However, the combined approach did not give significantly added benefit, compared with fasting alone, the researchers report.
Eighty patients with NAFLD were randomized to one of four lifestyle strategies (alternate-day fasting, aerobic exercise, both, or neither) for 3 months.
The primary outcome was change in intrahepatic triglyceride (IHTG) content from baseline to study end, measured by magnetic resonance imaging proton density fat fraction.
The results suggest that “combining intermittent fasting with exercise is effective for reducing hepatic steatosis [fatty liver] in patients with NAFLD but may offer no additional benefit versus fasting alone,” Mark Ezpeleta, PhD, formerly at the University of Illinois, Chicago, and now at the University of Colorado Anschutz Medical Campus, and colleagues conclude.
“Our findings also indicate that the combination intervention was effective for reducing body weight, fat mass, waist circumference, [the liver enzyme alanine transaminase (ALT)], fasting insulin, [and] insulin resistance and increasing insulin sensitivity, among patients with obesity and NAFLD versus controls,” the group reports.
“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 5 days a week,” senior author Krista A. Varady, PhD, professor of nutrition, University of Illinois, said in a press release from the university.
“The people who only dieted or only exercised did not see the same improvements,” she added, “which reinforces the importance of these two relatively inexpensive lifestyle modifications on overall health and on combating chronic diseases like fatty liver disease.”
Moreover, “alternate-day fasting and exercise interventions can be difficult for people to stick to, and in prior studies we have seen significant dropout,” she noted. “It was very interesting to see that in this trial we had very high adherence to the interventions.”
The study was recently published in Cell Metabolism.
An estimated 65% of people with obesity have NAFLD, or fat in the liver that is not the result of excessive alcohol consumption, which is strongly related to the development of insulin resistance and type 2 diabetes, the group writes.
Thiazolidinediones such as pioglitazone reduce hepatic steatosis, but there is mounting concern about the weight-gaining effect of these compounds.
Recent attention has focused on lifestyle interventions to resolve hepatic steatosis, and previous trials showed that alternate-day fasting was effective for certain outcomes in NAFLD, but those studies did not measure changes in IHTG content or include an exercise intervention.
The researchers enrolled 80 adults with obesity and NAFLD and randomized them to one of four groups for 3 months:
- Alternate day fasting group: Participants were instructed to consume 600 kcal at dinner between 5 PM and 8 PM on a fasting day alternating with food as desired on a feasting day.
- Exercise group: A 60-minute moderate-intensity aerobic exercise session 5 times a week.
- Fasting plus exercise group.
- Control group (no intervention).