Independent effects of diet and exercise training on fat oxidation in non-alcoholic fatty liver disease

Ilaria Croci; Nuala M Byrne; Veronique S Chachay; Andrew P Hills; Andrew D Clouston; Trisha M O'Moore-Sullivan; Johannes B Prins; Graeme A Macdonald; Ingrid J Hickman

doi:10.4254/wjh.v8.i27.1137

Independent effects of diet and exercise training on fat oxidation in non-alcoholic fatty liver disease

World J Hepatol. 2016 Sep 28;8(27):1137-1148. doi: 10.4254/wjh.v8.i27.1137.

Authors

Ilaria Croci¹, Nuala M Byrne¹, Veronique S Chachay¹, Andrew P Hills¹, Andrew D Clouston¹, Trisha M O'Moore-Sullivan¹, Johannes B Prins¹, Graeme A Macdonald¹, Ingrid J Hickman¹

Affiliation

¹ Ilaria Croci, Veronique S Chachay, School of Human Movement and Nutrition Sciences, University of Queensland, St. Lucia 4072, Australia.

Abstract

Aim: 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 (Fat_ox) were determined by indirect calorimetry under basal, insulin-stimulated and exercise conditions. Severity of disease and steatosis was determined by liver histology; hepatic Fat_ox was estimated from plasma β-hydroxybutyrate concentrations; cardiorespiratory fitness was expressed as VO_2peak. 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/L vs 0.12 ± 0.04 mmol/L, P = 0.03) but remained unchanged in response to EX (0.10 ± 0.03 mmol/L vs 0.11 ± 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). VO_2peak (P < 0.001) and maximal Fat_ox during 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).

Conclusion: ER and EX lead to specific benefits on fat metabolism of patients with NAFLD. Increased hepatic Fat_ox in response to ER could be one mechanism through which the ER group achieved reduction in steatosis.

Keywords: Beta-hydroxybutyrate; Exercise; Fat and carbohydrate oxidation; Fatty acid oxidation; Fitness; Ketone bodies; Non-alcoholic steatohepatitis; Steatosis.