Regular exercise prevents high-sucrose diet-induced fatty liver via improvement of hepatic lipid metabolism. 
Fatty liver is known as the initial stage in nonalcoholic fatty liver disease.  Epidemiological studies have shown that regular exercise prevents accumulation of hepatic lipids, although the underlying mechanism is unclear.  The purpose of this study was to investigate the effect of exercise on fatty liver associated with hepatic lipid metabolism.  KK/Ta mice (6 weeks old) were divided into sedentary and exercise groups and compared with sedentary Balb/c mice.  All the mice were fed a high-sucrose diet for 12 weeks.  The KK/Ta mice in the exercise group performed a treadmill running exercise at 20 m/min for 30 min (3 times per week).  Twelve weeks of regular exercise suppressed the accumulation of lipid in the liver, along with reduction in the level of lipid in the plasma.  The levels of carnitine palmitoyl transferase II, acyl-coenzyme A dehydrogenase, and trifunctional enzyme, which are rate-limiting enzymes in fatty acid oxidation in the liver, were elevated by exercise.  In addition, the expression of fatty acid synthase, a key lipogenetic enzyme, was reduced by exercise.  Furthermore, regular exercise decreased the expression of heat shock protein 47, a marker of hepatic fibrosis, in the liver.  Our results suggest that regular exercise prevents fatty liver via improvement of hepatic lipid metabolism.