting that lean tissue TG accumulation and metabolism may differ between women and men. This study investigated lean tissue TG content and metabolism in women and men during extended fasting. Liver and muscle TG content were measured by magnetic resonance spectroscopy during a 48-h fast in healthy men and women. Whole-body and hepatic carbohydrate, lipid, and energy metabolism were also evaluated using biochemical, calorimetric, and stable isotope tracer techniques. As expected, postabsorptive plasma fatty acids (FAs) were higher in women than in men but increased more rapidly in men with the onset of early starvation. Concurrently, sexual dimorphism was apparent in lean tissue TG accumulation during the fast, occurring in livers of men but in muscles of women. Despite differences in lean tissue TG distribution, men and women had identical fasting responses in whole-body and hepatic glucose and oxidative metabolism. In conclusion, TG accumulated in livers of men but in muscles of women during extended fasting. This sexual dimorphism was related to differential fasting plasma FA concentrations but not to whole body or hepatic utilization of this substrate.
authors.affiliation: Department of Internal Medicine, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX; Department of Internal Medicine, The Advanced Imaging Research Center, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX. Electronic address: jeffrey.browning@utsouthwestern.edu.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Browning
authors.affiliation: Department of Internal Medicine, The Advanced Imaging Research Center, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX.
authors.forename: Jeannie
authors.initials: J
authors.lastname: Baxter
authors.affiliation: Department of Internal Medicine, The Advanced Imaging Research Center, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX.
authors.forename: Santhosh
authors.initials: S
authors.lastname: Satapati
authors.affiliation: Department of Internal Medicine, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX; Department of Internal Medicine, The Advanced Imaging Research Center, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX; Department of Pharmacology, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX. Electronic address: shawn.burgess@utsouthwestern.edu.
authors.forename: Shawn C
authors.initials: SC
authors.lastname: Burgess
mesh_terms: D000328:Adult; D004734:Energy Metabolism / Q000502:physiology*; D005215:Fasting / Q000378:metabolism* / Q000502:physiology*; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D050356:Lipid Metabolism / Q000502:physiology; D008099:Liver / Q000378:metabolism*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D055815:Young Adult
chemical_list: D005947:Glucose