title: Exercise and non-alcoholic fatty liver disease: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Exercise is an integral component of lifestyle intervention aimed at weight loss, but an independent benefit of exercise in NAFLD has also been suggested.
  
  
  METHODS
  We aimed to evaluate the efficacy of aerobic exercise and/or progressive resistance training for the modulation of liver fat and alanine aminotransferase (ALT) levels in adults. Relevant databases were searched up to August 2011 for controlled trials, which compared regular exercise vs. a non-exercise control on change in liver fat and/or ALT.
  
  
  RESULTS
  Of the 16,822 studies from the initial search, 12 were included. There was a significant pooled effect size (ES) for the comparison between exercise therapy vs. control (ES=-0.37, 95% CI: -0.06 to -0.69; p=0.02), but only when interventions which compared combined exercise and diet vs. diet-alone and achieved substantial weight loss, were omitted. The benefit of exercise on liver fat occurred with minimal or no weight loss. There was no effect of exercise alone vs. control on ALT (ES=-0.15, 95% CI: 0.14 to -0.45; p=0.32).
  
  
  CONCLUSIONS
  Individual reports of exercise interventions often have low sample sizes and insufficient power to detect clinically meaningful hepatic benefits. By pooling current research, we show clear evidence for a benefit of exercise therapy on liver fat but not ALT levels. This benefit is apparent with minimal or no weight loss and at exercise levels below current exercise recommendations for obesity management. Given the paucity of current treatment options, exercise provides a valid, low-cost therapy for disorders characterised by fatty liver.
authors.affiliation: Discipline of Exercise and Sport Science, University of Sydney, Australia.
authors.forename: Shelley E
authors.initials: SE
authors.lastname: Keating
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Hackett
authors.forename: Jacob
authors.initials: J
authors.lastname: George
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Johnson
mesh_terms: D015444:Exercise / Q000502:physiology*; D005234:Fatty Liver / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D065626:Non-alcoholic Fatty Liver Disease; D009765:Obesity / Q000503:physiopathology / Q000628:therapy; D055070:Resistance Training; D061217:Weight Reduction Programs