Joint Influence of Recreational Physical Activity and Diet Quality on MAFLD: A National Study of Dose-Response and...

Utilizing data from the 2017-2020 National Health and Nutrition Examination Survey (NHANES), this study examined the dose-response relationships and potential synergistic effects of physical activity (PA) and dietary quality (DQ) on the risk of metabolic dysfunction-associated fatty liver disease (MAFLD) among US adults.

A nationally representative sample of 6511 participants was analyzed. PA was quantified as weekly recreational physical activity time, and DQ was assessed using the Healthy Eating Index-2015. Weighted multivariable logistic regression models, adjusted for sociodemographic, metabolic, and behavioral confounders, were used to evaluate associations. Dose-response patterns were examined using smooth curve fitting and segmented regression.

Both higher PA and DQ were independently associated with reduced MAFLD risk (DQ: OR = 0.984, 95% CI = 0.981-0.987; PA: OR = 0.974, 95% CI = 0.969-0.978; both p < 0.0001), with distinct patterns. For PA, each 1-h increase up to 6.776 h/week reduced risk by 9.2% (95% CI: 7.8-10.7%; p < 0.001), with no additional benefit beyond this threshold (p = 0.818). For DQ, each 1-point increase in the Healthy Eating Index-2015 score reduced risk by 0.9% for scores ≤ 50 and by 2.2% for scores > 50. Compared to low PA (≤ 2.5 h/week), moderate (2.5-6.677 h/week) and high PA (> 6.677 h/week) were associated with a 34.1% and 47.7% lower risk, respectively. Moderate and high DQ reduced risk by 15.2% and 38.0% versus low DQ. The combined high-PA/high-DQ group showed the greatest risk reduction (OR = 0.325, 95% CI: 0.278-0.381). In individuals with low DQ, increasing PA from low to high reduced risk by 35.2%-39.3%, whereas improving DQ at low PA levels yielded a more modest reduction (13.4%-29.8%).

PA and DQ were independently associated with a lower MAFLD risk, with PA exhibiting a threshold effect (optimal at ~400 min/week) and DQ demonstrating cumulative benefits at higher scores. Combining high PA and high DQ yields the strongest protective effect, underscoring the importance of integrated lifestyle interventions for MAFLD prevention.