Long-term effect of exercise on improving fatty liver and cardiovascular risk factors in obese adults: A 1-year follow-up study.

Exercise training can reduce hepatic fat accumulation and cardiovascular risk among patients with non-alcoholic fatty liver disease (NAFLD), but how long these benefits extend beyond the period of active intervention is unclear. Intrahepatic triglyceride (IHTG) content, measured by proton magnetic resonance spectroscopy, and metabolic risk factors among 220 obese people with NAFLD, who were randomly assigned to vigorous/moderate exercise, moderate exercise or no exercise (control), were assessed at 1 year after the 12-month exercise intervention. IHTG content was significantly reduced in the 2 exercise groups compared with the control group over the 12-month active intervention. It was significantly lower (by -2.39%) in the vigorous/moderate exercise group compared with the control group at the 1-year follow-up (95% confidence interval -4.72 to -0.05%; P = .045). Waist circumference and blood pressure remained significantly lower in the vigorous/moderate exercise group and the moderate exercise group compared with the control group at the 1-year follow-up. Visceral adipose fat remained significantly reduced, but with no differences among 3 groups. These findings suggest 12-month exercise intervention induced reductions in hepatic fat accumulation, abdominal obesity and blood pressure for up to 1 year after the active intervention, with some attenuation of the benefits.

Effects of Moderate and Vigorous Exercise on Nonalcoholic Fatty Liver Disease: A Randomized Clinical Trial.

IMPORTANCE: Nonalcoholic fatty liver disease (NAFLD) is a prevalent risk factor for chronic liver disease and cardiovascular disease. OBJECTIVE: To compare the effects of moderate and vigorous exercise on intrahepatic triglyceride content and metabolic risk factors among patients with NAFLD. DESIGN, SETTING, AND PARTICIPANTS: In this randomized clinical trial, participants with central obesity and NAFLD were recruited from community-based screening in Xiamen, China, from December 1, 2011, through December 25, 2013. Data analysis was performed from August 28, 2015, through December 15, 2015. INTERVENTIONS: Participants were randomly assigned to vigorous-moderate exercise (jogging 150 minutes per week at 65%-80% of maximum heart rate for 6 months and brisk walking 150 minutes per week at 45%-55% of maximum heart rate for another 6 months), moderate exercise (brisk walking 150 minutes per week for 12 months), or no exercise. MAIN OUTCOMES AND MEASURES: Primary outcome, change in intrahepatic triglyceride content measured by proton magnetic resonance spectroscopy at 6 and 12 months; secondary outcomes, changes in body weight, waist circumference, body fat, and metabolic risk factors. RESULTS: A total of 220 individuals (mean [SD] age, 53.9 [7.1] years; 149 woman [67.7%]) were randomly assigned to control (n = 74), moderate exercise (n = 73), and vigorous-moderate exercise (n = 73) groups. Of them, 211 (95.9%) completed the 6-month follow-up visit; 208 (94.5%) completed the 12-month follow-up visit. Intrahepatic triglyceride content was reduced by 5.0% (95% CI, -7.2% to 2.8%; P < .001) in the vigorous-moderate exercise group and 4.2% (95% CI, -6.3% to -2.0%; P < .001) in the moderate exercise group compared with the control group at the 6-month assessment. It was reduced by 3.9% (95% CI, -6.0% to -1.7%; P < .001) in the vigorous-moderate exercise group and 3.5% (95% CI, -5.6% to -1.3%; P = .002) in the moderate exercise group compared with the control group at the 12-month assessment. Changes in intrahepatic triglyceride content were not significantly different between vigorous-moderate and moderate exercise at the 6- or 12-month assessment. Body weight, waist circumference, and blood pressure were significantly reduced in the vigorous-moderate exercise group compared with the moderate exercise and control groups at the 6-month assessment and in the vigorous-moderate and moderate exercise groups compared with the control group at the 12-month assessment. In addition, body fat was significantly reduced in the vigorous-moderate exercise group compared with the moderate exercise and control groups at the 12-month assessment. After adjusting for weight loss, the net changes in intrahepatic triglyceride content were diminished and became nonsignificant between the exercise and control groups (except for the moderate exercise group at the 6-month assessment). CONCLUSIONS AND RELEVANCE: Vigorous and moderate exercise were equally effective in reducing intrahepatic triglyceride content; the effect appeared to be largely mediated by weight loss. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01418027.

