This study aims to examine the comparative effectiveness of different exercise frequencies (once-a-week vs. thrice-a-week) for reducing liver fat in centrally obese adults with non-alcoholic fatty liver disease (NAFLD), with weekly exercise volumes aligned with the World Health Organization's physical activity recommendations.

This study is a three-arm randomized controlled trial. Participants will be randomly allocated to the once-a-week exercise group, thrice-a-week exercise group, or usual care control group. The exercise intervention groups will receive once-a-week or thrice-a-week exercise (with matched weekly exercise volumes). The usual care control group will receive general health education. All interventions will last for 4 months. Outcome measures will be examined at baseline, 4 months (post-intervention), and 10 months (6-month follow-up).

Inclusion Criteria:

1. Cantonese, Mandarin, or English speaking Chinese;
2. Aged 18-69;
3. Male or female;
4. Centrally obese according to the Asian-specific cut-off (waist circumference ≥90 cm for males; ≥80 cm for females) and with BMI ≥23;
5. With NAFLD (defined as >5% intrahepatic triglycerides assessed by 1H-MRS);
6. Willing to participate in exercise training to improve NAFLD.

Exclusion Criteria:

1. Regular exercise training (>3 sessions of >60 min of moderate-intensity exercise training weekly) in the past 6 months;
2. Medical history of cardiovascular disease, chronic pulmonary or kidney disease, heart failure, cancer, and/or liver disease except NAFLD;
3. Somatic conditions that limit exercise participation (e.g., limb loss);
4. Impaired mobility due to chronic disease (e.g., chronic arthritis/osteoarthritis, neurological, musculoskeletal, and autoimmune diseases);
5. Daily smoking habit;
6. Excess alcohol consumption (daily ≥20 g of alcohol for men and ≥10 g for women) in the past 1 year;
7. Consumption of certain drugs (e.g., tamoxifen and estrogen) known to be secondary causes of steatosis;
8. Surgery, therapy, or medication for obesity or weight loss in the past 6 months (e.g., gastric bypass, gastric band, sleeve gastrectomy, gastric reduction duodenal switch, or dietitian-prescribed dietary program);
9. Physical changes that considerably affect body composition and weight (e.g., anorexia nervosa, bulimia nervosa, prolonged gastrointestinal and digestive disorders) during the study period.

The data of individual participants that underlie the results reported in this trial, after de-identification including text, tables, figures, and appendices, as well as study protocol and statistical analysis plan, will be shared after 3 months of study publication. Data will be shared with researchers who provide a methodologically sound proposal for academic purposes. Proposals should be directed to pmsiu@hku.hk to gain access and for data request, a data-access agreement needs to be signed.

Beginning 3 months and ending 3 years following the publication of the article.

Data will be shared with researchers who provide a methodologically sound proposal for academic purposes. Proposals should be directed to pmsiu@hku.hk to gain access and for data request, a data-access agreement needs to be signed.