title: Independent effects of diet and exercise training on fat oxidation in non-alcoholic fatty liver disease.
abstract: OBJECTIVE
  To investigate the independent effects of 6-mo of dietary energy restriction or exercise training on whole-body and hepatic fat oxidation of patients with non-alcoholic fatty liver disease (NAFLD).
  
  
  METHODS
  Participants were randomised into either circuit exercise training (EX;n= 13; 3 h/wk without changes in dietary habits), or dietary energy restriction (ER) without changes in structured physical activity (ER;n= 8). Respiratory quotient (RQ) and whole-body fat oxidation rates (Fatox) were determined by indirect calorimetry under basal, insulin-stimulated and exercise conditions. Severity of disease and steatosis was determined by liver histology; hepatic Fatoxwas estimated from plasma β-hydroxybutyrate concentrations; cardiorespiratory fitness was expressed as VO2peak. Complete-case analysis was performed (EX:n= 10; ER:n= 6).
  
  
  RESULTS
  Hepatic steatosis and NAFLD activity score decreased with ER but not with EX. β-hydroxybutyrate concentrations increased significantly in response to ER (0.08 ± 0.02 mmol/Lvs0.12 ± 0.04 mmol/L,P= 0.03) but remained unchanged in response to EX (0.10 ± 0.03 mmol/Lvs0.11 ± 0.07 mmol/L,P= 0.39). Basal RQ decreased (P= 0.05) in response to EX, while this change was not significant after ER (P= 0.38). VO2peak(P< 0.001) and maximal Fatoxduring aerobic exercise (P= 0.03) improved with EX but not with ER (P> 0.05). The increase in β-hydroxybutyrate concentrations was correlated with the reduction in hepatic steatosis (r= -0.56,P= 0.04).
  
  
  CONCLUSIONS
  ER and EX lead to specific benefits on fat metabolism of patients with NAFLD. Increased hepatic Fatoxin response to ER could be one mechanism through which the ER group achieved reduction in steatosis.
authors.affiliation: Ilaria Croci, Veronique S Chachay, School of Human Movement and Nutrition Sciences, University of Queensland, St. Lucia 4072, Australia.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Croci
authors.affiliation: Ilaria Croci, Veronique S Chachay, School of Human Movement and Nutrition Sciences, University of Queensland, St. Lucia 4072, Australia.
authors.forename: Nuala M
authors.initials: NM
authors.lastname: Byrne
authors.affiliation: Ilaria Croci, Veronique S Chachay, School of Human Movement and Nutrition Sciences, University of Queensland, St. Lucia 4072, Australia.
authors.forename: Veronique S
authors.initials: VS
authors.lastname: Chachay
authors.affiliation: Ilaria Croci, Veronique S Chachay, School of Human Movement and Nutrition Sciences, University of Queensland, St. Lucia 4072, Australia.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Hills
authors.affiliation: Ilaria Croci, Veronique S Chachay, School of Human Movement and Nutrition Sciences, University of Queensland, St. Lucia 4072, Australia.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Clouston
authors.affiliation: Ilaria Croci, Veronique S Chachay, School of Human Movement and Nutrition Sciences, University of Queensland, St. Lucia 4072, Australia.
authors.forename: Trisha M
authors.initials: TM
authors.lastname: O'Moore-Sullivan
authors.affiliation: Ilaria Croci, Veronique S Chachay, School of Human Movement and Nutrition Sciences, University of Queensland, St. Lucia 4072, Australia.
authors.forename: Johannes B
authors.initials: JB
authors.lastname: Prins
authors.affiliation: Ilaria Croci, Veronique S Chachay, School of Human Movement and Nutrition Sciences, University of Queensland, St. Lucia 4072, Australia.
authors.forename: Graeme A
authors.initials: GA
authors.lastname: Macdonald
authors.affiliation: Ilaria Croci, Veronique S Chachay, School of Human Movement and Nutrition Sciences, University of Queensland, St. Lucia 4072, Australia.
authors.forename: Ingrid J
authors.initials: IJ
authors.lastname: Hickman
keywords: Beta-hydroxybutyrate; Exercise; Fat and carbohydrate oxidation; Fatty acid oxidation; Fitness; Ketone bodies; Non-alcoholic steatohepatitis; Steatosis