Several studies have shed new light on nonalcoholic fatty liver disease (NAFLD), a shockingly common disorder that is thought to affect 24 percent of adults around the world and about 30 percent of American adults. In a rarer form of NAFLD called nonalcoholic steatohepatitis (NASH), inflammation also occurs in the liver, which can cause scarring and cirrhosis. NAFLD is more common in people with certain disorders, including diabetes and obesity; as many as 75 percent of overweight people may have NAFLD. It's unclear why some people have NASH while others only have NAFLD.
Researchers have now found that fasting every other day could be a way for NAFLD patients to make significant improvements to their health. Recent, unrelated work showed that in a mouse model, fasting promoted the growth of liver cells, so fasting may help NAFLD patients regenerate healthy cells. This latest study, which was reported in Cell Metabolism, followed 80 NAFLD patients over a three-month period.
Volunteers in the trial were randomly placed in one of four groups: the first group fasted on alternate days, eating without any restrictions on one day and limiting caloric intake to fewer than 500 calories the following day; the second group performed aerobic exercise on an elliptical machine for one hour, five days of the week; a third group did the exercise and the alternate-day fasting; and the final control group did not change any of their habits.
In those who fasted on alternate days, insulin sensitivity increased (insulin resistance is very common in the obese), liver fat was reduced, weight decreased, and liver disease markers called alanine transaminase enzymes (ALT), also declined. But fasting combined with exercise had the best impact.
"When we compared the results of our study groups, we saw clearly that the most improved patients were in the group that followed the alternate-day fasting diet and exercised five days a week," said corresponding study author Krista Varady, professor of nutrition at the University of Illinois at Chicago.
"The people who only dieted or only exercised did not see the same improvements, which reinforces the importance of these two relatively inexpensive lifestyle modifications on overall health and on combating chronic diseases like fatty liver disease." Varady said the findings are "pretty amazing."
Interestingly, there were very few participants who dropped out of the study. Varady commented that alternate-day fasting and exercise routines are often challenging for people to stick with, and there have been a significant number of people who left previous studies. But many of the volunteers stayed in the study and stuck to the interventions, which may have be due in part to the onset of the COVID-19 pandemic, Varady added.
There were also no serious safety events in any volunteers throughout the course of the study, and Varady noted that these behavioral changes could be a much safer option for NAFLD patients compared to drugs that may come with side effects.
There were also a number of new insights into how NAFLD progresses to a more severe form, NASH.