Systematic Reviews
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Hepatol. Aug 8, 2015; 7(16): 2041-2052
Published online Aug 8, 2015. doi: 10.4254/wjh.v7.i16.2041
Physical activity as a treatment of non-alcoholic fatty liver disease: A systematic review
Maureen Whitsett, Lisa B VanWagner
Maureen Whitsett, Lisa B VanWagner, Department of Medicine, Division of Gastroenterology and Hepatology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States
Author contributions: Whitsett M and VanWagner LB performed the research, wrote the paper, and all authors read and approved the final manuscript.
Supported by The American Association for the Study of Liver Disease (AASLD) Foundation to Dr. VanWagner LB.
Conflict-of-interest statement: The authors have no conflicts of interest to disclose.
Data sharing statement: The tables, references, and technical appendix are available from the corresponding author, Dr. Lisa B. VanWagner, at lvw@northwestern.edu. There is no original data generated by this manuscript.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Lisa B VanWagner, MD, MSc, Department of Medicine, Division of Gastroenterology and Hepatology, Northwestern University Feinberg School of Medicine, Arkes Pavillion 676 N. St. Clair- Suite 1900, Chicago, IL 60611, United States. lvw@northwestern.edu
Telephone: +1-312-9261390 Fax: +1-312-6953999
Received: April 27, 2015
Peer-review started: May 4, 2015
First decision: June 25, 2015
Revised: July 8, 2015
Accepted: July 23, 2015
Article in press: July 27, 2015
Published online: August 8, 2015
Abstract

AIM: To review the effectiveness of exercise as a therapy for nonalcoholic fatty liver disease (NAFLD) and potential benefits in treating insulin resistance and atherosclerosis.

METHODS: Medline (EBSCOhost) and PubMed were searched for English-language randomized controlled trials and prospective cohort studies in human adults aged ≥ 18 which investigated the various effects of exercise alone, a combination of exercise and diet, or exercise and diet coupled with behavioral modification on NAFLD from 2010 to Feburary 2015.

RESULTS: Eighteen of 2298 available studies were chosen for critical review, which included 6925 patients. Nine (50%) studies were randomized controlled trials. Five (27.8%) studies utilized biopsy to examine the effects of physical activity on hepatic histology. The most commonly employed imaging modality to determine change in hepatic steatosis was hydrogen-magnetic resonance spectroscopy. Only two studies examined the effects of low impact physical activity for patients with significant mobility limitations and one compared the efficacy of aerobic and resistance exercise. No studies examined the exact duration of exercise required for hepatic and metabolic improvement in NAFLD.

CONCLUSION: While exercise improved hepatic steatosis and underlying metabolic abnormalities in NAFLD, more studies are needed to define the most beneficial form and duration of exercise treatment.

Keywords: Nonalcoholic fatty liver disease, Non-alcoholic steatohepatitis, Fatty liver, Exercise, Obesity

Core tip: Lifestyle modification through increased physical activity is beneficial in patients with nonalcoholic fatty liver disease (NAFLD). Although weight loss has been shown to produce improvement in biochemical and histological markers of NAFLD, exercise might improve hepatic steatosis and steatohepatitis even in the absence of major weight loss. Cardiovascular and resistance training both seem to benefit patients with NAFLD; further study is needed to determine if one is more effective than the other. A reduction in sedentary time in the absence of increased intense physical activity might also improve NAFLD, although more research is required.