Physical activity found beneficial in NAFLD

Regular physical exercise significantly improved measures of nonalcholic fatty liver disease (NAFLD), independently of dietary changes, according to a meta-analysis of randomized clinical trials.

“On the basis of the current findings, physical activity should be recommended not only in combination with dietary changes but also independently as an effective approach to manage NAFLD,” wrote by the University of Geneva. “They proposed that the level of evidence surrounding the specific role of physical activity in the management of NAFLD is now sufficient to be awarded.

Nonalcholic fatty liver disease, “the hepatic manifestation of metabolic syndrome,” affects at least one in four US adults and 15%-35% of individuals in Europe, the Middle East, China, and Japan, the researchers noted. Dietary changes are the cornerstone of NAFLD management, and there is less evidence for how physical exercise affects liver fat content. Therefore, the researchers searched MEDLINE, Embase, and the Cochrane databases from inception through October 2015 to find randomized trials on the impact of physical activity on markers of liver steatosis and liver inflammation in patients diagnosed with NAFLD, obesity, type 2 diabetes, or metabolic syndrome. This approach yielded 28 trials with data from more than 1,600 patients. Only 2 trials were multicenter, 13 required participants to have an NAFLD diagnosis, 4 focused on type 2 diabetes, and most of the rest included sedentary obese patients without requiring a diagnosis of NAFLD.

After researchers accounted for dietary changes, physical activity led to a significant drop in intrahepatic lipid content with a standardized mean difference of -0.69, compared with controls. “Because effect sizes such as standard mean difference [SMD] are difficult to interpret, the translation of such a statistical measure into a clinically relevant notion has been the focus of research for more than a decade. A commonly used interpretation was proposed by who suggested that SMDs of 0.2, 0.5, and 0.8 correspond to small, moderate, and large effect sizes, respectively. With use of this rule of thumb, our results indicate that physical activity exerts a moderate – to- large impact on the reduction of intrahepatic lipid content.”

Exercise reduced liver fat content even more in pediatric patients and in patients who had been specifically diagnosed with NAFLD. Patients with the highest baseline body mass index also seemed to benefit more than patients with lower baseline BMI. Indeed, exercise reduced BMI itself by a weighted mean difference of 0.8, the researchers noted. Exercise intensity did not seem to affect the like hood of benefit. There was a trend toward a greater effect of aerobic over resistance training, and few studies examined the effects of combining both types of exercise.