Efficacy of dietary and physical activity intervention in non-alcoholic fatty liver disease: a systematic review

Background: Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide, with prevalence above 30% in many adult populations. Strongly associated with obesity, weight loss through diet and physical activity is the mainstay of its management. Weight loss can be difficult to achieve and maintain however, and uncertainty exists as to which lifestyle changes are most effective. Objective: The aim of this work was to systematically evaluate randomised controlled trials assessing diet, exercise or combination interventions aimed at reducing steatosis or markers of NAFLD activity. Design: Medline, Scopus and Cochrane databases were searched from January 1st 1980 through to July 31st 2016, for intervention trials assessing the effects of diet, weight loss, exercise or any combination thereof, on NAFLD disease markers in human adults. Risk of publication bias and study quality was assessed using the American Dietetic Association Quality Criteria Checklist. Results: From a total of 1710 identified records, 24 articles met the inclusion and exclusion criteria; 6 assessed weight loss using dietary restriction, 10 assessed exercise and 8 were combination interventions. While all of the trials demonstrated significant reduction in steatosis and/or markers of NAFLD activity, combination interventions appear to be the most effective at improving NAFLD. Results suggest that 5-10% weight loss using a modestly hypocaloric diet of 500kcal less per day than calculated energy requirement, in combination with 30-60 minutes exercise on 3-5 days per week should be recommended. Conclusions: We conclude this amount of weight loss is achievable in the trial setting but is challenging in the clinical environment. High intensity, multidisciplinary intervention in specialist clinics is likely to be required in order to manage NAFLD by lifestyle modification alone. This systematic review protocol was registered prospectively at PROSPERO as CRD42016032764.