February 13, 2023 – Exercise can significantly reduce liver fat in patients with nonalcoholic fatty liver disease, one of the common causes of liver disease worldwide, in response to a study. new study published in American Journal of Gastroenterology.
Study participants needed about 150 minutes per week of moderate-intensity physical activity, equivalent to brisk walking, or 75 minutes per week of high-intensity physical activity, equivalent to jogging or cycling.
“Exercise remains a central component of clinical management of NAFLD for all patients with this common disease and should be discussed at every healthcare visit,” says study co-author Jonathan Stine, MD, associate professor of drugs and public health sciences and director of the Fatty Liver Program at Pennsylvania State University-Milton S. Hershey Medical Center.
“As a medical community, we need to do more to support our patients with NAFLD in making healthy lifestyle choices by providing them with a supportive environment rich in exercise-based information and resources,” he says.
NAFLD affects nearly 30% of individuals worldwide. Over time, it will possibly result in liver cirrhosis and cancer. Exercise has been shown to have many advantages for patients with NAFLD, including improvements in liver lipid levels, physical fitness, body composition, vascular biology, and health-related quality of life.
However, it’s unclear whether exercise training achieves a relative reduction in liver fat of 30%, which is taken into account the edge for a clinical difference and improvement in NAFLD.
Stine and colleagues analyzed the evidence for MRI-measured liver reduction in response to exercise training and investigated whether a relative reduction of 30% or more could possibly be achieved at different exercise intensities. They included randomized controlled trials of adults with NAFLD who participated in exercise programs.
In 14 studies involving 551 participants, the typical age was 53 years and the typical body mass index was 31. The studies lasted between 4 and 52 weeks and included various sorts of exercise, equivalent to aerobics, high-intensity interval training, resistance training, and aerobics plus resistance training. The average weight reduction amongst exercise participants was about 2.8%.
In general, those that participated in exercise training were more more likely to achieve a relative reduction in liver fat measured by MRI of 30% or more. Specifically, they were 3.5 times more more likely to achieve the goal than those within the control group.
Among the 551 people, the typical change in absolute liver fat was -6.7% within the 338 individuals who participated within the exercise program in comparison with -0.8% within the 213 people within the control group. In nine studies with 195 people, the typical change in relative liver fat was -24.1% within the exercise program and +7.3% within the control group.
In all 14 studies, an exercise dose of 750 or more metabolic equivalents of task minutes (MET-min) per week produced a major response. This is such as 150 minutes per week of moderate-intensity exercise, equivalent to brisk walking, or 75 minutes per week of vigorous-intensity exercise, equivalent to jogging or cycling.
An exercise dose of 750 or more MET-min per week resulted in a relative reduction in liver fat measured by MRI of 30% or more in 39.3% of participants compared with 25.7% who had lower than 750 MET-min per week. The reduction occurred no matter weight reduction.
“Our work shows a new approach to this important topic,” says Stine. “The goal of exercise in patients with NAFLD should no longer be to lose body weight, but rather to improve their NAFLD, their physical fitness and their overall health.”
There is currently no consensus amongst leading medical societies on the optimal physical activity program for patients with NAFLD, the study authors write. However, most current clinical guidelines recommend at the very least 150 minutes of moderate-intensity aerobic activity per week.
“Exercise brings us many benefits that we don't see. The number on the scale shouldn't be the only thing we pay attention to,” says Dr. Jill Kanaley, professor of nutrition and exercise physiology on the University of Missouri.
Kanaley, who was not involved on this study, has studied exercise in patients with NAFLD. She and her colleagues found that moderate- and high-intensity exercise can reduce risk aspects for NAFLD, even when belly fat or weight doesn't decrease.
“Exercise is good for many systems without causing you to lose weight, it prevents weight gain and is good for your mental health,” she says. “Just getting up and moving is good for you.”