The Role of Exercise for Visceral Fat and the Ectopic Fat “Intramyocellular Lipid”

Abstract

Insulin resistance induced by central obesity is important in the pathogenesis of metabolic syndrome and type 2 diabetes. On the other hand, recent data suggest that ectopic fat accumulation in muscle and liver induces insulin resistance in these organs, independent of obesity. For example, short term dietary therapy decreased intrahepatic lipid levels and improved hepatic glucose metabolism in patients with metabolic disease, while short term aerobic exercise decreased intramyocellular lipid (IMCL) accumulation and improved insulin resistance in skeletal muscle. On the other hand, IMCL accumulation is also observed endurance runners, although their insulin sensitivity is supernormal. This phenomenon is so called “athlete paradox”, and we recently found that difference in fatty acid transporter in skeletal muscle is associated with this phenomenon. In addition, physical inactivity was associated with IMCL accumulation during a 3-day high fat diet. These data suggested that IMCL and muscle insulin resistance are therapeutic target for metabolic disease as well as central obesity and aerobic exercise is important therapeutic option to improve them. We finally addressed a method for aerobic exercise.