Patients with nonalcoholic fatty liver disease may be able to reduce liver fat through regular exercise regardless of resulting weight loss, according to recent results.
Researchers performed a review and meta-analysis of 12 studies on the effect of exercise on changes in liver fat and/or alanine aminotransferase (ALT). The studies included 439 patients. Eleven studies were randomized controlled trials, eight studies compared exercising patients with nonexercising controls, and four compared exercise combined with dietary changes with a group receiving dietary intervention alone. Exercise programs ranged from 2 weeks to 6 months.
Seven studies incorporated aerobic exercise, two used progressive resistance training (PRT) and three combined both methods. The most common frequency of aerobic exercise was 5 days per week (four studies), followed by 3 days per week (two studies). All studies incorporating PRT used regimens of 3 days per week.
Among studies evaluating exercise or exercise with dietary intervention, the pooled effect size (ES) for efficacy on liver fat compared with controls was not statistically significant (ES=–0.05; 95% CI, 0.27 to –0.38), but a pooled ES from six studies comparing an exercising cohort with controls without dietary intervention was statistically significant (ES=–0.37; 95% CI, –0.06 to –0.69). A mean weight loss of less than 0.5 kg occurred in the exercise group across four of these six studies.
No significant pooled ES was established for ALT among all studies incorporating ALT (ES=–0.01; 95% CI, 0.19 to –0.21) and exercise, nor in studies only comparing exercise alone with controls (ES=–0.15; 95% CI, 0.14 to –0.45).
“Individual reports of exercise interventions often have low sample sizes and insufficient power to detect clinically meaningful hepatic benefits,” the researchers wrote. “By pooling current research, we show clear evidence for a benefit of exercise therapy on liver fat but not ALT levels. This benefit is apparent with minimal or no weight loss and at exercise levels below current exercise recommendations for obesity management … The findings confirm a role for exercise as a therapeutic target and suggest that assessment of exercise levels and exercise prescription should be routine in [nonalcoholic fatty liver disease].”