Serum alanine aminotransferase independently correlates with intrahepatic triglyceride contents in obese subjects.

BACKGROUND AND AIM: Liver enzymes including serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyltransferase (GGT) are well recognized as surrogate makers reflecting non-alcoholic fatty liver disease (NAFLD). However, the associations of serum ALT, AST and GGT with hepatic lipid contents are not well established. The aim of this study was to investigate the relationship between liver enzymes and intrahepatic triglyceride (IHTG) contents, and explore the feasibility in using liver enzymes to reflect accumulation of IHTG in obese subjects. METHODS: A cross-sectional analysis was conducted in 475 obese adults aged 40-65 years. Anthropometric parameters and blood biochemical indexes including liver enzymes, glucose and lipid profiles were measured. The liver triglyceride contents of subjects were determined by (1)H-MRS. RESULTS: Serum ALT, AST and GGT were positively correlated with IHTG contents (p < 0.01). Serum ALT, AST and GGT levels at the highest quartile of IHTG contents were significantly elevated as compared with those in the lowest quartile (p < 0.01). Multivariate linear regression analysis demonstrated that serum ALT, but not AST or GGT was independently associated with IHTG contents. By logistic regression analysis, the odds ratio for higher IHTG contents was increased by 1.464 times/1 SD increase in serum ALT level after adjusting for multiple confounding factors [OR (95% CI) 2.464 (1.584-3.834)]. However, these relationships could not be observed between serum AST or GGT with IHTG contents. CONCLUSIONS: Serum ALT level is independently correlated with the hepatic triglyceride contents in obese subjects and more appropriate to be used as a predictor for the degree of NAFLD rather than AST and GGT.

Irisin is inversely associated with intrahepatic triglyceride contents in obese adults.

BACKGROUND & AIMS: Obesity is closely related to non-alcoholic fatty liver disease (NAFLD), which has become an important public health problem because of its high prevalence and association with metabolic syndromes. Irisin was recently identified as a novel peptide to improve obesity and glucose homeostasis, and considered to be therapeutic for human metabolic diseases. The aim of this study was to examine the association of serum irisin concentration and liver triglyceride contents in obese Chinese adults. METHODS: Serum irisin levels were measured and liver fat contents determined by (1)H MRS in 296 obese adults. Anthropometric parameters and blood biochemical indexes including liver enzymes, glucose, and lipid profiles were detected. The liver triglyceride contents of subjects were measured by (1)H MRS. The protein levels of irisin were determined by quantitative ELISA. RESULTS: We found that serum irisin levels were reduced in obese adults with NAFLD. By dividing the distribution of intrahepatic triglyceride (IHTG) contents into quartiles, serum irisin levels were reduced gradually with the increase of IHTG contents (p<0.01). Higher serum irisin levels were associated with preferable TG levels. Serum ALT and AST concentrations were inversely correlated with serum irisin levels. Multivariate linear regression analysis demonstrated that serum irisin levels were independently associated with liver fat (p<0.01). By logistic regression analysis, the odds ratio for higher IHTG contents was reduced by 12.4% per 1 SD increase in serum irisin concentrations after adjustment for multivariate metabolic factors [OR (95% CI); 0.876 (0.777-0.987)]. CONCLUSIONS: These results demonstrated that serum irisin concentrations were inversely associated with the triglyceride contents in the liver and liver enzymes in obese Chinese adults.