Exercise intervention for metabolic abnormalities: reversible repair of non-alcoholic fatty liver disease and systematic optimization of lipid profiles

Clinically, fatty liver is defined as the accumulation of lipids in the liver exceeding 5% of its wet weight. Non-alcoholic fatty liver disease (NAFLD) is mostly caused by obesity, with an incidence rate as high as 75% in obese individuals. The prevalence increases significantly with increasing BMI. Fatty liver caused by obesity does not cause severe damage to liver cells and can be reversibly restored through appropriate exercise combined with dietary control.

Studies have confirmed that exercise does not directly increase the liver's ability to break down fat, but aerobic exercise utilizes fat oxidation for energy, reducing the level of free fatty acids in the blood. This causes fatty acids in the liver to be continuously released into the bloodstream as an energy source, reducing fat in liver cells and alleviating fatty liver. Even if obesity has not completely returned to normal, fatty liver can be completely cured through effective exercise and weight loss.

However, controlling the intensity of exercise is crucial. Excessive intensity not only fails to alleviate fatty liver but may also worsen it. This is because high-intensity exercise causes a surge in fat mobilization, resulting in a large amount of triglycerides entering the bloodstream that cannot be fully utilized and ultimately accumulate in the liver. Furthermore, lactic acid production inhibits the aerobic oxidation of fat. Therefore, only prolonged, low-to-moderate intensity aerobic exercise is the ideal choice.

Hyperlipidemia refers to elevated levels of total cholesterol (TC) or triglycerides (TG) in the blood plasma, and is a major cause of coronary heart disease. Blood lipids originate from two sources: exogenous (dietary intake) and endogenous (synthesized by the liver). Obese patients, especially those with abdominal obesity, are highly susceptible to hyperlipidemia. Daily life should include limiting high-fat foods, increasing dietary fiber intake, and incorporating regular physical exercise.

High-density lipoprotein (HDL), primarily synthesized by the liver, can cross the inner lining of arteries to remove deposited cholesterol, earning it the nickname "vascular cleanser." Lowered HDL levels increase the risk of atherosclerosis. Low-density lipoprotein (LDL), on the other hand, transports cholesterol throughout the body; excessively high levels can burden the cardiovascular system and are known as "bad cholesterol." A balanced diet combined with regular exercise is very helpful in increasing HDL and decreasing LDL.

Exercise significantly improves blood lipid profiles. Long-term, appropriate exercise can reduce the concentrations of total cholesterol (TC), triglycerides (TG), and low-density lipoprotein (LDL), while increasing high-density lipoprotein (HDL) levels. Evaluating the effectiveness of weight loss should not only focus on changes in body shape, but also on improvements in metabolic syndrome.

Exercise for weight loss can also reduce atherosclerotic risk factors in obese individuals. Studies have found that after four weeks of exercise for weight loss, plasma atherosclerotic index (AIP) significantly decreased. This indicates that exercise intervention has a definite effect on reducing the incidence of cardiovascular disease in adulthood. For obese individuals with pre-existing hypertension, moderate-intensity aerobic exercise can not only reduce fat but also significantly lower blood pressure, especially diastolic blood pressure.