Researchers from the University of Illinois at Chicago evaluated 80 people with nonalcoholic fatty liver disease and discovered that those who followed an alternate-day fasting diet and exercised were able to improve their health.
The researchers report in Cell Metabolism that over a three-month period, people who exercised and alternated feast and fast days (eating without restriction one day and 500 calories or less the next) had increased insulin sensitivity and decreased liver fat, weight, and ALT, or alanine transaminase enzymes, which are markers for liver disease.
Nonalcoholic fatty liver disease is characterised by the accumulation of fat and inflammation in patients who consume little to no alcohol. The disease affects approximately 65% of obese adults, and it is strongly linked to the development of insulin resistance and Type 2 diabetes. If left untreated, fatty liver disease can progress to more serious complications such as cirrhosis or liver failure, but there are few effective treatment options.
Krista Varady, the study’s author, called the findings “pretty amazing.”
“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 Varady, professor of nutrition at the College of Applied Health Sciences.
“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.”
Participants in the clinical trial were randomly assigned to one of four groups: alternate-day fasting, aerobic exercise, a combined group, or a control group in which no changes were made to their behaviours. Diet group participants tracked their food intake, while exercise group participants used an elliptical machine in Varady’s lab for one hour five days a week.
Varady said the study did not test whether alternate-day fasting was better or worse than other diets when combined with exercise, but she was surprised by how few people dropped out.
“Alternate-day fasting and exercise interventions can be difficult for people to stick to and in prior studies we have seen significant dropout. It was very interesting to see that in this trial we had very high adherence to the interventions,” said Varady, who thought the study’s implementation at the beginning of the COVID-19 pandemic in 2020 could be a plausible explanation for the variation.
The study authors also noted that there were no serious safety events during the trial — the patients were able to safely maintain the diet and exercise for the three-month study, which Varady believes is an indicator that the intervention may be a good option for people with fatty liver disease who want to improve their health without pharmaceuticals, which can have side effects.
The authors write in their paper, “Effect of alternate day fasting combined with aerobic exercise on non-alcoholic fatty liver disease: A randomized controlled trial,” which is the first to look at the effect of intermittent fasting combined with exercise on non-alcoholic fatty liver disease outcomes: “Our findings also indicate that the combination intervention was effective for reducing body weight, fat mass, waist circumference, ALT, fasting insulin, insulin resistance, and increasing insulin sensitivity, among patients with obesity and NAFLD, versus controls.”