Vigorous- Versus Moderate-intensity Exercise to Reduce Liver Fat in Adults With Obesity and NAFLD

Subjects in the usual care control group will receive health education as the attention control. The program will consist of eight 150-minute bi-weekly sessions covering major health issues relating to general health and NAFLD, to be obtained from publicly accessible resources from the Hong Kong Department of Health. Health education information on non-communicable diseases (e.g., cancers, diabetes, coronary heart diseases, obesity, and mental illness), infectious diseases (e.g., COVID-19), and a healthy lifestyle (e.g., balanced diet, physical activity, good sleep, tobacco use, alcohol cessation, and stress management) will also be distributed to the subjects in the exercise groups through recorded presentation videos and leaflets/pamphlets during the first 16 weeks.

The walking time in each session will be 50 minutes for the moderate-intensity group. The overall weekly exercise volume for the two groups will be the same based on total energy expenditure, as per the WHO's physical activity recommendation (150 minutes of moderate-intensity physical activity weekly is equivalent to 75 minutes of vigorous-intensity physical activity weekly). Five minutes of walking at a normal pace will be included for warm-up and cool-down.

The walking time in each session will be 25 minutes for the vigorous-intensity group. The overall weekly exercise volume for the two groups will be the same based on total energy expenditure, as per the WHO's physical activity recommendation (150 minutes of moderate-intensity physical activity weekly is equivalent to 75 minutes of vigorous-intensity physical activity weekly). Five minutes of walking at a normal pace will be included for warm-up and cool-down.