Regular exercise training results in clinically meaningful reductions in liver fat in patients with nonalcoholic fatty liver disease, even without resulting weight loss, particularly if it is performed at a moderate intensity for 150 minutes per week, according to a new meta-analysis.
At least 150 minutes of moderate-intensity exercise training each week “remains necessary for clinical improvement, as it is the dose of exercise required to reach the threshold of MRI-measured liver fat reduction that [is a surrogate] for improved histologic outcomes,” lead researcher Jonathan Stine, MD, MSc, FACP, the director of the Fatty Liver Program at Penn State Health, in Hershey, Pa., told Gastroenterology & Endoscopy News.
Dr. Stine and his co-investigators in the Division of Gastroenterology and Hepatology at Penn State University Hershey Medical Center evaluated 14 studies with 551 subjects in their systematic review and meta-analysis (Am J Gastroenterol 2023 Dec 23. doi:10.14309/ajg.0000000000002098). The studies assessed a range of exercise interventions—aerobic (n=10), high-intensity interval training (n=3), resistance training (n=1) and aerobic training plus resistance training (n=2)—that lasted from four to 52 weeks. The mean age of the subjects was 53.3 years (range, 41-62 years); 47% of participants were women; and the mean body mass index was 31.1 kg/m2 (range, 27.1-40 kg/m2).
The investigators found that compared with standard-of-care controls, exercise training subjects had a higher likelihood of achieving at least a 30% relative reduction in MRI-measured liver fat (pooled odds ratio [OR], 3.51; 95% CI, 1.49-8.23; P=0.004). Patients who participated in moderate exercise for at least 150 minutes per week, such as brisk walking or light cycling, had more improvement than patients who spent less time doing exercise of the same intensity (MRI response OR, 3.73; 95% CI, 1.34-10.41; P=0.010).
In addition, they found that patients saw improvements in their liver fat regardless of weight loss. The mean weight loss was 2.8% (range, +1.1% to –4.5%) for exercise intervention.
‘Clinically Meaningful’ Exercise
The investigators concluded that there is a growing body of evidence to support exercise training as a beneficial treatment method for all patients with NAFLD, including those with nonalcoholic steatohepatitis.
They recommended a combination of moderate-intensity aerobic activity and resistance training, emphasizing that exercise should be performed at a minimum of 10 consecutive minutes of moderate exertion per session and that weight-neutral liver fat improvement should be targeted when prescribing exercise for NAFLD patients. (See box.)
Dr. Stine endorsed “lifestyle change for every patient with NAFLD,” which would involve a combination of dietary change and exercise, including in patients who also would benefit from drug treatments. Even if a drug treatment for NAFLD were to become approved by the FDA, “leading a healthy lifestyle will still be a key component of the clinical management of fatty liver disease,” he said.
Cynthia Moylan, MD, MHS, FAASLD, an associate professor of medicine at Duke University, in Durham, N.C., who was not involved with the study, praised its importance as the largest of its kind that assesses the effect of exercise and its intensity and duration on the “amount of liver fat reduction needed to result in potentially clinically meaningful patient outcomes in NAFLD.” She noted that it remains unclear whether these results can be extrapolated to different populations—such as those with more severe obesity—and whether results will vary in patients who undergo supervised versus unsupervised exercise programs. “Closing the gap between the known benefits of physical activity for NAFLD [patients] … and ... patients’ behaviors, understanding and ability to achieve [these benefits] will be one of the most important and impactful future interventions [in combating] this public health crisis.”
—Claire Fisher
Dr. Moylan reported financial relationships with Boehringer Ingelheim, Exact Sciences and GSK. Dr. Stine reported financial relationships with AstraZeneca, Galectin, Grifols, Noom and Novo Nordisk.
This article is from the May 2023 print issue.