Thin people can also get fatty liver, which is more dangerous than you think丨National Liver Care Day

With the development of social economy and changes in lifestyle, the incidence of fatty liver in my country is getting higher and higher, and is becoming younger.

The fatty liver we often talk about refers to "non-alcoholic fatty liver disease" in medicine. Since this disease is often closely related to systemic metabolic disorders, the latest guidelines call it "metabolic-related (non-alcoholic) fatty liver disease". For the convenience of reading, we will uniformly refer to it as "fatty liver" in this article.

The "Guidelines for the Prevention and Treatment of Metabolic (Non-alcoholic) Fatty Liver Disease (2024 Edition)" shows that the cumulative prevalence of fatty liver disease in adults in my country has been 29.6% in the past 20 years, replacing viral hepatitis such as hepatitis B to become the number one liver disease in my country.

According to global statistics: 19.2% of patients with fatty liver have a normal body mass index (BMI), that is, "thin people"; 40.8% of patients have a BMI that does not meet the obesity standard; among non-obese or thin patients with fatty liver, 39.0% suffer from fatty liver hepatitis and 29.2% have significant fibrosis.

The metabolic disorder and histological lesions of lean fatty liver are relatively mild, but the long-term prognosis is relatively worse. Compared with fatty liver caused by obesity, lean fatty liver may be more dangerous! This reminds us that the problem of fatty liver in "thin people" or non-obese people needs to be given enough attention by the public.

In the past, fatty liver was once considered a "disease of affluence": if you ate too well, gained weight, and had a big belly, you would get fatty liver.

Generally speaking, fatty liver is a disease that fat people are prone to, which means that obesity can cause metabolic syndrome and ultimately lead to fatty changes in the liver.

But I really want to ask, why do I get fatty liver even though I am so thin?

Here, there is a professional term in medicine called "lean non-alcoholic fatty liver disease", commonly known as "lean fatty liver".

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What is lean fatty liver?

In Asia, lean fatty liver disease refers to fatty liver disease in lean people who are classified as neither overweight nor obese based on their BMI (BMI < 23 kg/m², BMI = weight ÷ height²).

However, due to traditional cognitive bias, people believe that fatty liver disease is caused by overnutrition and excessive fat. This makes it easy for people who are not obese to be ignored when they suffer from fatty liver disease, and thus miss the opportunity for early treatment and intervention.

Why do thin people also get fatty liver?

1. Disorders of fat metabolism

People with a thin body type may develop fatty liver due to fat metabolism disorders caused by lack of exercise, staying up late, drinking, intestinal flora imbalance, genetics and other factors.

Clinically, many thin people not only suffer from fatty liver, but also have symptoms of metabolic syndrome such as high blood sugar, high blood pressure, and high blood lipids. Although these people do not look fat and have slender limbs, in fact, fat has long been quietly deposited in the body, manifesting as abdominal obesity, insulin resistance, and abnormal body fat distribution.

2 Malnutrition

If you are a very thin person, you may also lack protein in your body due to unbalanced nutrition, which will affect the synthesis of apolipoprotein in the liver. In other words, there is a lack of "porters" and triglycerides cannot be transferred out, so they are deposited in the liver in large quantities and induce fatty liver.

Secondly, most thin people like to be vegetarian. Long-term vegetarian diet leads to nutrition that cannot meet the body's needs. Excessive secretion of glucocorticoid hormones causes a large amount of free fatty acids to be released into the blood and liver. The fatty acids in the liver exceed the transport capacity of the liver's apolipoprotein, which is "overloaded". The remaining fatty acids will be deposited in the liver, causing fatty liver.

Fatty liver disease may be more dangerous in thin people than in obese people

Fatty liver is a chronic liver damage that can cause liver damage in patients. If not intervened in time and allowed to develop, fatty liver will progress to liver fibrosis and even cirrhosis. If the patient is not diagnosed and treated effectively at this time, once it progresses to the decompensated stage of cirrhosis, more serious clinical manifestations such as hepatic encephalopathy, ascites, gastrointestinal bleeding, and hepatorenal syndrome will follow, threatening the patient's life and health.

There is evidence that the risk of cardiovascular disease in people who are not overweight with fatty liver is much higher than that in people who are overweight with fatty liver or overweight without fatty liver. This suggests that the long-term cardiovascular disease risk of lean fatty liver cannot be ignored, and that fatty liver in thin people may be more dangerous than fatty liver in fat people.

