I am not fat, so fatty liver has nothing to do with me? No! Thin people should also be careful!

Author: Fan Jiangao, Chief Physician of Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine

Chairman of the Fatty Liver Expert Committee of the Chinese Medical Doctor Association and Dean of the Fatty Liver College

Reviewer: Zhang Yu, researcher at Chinese Center for Disease Control and Prevention

With the improvement of living standards and changes in lifestyle, the prevalence of fatty liver among ordinary adults is becoming increasingly higher.

Most cases of fatty liver are asymptomatic and are mostly discovered through health examinations or accidentally through ultrasound or CT scans.

If there is fat deposition in liver cells and it affects more than 5% of liver cells, it can be diagnosed as fatty liver.

Figure 1 Original copyright image, no permission to reprint

Under normal circumstances, there is also fat or lipids in liver cells. Fat is mainly present in the liver stellate cells, also called fat storage cells, which store fat-soluble vitamins, especially vitamin A.

Hepatocytes are mainly liver cells that metabolize sugar, protein, and fat. They do not have fat deposits. When fat synthesis in the liver increases and the synthesized fat is not transported out of the liver, fat will be deposited in the liver, forming fatty liver.

When it comes to fatty liver, everyone thinks it is exclusive to fat people. Indeed, the higher the body mass index, the greater the risk of fatty liver. The longer the obesity lasts and the weight does not steadily decrease, the higher the risk of fatty liver will be over time. The risk of fatty liver will also be much higher if you are obese, have a thick waist circumference, or have parents with fatty liver or diabetes.

There is nothing wrong with the view that fat people are more likely to get fatty liver, but fatty liver is not exclusive to fat people.

1. Can malnutrition cause fatty liver?

Malnutrition means bad. In a broad sense, malnutrition actually includes overweight and abdominal obesity. Obesity is excess calories, which is a bad and unhealthy state. Fatty liver caused by obesity is called non-alcoholic fatty liver disease.

Malnutrition in a narrow sense means insufficient nutrition. Some chronic wasting diseases can cause a sharp drop in weight in a short period of time. When the body is in a low-weight state, the fat synthesized by the liver may not have enough transport vehicles, i.e. apolipoproteins, to transport the fat out, which can also lead to fatty liver and hepatomegaly. We call fatty liver caused by low weight and malnutrition malnutrition fatty liver, which is also relatively common.

2. Can thin people get fatty liver?

Among Asians, the proportion of thin people suffering from fatty liver is much higher than that of Europeans and Americans.

Figure 2 Original copyright image, no permission to reprint

There are several situations in which thin people get fatty liver;

One is a more extreme situation. Some people have too little fat tissue. Once they have excess calories and excess fat, there are too few warehouses to store the fat. The excess fat can only be placed on organs other than adipose tissue. The liver is the first organ to be affected. Therefore, people with too little adipose tissue are prone to fatty liver, even though they are very thin.

In the second situation, the weight is not overweight, but the muscle is too little. Compared with individuals with well-developed muscles or normal individuals, they are actually overweight because the weight from the muscles is decreasing. For the same weight, there is more fat and less muscle, which makes it easy to have insulin resistance, so it is particularly easy to cause fat deposition in the liver.

The third situation is that in the past six months or a year, due to life, work, or other reasons, the weight has increased too fast. In less than six months or a year, the weight has increased by 3%. The sweets and carbohydrates eaten are particularly easy to be converted into fat, and the fat that increases is often fat, which is particularly likely to be stored in the liver. Oriental people are often fat in the liver first, then in the waist, and finally in general.

We have conducted a survey and found that 25% or even 30% of people have a normal body mass index, no increased waist circumference, and no abdominal obesity. It seems that they should not have fatty liver. However, an ultrasound examination revealed that they did have fatty liver. Further investigation revealed that their weight had increased too fast in the past one or two years.

Therefore, the relationship between weight and fatty liver is not absolute, but relative. You cannot judge whether you will get fatty liver based on your weight. It depends on the individual, and you need to conduct examinations to confirm whether you have fatty liver or not.