For Liver Fat, Physical Activity is the Answer

Aerobic exercise, whether it is high intensity or activity that is more moderate, can improve nonalcoholic fatty liver disease (NAFLD), new research shows.

The study, published in the Journal of Clinical Endocrinology and Metabolism, is the first review to determine the effect of aerobic exercise on liver fat by comparing high-intensity interval training (HIIT) to moderate-intensity continuous training (MICT), according to a news release from Western Sydney University.

HIIT workouts are characterized by bouts of high-intensity aerobic exercise alternating with rest periods. MICT workouts are more traditional aerobic exercise training.

The review is also the first to solely include studies that assessed liver fat by “gold standard noninvasive measurement techniques” such as proton magnetic resonance spectroscopy and magnetic resonance imaging.

Researchers from Western Sydney University, the University of Sydney and the University of Queensland considered more than 28,000 studies in their review, but their primary analysis focused on a much smaller group of 19 studies with a total of 745 adult participants.

Their primary analysis showed that both HIIT and MICT resulted in clinically significant liver fat reduction when compared to controls (-2.85% for HIIT versus controls and -3.14% for MICT versus controls).

“It is useful information to know that by training harder in less time with HIIT, you can achieve the same results as MICT, which is ideal for those with a busy lifestyle and little time,” Angelo Sabag, Ph.D., the lead author and postdoctoral research fellow at the NICM Health Research Institute at Western Sydney University, said in the news release.

NAFLD is a predictor of metabolic disorders, closely linked to the development and severity of various diseases such as type 2 diabetes. “Our review demonstrates the importance of regular aerobic exercise as an effective therapy in those at risk, with both HIIT and MICT found to improve liver fat to similar degrees,” Sabag said in the news release.

Another notable finding by Sabag and colleagues was that even if people didn’t exercise enough to meet the recommended physical activity guidelines, they could still achieve clinically significant improvements in liver fat “so long as they exercised regularly above a moderate intensity," Sabag said.

The review builds on previous studies that have shown comparable effects of HIIT to MICT for improving cardiometabolic health including cardiorespiratory fitness and blood pressure.