title: Fasting for 72 h increases intramyocellular lipid content in nondiabetic, physically fit men.
abstract: The purpose of this study was to determine changes in intramyocellular lipid (IMCL) content in the vastus lateralis of nondiabetic, physically fit males over 72 h of fasting. Six men, mean age 35 yr (range 23-55 yr), body mass index 23.7 kg/m2 (21.2-27.4 kg/m2), undertook a water-only fast for 84 h. Vastus lateralis IMCL content was determined using proton magnetic resonance spectroscopy after 12 and 84 h of fasting. Venous blood was sampled at 12-h intervals throughout the fast. IMCL-(CH2)n/water and IMCL-(CH2)n/total creatine ratios increased from 0.00623 +/- 0.00065 to 0.0142 +/- 0.0015 (P = 0.002) and 6.82 +/- 0.87 to 14.96 +/- 1.73 (P = 0.001), respectively. Plasma free fatty acid (FFA), serum triglyceride, and whole blood 3-hydroxybutyrate concentrations increased (P < 0.001, <0.05, <0.03, respectively), whereas plasma glucose and serum insulin concentrations decreased (both P < 0.001) during fasting. In conclusion, 72-h water-only fasting produces a large increase in plasma FFA concentration, a drop in serum insulin concentration, and accumulation of IMCL in the vastus lateralis muscle of nondiabetic, physically fit men.
authors.affiliation: School of Exercise and Sport Science, Faculty of Health Sciences, The University of Sydney, Lidcombe 1825, Australia. stevestannard@ozemail.com.au
authors.forename: S R
authors.initials: SR
authors.lastname: Stannard
authors.forename: M W
authors.initials: MW
authors.lastname: Thompson
authors.forename: K
authors.initials: K
authors.lastname: Fairbairn
authors.forename: B
authors.initials: B
authors.lastname: Huard
authors.forename: T
authors.initials: T
authors.lastname: Sachinwalla
authors.forename: C H
authors.initials: CH
authors.lastname: Thompson
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D005215:Fasting / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood; D007424:Intracellular Fluid / Q000378:metabolism*; D007866:Leg; D050356:Lipid Metabolism; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*; D010809:Physical Fitness / Q000502:physiology*; D012016:Reference Values; D013997:Time Factors; D014280:Triglycerides / Q000097:blood
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D014280:Triglycerides; D020155:3-Hydroxybutyric Acid