title: Effect of weight loss on muscle lipid content in morbidly obese subjects.
abstract: The purpose of this study was to test the hypothesis that weight loss results in a reduction in intramuscular lipid (IMCL) content that is concomitant with enhanced insulin action. Muscle biopsies were obtained from morbidly obese individuals [body mass index (BMI) 52.2 +/- 2.5 kg/m(2); n = 6] before and after gastric bypass surgery, an intervention that improves insulin action. With intervention, there was a 47% reduction (P < 0.01) in BMI and a 93% decrease in homeostasis model assessment, or HOMA (7.0 +/- 1.9 vs. 0.5 +/- 0.1). Histochemically determined IMCL content decreased (P < 0.05) by approximately 30%. In relation to fiber type, IMCL was significantly higher in type I vs. type II fibers. In both fiber types, there were reductions in IMCL and trends for muscle atrophy. Despite these two negating factors, the IMCL-to-fiber area ratio still decreased by approximately 44% with weight loss. In conclusion, despite differing initial levels and possible atrophy, weight loss appears to decrease IMCL deposition to a similar relative extent in type I and II muscle fibers. This reduction in intramuscular triglyceride may contribute to enhanced insulin action seen with weight loss.
authors.affiliation: Department of Exercise and Sport Science, East Carolina University, Greenville, North Carolina 27858, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Gray
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Tanner
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Pories
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: MacDonald
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Houmard
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D005260:Female; D006019:Glycolysis; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D050356:Lipid Metabolism; D008297:Male; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D009767:Obesity, Morbid / Q000378:metabolism*; D010084:Oxidation-Reduction; D015431:Weight Loss / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D007328:Insulin