People with NAFLD who exercise are 3.5 times more likely to achieve liver fat reduction
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Physically active patients with nonalcoholic fatty liver disease were more likely to achieve at least a 30% reduction in MRI-measured liver fat, according to research in The American Journal of Gastroenterology.
“In the absence of a regulatory agency-approved drug treatment or a cure, lifestyle modification with dietary change and increased exercise is recommended for all patients with NAFLD,” Jonathan G. Stine, MD, MSc, director of the fatty liver program and associate professor of medicine and public health sciences at Penn State Health, told Healio.
“With that said, there are many key unanswered questions about how to best prescribe exercise as medicine to our patients with NAFLD, including whether the liver-specific benefit of exercise can be seen without body weight loss and if found, what dose of exercise is required in order to achieve clinically meaningful benefit.”
In a systematic review and meta-analysis, Stine and colleagues examined the association between exercise training (defined as a type of physical activity which is planned, structured, repetitive and intended to improve or maintain physical fitness) and reduction in MRI-measured liver fat (30% relative reduction). They also compared the impact of different exercise doses on absolute and relative change in liver fat.
The final analysis included 14 studies, comprised of 551 patients with NAFLD (mean age, 53.3 years; 47% women; mean BMI 31.3 kg/m2).
Seven studies (152 patients) were used in the analysis of the primary outcome. The pooled rate of at least a 30% relative reduction in MRI-measured liver fat was 34% among patients in the exercise training group vs. 13% among patients in the control group. Further, exercise training correlated with an increased likelihood of achieving this reduction (pooled OR = 3.51; 95% CI, 1.49-8.23).
In an analysis of 14 studies for the secondary outcomes, the mean change in absolute liver fat was –6.7% and –0.8% for exercise and control groups, respectively (pooled mean difference = –5.8%; 95% CI, –8.1 to –3.6). Nine studies were analyzed to determine the mean relative change in liver fat of –24.1% vs. 7.3% (–26.4%; 95% CI, –47.2 to –5.5). Further, an exercise dose of at least 750 metabolic equivalents of task minutes per week, such as 150 minutes of brisk walking, led to a greater reduction in liver fat (OR = 3.73; 95% CI, 1.34-10.41) compared with lesser doses of exercise.
Researchers also noted treatment response was independent of “clinically significant” body weight loss of 5% or more.
“Our work highlights a novel way to approach this important topic by suggesting that the goal of exercise training in patients with NAFLD should no longer be to lose body weight, but rather to improve their NAFLD, physical fitness and overall health,” Stine said.
However, he noted further research is needed to investigate mechanisms underlying the benefit of exercise, understand and develop the best tools to effectively screen and assess a patient for NAFLD prior to starting an exercise program, and determine optimal exercise prescriptions for potential improvement of other health outcomes.
“We also need to determine how to best incorporate collaboration with an exercise specialist into the routine clinical care of patients with NAFLD,” Stine said.
Perspective
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Jamile' Wakim-Fleming, MD
NAFLD affects about 30% of the general population, including children. It can lead to cirrhosis and related complications, and is often associated with obesity, diabetes, high blood pressure, cardiovascular disease and death.
There are currently no FDA-approved medications to treat NAFLD, thus the recommendations for its management emphasize weight loss of 5% and 10% to reduce fat and fibrosis, respectively, from the liver.
However, weight loss is hard to achieve, and obesity rates continue to rise. Medications and surgical interventions are often necessary, but they are not recommended for everyone. Additionally, medications to remove fat from the liver are not available yet.
Patients can feel discouraged when obesity affects their liver health and overall health — particularly if weight loss becomes a lifelong challenge.
The study by Stine and colleagues shows that brisk walking for 150 minutes a week can significantly decrease fat in the liver regardless of weight loss. This is an important finding that should change how we approach the discussion of fatty liver management with our patients.
Emphasizing the walk, not the weight, may be a good start to help improve the epidemic of obesity and fatty liver disease.
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