Oral Presentation Australian & New Zealand Obesity Society 2016 Annual Scientific Meeting

The independent effects of dietary energy restriction and circuit exercise training on fat oxidation in patients with NAFLD (#32)

Ilaria Croci 1 2 , Nuala M Byrne 3 4 , Veronique S Chachay 1 2 , Andrew P Hills 5 6 , Andrew D Clouston 7 , Trisha M O'Moore-Sullivan 5 , Johannes B Prins 5 , Graeme A Macdonald 7 8 , Ingrid J Hickman 2 5 9
  1. School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, QLD, Australia
  2. The University of Queensland Diamantina Institute, Translational Research Institute, University of Queensland, Brisbane, QLD, Australia
  3. Bond Institute of Health and Sport, Bond University, Robina, QLD, Australia
  4. Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
  5. Mater Research Institute University of Queensland, University of Queensland, Brisbane, QLD, Australia
  6. School of Health Sciences, University of Tasmania, Lauceston, TAS, Australia
  7. School of Medicine, The University of Queensland, Brisbane, QLD, Australia
  8. Department of Gastroenterology and Translational Research Institute, Princess Alexandra Hospital, Brisbane, QLD, Australia
  9. Department of Nutrition and Dietetics, Princess Alexandra Hospital, Brisbane, QLD, Australia

AIM: To investigate the independent effects of 6-months of energy restriction or exercise training on whole-body and hepatic fat oxidation of patients with NAFLD.

METHODS: Participants were randomised into either circuit exercise training (EX; n=13; 3h/week without changes in dietary habits), or dietary energy restriction 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 Fatox was estimated from plasma b-hydroxybutyrate concentrations; cardiorespiratory fitness (CRF) 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 vs. 0.12±0.04, P=0.03) but remained unchanged in response to EX (0.10±0.03 vs. 0.11±0.07, 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 Fatox 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).

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