Nutrition researchers at the University of Illinois Chicago studied 80 people with non-alcoholic fatty liver disease and found that those who followed an alternate-day fasting diet and exercised were able to improve their health.
Publishing their findings in Cell Metabolism, the researchers report that over a three-month period, people who exercised and alternated fasting and feasting days -; eat unrestricted one day and eat 500 calories or less the next -; observed increased insulin sensitivity and decreased liver fat, weight, and ALT, or alanine transaminase enzymes, which are markers of liver disease.
Non-alcoholic fatty liver disease is an accumulation of fat and inflammation in patients who drink little or no alcohol. Approximately 65% of obese adults have the disease, and this condition is strongly linked to the development of insulin resistance and type 2 diabetes. If left unchecked, fatty liver disease can lead to more serious complications, such as cirrhosis or liver failure, but there are limited options for good medications to treat the condition.
Study author Krista Varady called the findings “pretty surprising”.
When we compared the results of our study groups, we saw clearly that the patients who improved the most were in the group that followed the alternate-day fasting diet and exercised five days a week. People who just dieted or just exercised didn’t see the same improvements, which reinforces the importance of these two relatively inexpensive lifestyle modifications in overall health and in fighting chronic diseases like fatty liver disease.”
Krista Varady, professor of nutrition, College of Applied Health Sciences
Clinical trial participants were randomized to one of four groups: an alternate-day fasting group, an aerobic exercise group, a combination group, and a control group in which participants made no changes in their behaviors. Participants in the diet groups tracked their food intake, and participants in the exercise groups used an elliptical machine in Varady’s lab for an hour, five days a week.
Varady said the study didn’t test whether alternate-day fasting was better or worse than other diets when combined with exercise, but she was surprised to see that few participants dropped out of the study.
“Alternate-day fasting and exercise interventions can be difficult for people to maintain, and in previous studies we’ve seen significant dropouts. It was very interesting to see that in this study we had very high adherence to the interventions,” said Varady, who thought that the implementation of the study in onset of the COVID-19 pandemic in 2020 could be a plausible explanation for the variation.
In addition to noting improved metabolic indicators, the study authors also noted that there were no serious safety events during the study -; patients were able to safely maintain their diet and exercise during 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 medications, which can have side effects effects.
In their article, “Effect of alternate-day fasting combined with aerobic exercise on non-alcoholic fatty liver disease: a randomized controlled trial,” which is the first study to examine the effect of intermittent fasting combined with exercise on non-alcoholic fatty liver disease outcomes alcohol consumption, the authors write, “Our findings also indicate that the combined intervention was effective in reducing body weight, fat mass, waist circumference, ALT, fasting insulin, insulin resistance, and increased insulin sensitivity among patients with obesity and NAFLD versus controls”.
Co-authors of the study, funded by the National Institute of Diabetes and Digestive and Kidney Diseases (R01DK119783), include Mark Ezpeleta, Kelsey Gabel, Sofia Cienfuegos, Faiza Kalam, Shuhao Lin, Vasiliki Pavlou, Zhenyuan Song, Jacob M. Haus, Sean Koppe, Shaina J. Alexandria and Lisa Tussing-Humphreys.
University of Illinois Chicago
Speleta, M. and others (2023) Effect of alternate-day fasting combined with aerobic exercise on nonalcoholic fatty liver disease: a randomized controlled trial. Cell Metabolism. doi.org/10.1016/j.cmet.2022.12.001.