Nonalcoholic fatty liver disease: Combining fasting, cardio may help
- Nonalcoholic fatty liver disease involves the buildup of fat in the liver.
- Fat buildup in the liver is not initially dangerous, but it can put people at risk for other health problems.
- Data from a recent study suggests that combining aerobic exercise, or cardio, with intermittent fasting may improve nonalcoholic fatty liver disease.
The liver is a crucial organ in the body that can influence many areas of health. The buildup of fat in the liver, referred to as nonalcoholic fatty liver disease (NAFLD), is becoming increasingly more common in certain countries.
Researchers are still working to understand the full impact of NAFLD and the best lifestyle choices to reduce the buildup of fat in the liver.
A recent study examined the effectiveness of intermittent fasting and aerobic exercise in reducing fat buildup in the liver. The researchers found that combining these two methods effectively reduced fat levels in the liver.
The study is published in Cell Metabolism
The impact of NAFLD
NAFLD is when fat builds up in the liver. Under this broad term are two subtypes: nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). Nonalcoholic fatty liver is when there is just fat buildup but no damage to the liver. Nonalcoholic steatohepatitis is when there is fat buildup, liver inflammation, and liver damage.
NAFLD is growing more common, including a high prevalence among adults who are obese or who have diabetes.
Dr. Na Li, gastroenterologist and hepatologist, who was not involved in the study, explained to Medical News Today:
“Nonalcoholic fatty liver disease is a medical condition when excessive fat accumulates in the liver. It may cause liver inflammation, scarring, and eventually cirrhosis. This condition has become the most common chronic liver disease and a leading cause for liver transplantation in the United States.”
“People with obesity and type 2 diabetes are particularly at high risk to develop nonalcoholic fatty liver disease.”
— Dr. Na Li
Nonalcoholic fatty liver on its own doesn’t necessarily lead to more severe liver problems, but it can increase someone’s risk for cardiovascular disease and metabolic syndrome.
People with NAFLD can make helpful lifestyle modifications like reaching and maintaining a healthy body weight. However, specialists are still researching the best health option action steps for people with NAFLD.
Combining fasting and exercise for the liver
This particular study was a randomized controlled trial. The study authors conducted the trial over three months and included 80 participants in their analysis. They wanted to look at the effectiveness of different lifestyle interventions in improving fat content in the liver. All participants had obesity and NAFLD.
Study author and intermittent fasting researcher Dr. Krista Varady, explained the basis of the team’s research to MNT:
“We noticed that the main lifestyle therapy for nonalcoholic fatty liver disease (NAFLD) was combining daily calorie restriction with aerobic exercise. We were curious if intermittent fasting combined with aerobic exercise would produce the same reductions in liver fat.”
Intermittent fasting involves only eating during certain time intervals or having specific days with a high amount of calorie restriction. Researchers divided participants into one of four groups to measure improvement in fatty liver.
The first group participated in regular moderate-intensity aerobic exercise. The second group participated in alternate-day fasting, where they only consumed about 600 calories on fast days, and alternated with feast days, where their diet wasn’t restricted.
The third group participated in both an exercise program and intermittent fasting. Finally, the last group was a control group with no interventions.
The combination group demonstrated a variety of improvements, some of which were superior to the other intervention groups.
“We found that liver fat was reduced by 5.5% in the group that participated in both fasting and exercise. This combination group also reduced body weight by 5%, fat mass, waist circumference, and liver enzyme (ALT) levels. We also saw increases in insulin sensitivity in the combination group, indicating better blood sugar control.”
— Dr. Krista Varady
Researchers found that the reduction of liver fat and body weight was similar between the combination group and the group that only participated in intermittent fasting.
Researchers also found that all three intervention groups saw similar improvement in insulin resistance. Thus, the combination intervention could be an option for people with NAFLD but is not necessarily a far-superior method.
Dr. Li said the study “adds to current literature regarding the benefits of weight loss on fatty liver. It is in line with many other studies that calorie restriction is a key component for weight control.”
“Based on this study, alternate day fasting would be adopted as a beneficial strategy by clinicians and patients for weight control and fatty liver treatment,” she told MNT.
The study did have certain limitations that are important to consider.
First, the study included a limited number of participants and ran only for a short time. Over 80% of the participants were female. This and the ethnicity of participants indicate the need for further research that is more diverse.
Second, the combination intervention showed improvements in the liver but not back into a healthy range, which could indicate the need for people with NAFLD to pursue additional interventions. It is also unclear if the interventions would be effective in people with more severe NAFLD.
Because of baseline numerical differences between groups, there was a chance to observe larger average absolute differences in the combination intervention group.
Finally, because of when the study was conducted, the COVID-19 pandemic influenced the exercise interventions and may have led to more variation among participants.
Dr. Varady noted that one of the first steps in continued research would be studies conducted over a longer time frame.
“The study was only 3 months long. I think the next step would be to run longer-term trials in this area (6-12 months long). This will help us determine if these improvements can be sustained over longer periods of time,” she said.
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