Do you think fatty liver is painless in the early stages?

Early detection and early intervention can cure fatty liver

Fatty liver has an insidious onset, with no obvious symptoms in the early stages and a relatively slow progression. A small number of patients may have non-specific symptoms such as mild discomfort in the right upper abdomen, dull pain in the liver area or upper abdominal distension and pain, fatigue, etc. Severe fatty liver hepatitis may cause symptoms such as nausea, vomiting, jaundice, and loss of appetite, and some patients will experience symptoms of liver enlargement.

Most patients are diagnosed with fatty liver accidentally during liver function and imaging tests. Even if many patients are diagnosed with fatty liver during physical examinations, they may not feel any pain or itching, and think that it is insignificant and do not pay enough attention to it. However, this is a misunderstanding. Once the disease progresses to cirrhosis or liver cancer, the medical costs and physical pain will be too high.

Therefore, high-risk groups such as those who are overweight, too thin, have abdominal obesity, and chronic alcoholics need to be vigilant. Once they experience loss of appetite, nausea, vomiting, abdominal distension, fatigue, and other discomforts, they need to go to the hospital for a clear diagnosis in time to avoid delaying treatment.

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For people over 40 who have not had a physical examination, especially those with a family history of obesity, fatty liver, diabetes, etc., regular health examinations should be carried out to detect and intervene in diseases early. In addition, simple methods such as measuring waist circumference, abdominal circumference, and waist-to-hip ratio to assess abdominal obesity are also effective means of screening high-risk groups for lean fatty liver in people with normal BMI.

BMI=weight ÷ height².

Recently, the "Dietary Guidelines for Adult Obesity (2024 Edition)" issued by the National Health Commission pointed out that the normal BMI range for healthy adults in my country is 18.5kg/m2 ≤ BMI<24.0kg/m2; adult male waist circumference ≥90cm and adult female waist circumference ≥85cm can be judged as central obesity.

Control your diet and move your legs, and reversing fatty liver is just around the corner

The pathogenesis of lean fatty liver is complex. During the diagnosis and treatment process, attention should be paid to the treatment of liver lesions and the correction of systemic metabolic disorders. Weight loss therapy based on lifestyle intervention is very important in the management of lean fatty liver.

People with "falsely thin" abdominal obesity should reduce weight and waist circumference

Weight loss is more effective in non-obese patients with fatty liver than in obese patients; a 3% to 5% weight loss in non-obese patients can achieve a 50% relief, while a 7% to 10% weight loss is required to achieve the same effect in obese patients.

Balanced nutrition, reasonable diet

For patients with obese fatty liver, it is necessary to control the total calorie intake, ensure a balanced intake of the three major nutrients (sugar, fat, protein), and eat more dietary fiber (vegetables, whole grains, etc.);

For patients with malnutrition-induced fatty liver, the intake of nutrients should not be restricted. They should be given high-protein (eggs, milk, lean meat, etc.) and high-vitamin (vegetables, fruits) foods, and an appropriate amount of fat (nuts, oils, etc.) and carbohydrates (cereals, potatoes, etc.).

Exercise therapy

Do moderate-intensity aerobic exercise 5 days a week for 30 to 60 minutes each time, such as jogging, swimming, ball games, cycling, yoga, aerobics, etc., and combine it with resistance exercise or muscle training 2 to 3 times a week to promote fat burning, such as squats, push-ups, dumbbell lifting and other strength training. Pay attention to the combination of work and rest to avoid excessive fatigue.

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Use medication with caution

For people with lean fatty liver accompanied by metabolic abnormalities, if 6 to 8 weeks of lifestyle intervention is not effective, auxiliary drug treatment can be considered to comprehensively prevent and control risk factors such as abdominal obesity, hypertension, hyperglycemia, and hyperuricemia.

However, it should be noted that many drugs are metabolized by the liver, and improper use of drugs can easily lead to liver damage. Therefore, you need to go to a regular hospital for treatment and use drugs reasonably under the guidance of a doctor. Never believe in folk remedies.

Source: Editorial Department of Liver Doctor

Source: "Liver Doctor" 2025 Issue 1

Author: Zhao Tingting and He Na, the First Affiliated Hospital of Xi'an Medical College

Review expert: Lei Yu, the Second Affiliated Hospital of Chongqing Medical University

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