The intervention for middle-aged and elderly individuals includes a combination of common activities: 15 minutes of walking, 15 minutes of body coordination activities (including limb movements and balance training), 15 minutes of muscle stretching, and 15 minutes of relaxation. Each exercise session lasts for 60 minutes, conducted five days a week. The heart rate during exercise will be adjusted based on monthly fitness assessments, and the daily activity level will be evaluated through logs and fitness trackers.

All participants will be advised not to change their existing lifestyle habits and will only receive health education related to fatty liver throughout the intervention. The educational methods will include large group sessions, individual education, and telephone follow-ups, conducted every two months. Additionally, dietary and exercise assessments will be carried out during the intervention, with dietary intake recorded using a three-day food diary to track daily calorie consumption.

Waist circumference is measured in the morning after fasting. Subjects must stand upright with relaxed abdomen, arms down, and feet together. Use a metric tape at the midpoint between the lower ribs and upper iliac crest (about 1 cm above the navel), wrapped snugly but not compressing the skin. Subjects should breathe normally with a relaxed abdomen, and the measurement is taken at the end of exhalation, avoiding abdominal muscle contraction or breath holding. Repeat twice and record the average, ensuring measurements differ by less than 2 cm, accurate to 0.1 cm.

Subjects must avoid heavy exercise, training, eating, drinking (except water), caffeine, extreme temperatures, and blood pressure-altering meds before measuring. Stop smoking 30 min prior. Relax, empty bladder, rest 5 min. Measure BP in a comfortable room, seated naturally with back straight, palms up. Cuff on bare skin, 1-2 cm above inner elbow, not covering joint, tube aligned with middle finger. Cuff center at heart level. After one measurement, loosen cuff, let subject move arm slightly, then rest 1-2 min before next. Take three measurements, 1 min apart, to 1 mmHg precision.

Using a calibrated hand dynamometer (Brand: CAMRY, Model: EH101).Subjects may stand or sit with their upper limbs naturally hanging at their sides. The palm should face the inner side of the body, with the handle of the dynamometer facing outward.Subjects should grip the dynamometer firmly to measure their grip strength, maintaining a stable posture without swinging the dynamometer back and forth during the measurement.Measure three times and record the maximum value. The dynamometer should be reset to zero before each measurement. Values should be recorded with a precision of 0.1 kg. The measurement can be conducted in the order of right hand followed by left hand.

Using the BIA method, which calculates the proportion of fat and non-fat tissues based on the principle that well-hydrated tissues like muscles and blood vessels conduct electricity well, while fat tissue hardly conducts electricity at all.Measurements should be taken in a fasting state in the morning or more than 2 hours after a meal, with prior notification to the subjects; subjects should avoid vigorous exercise, saunas or baths, excessive alcohol consumption, and the intake of large amounts of water or food (1-2 hours before).Place the body fat analyzer (InBody 770, provided by the research center) on a flat, hard surface. The subject should stand barefoot on the foot electrodes of the body fat analyzer with dry skin, straighten the back and knees, raise the arms horizontally, extend the elbows, and position the arms at a 90° angle from the body with the palms pressed against the electrodes.Precision is to 0.1%.

To measure total body fat, a DEXA densitometer scans subcutaneous fat and body composition. Subjects wear minimal clothing, remove metals, and lie centered on the scanning bed, aligned with the midline. For wider bodies, a half-body scan is possible. The scan includes the head, spine, and one side of the body, with the head 3 cm below the bed's horizontal line. Hands are positioned thumbs up, palms to legs, and arms alongside the body. Nylon straps secure knees and feet. Start the scan from the toolbar, monitor the image for full body display, and reposition if needed. Composition results show fat percentage, and detailed reports are printed from the Reports dialog box.

The FibroScan PRO-S by Echosens measures liver elasticity to assess hardness. Subjects lie supine with the right arm extended. Operators sit on the right, facing the subject and screen, placing the probe between ribs near the liver's right lobe, avoiding the edge. Use A-mode and M-mode to find a 6 cm deep, vascular-structure-free area, keeping the probe perpendicular to the skin. Press until the pressure indicator is green, then press the probe button for 1/10 sec data acquisition. Check the elastogram quality. For disinfection, end the exam, wipe off gel, and clean the probe tip with an alcohol-free disinfectant. Calibrate the probe every 12 months.

Abdominal visceral fat measurement is performed using the SIEMENS 3.0T MRI instrument (Magnetom Prisma, Siemens Healthinners, Erlangen, Germany). During the examination, subjects lie in a supine position and hold their breath while a single-layer cross-sectional MRI scan is taken at the L4-L5 level. After the acquisition, Image J software is used to analyze the area of abdominal visceral fat.

Lab tests include OGTT at 0, 30, 120 min, serum insulin at 0, 30, 120 min, HbA1c, lipids, liver and kidney function. Fasting blood is collected early morning by trained nurses. For OGTT (7-9 a.m.), subjects fast 8-10 hours and drink 75g anhydrous glucose in 300ml water (or 82.5g monohydrate) within 5 min. Blood samples are taken pre-test and at 30, 120 min post-glucose. Avoid tea, coffee, smoking, and heavy exercise. Samples are sent to Fujian Provincial Hospital lab for uniform testing, following standards and accredited.