▎ WuXi AppTec content team editor
Many people may have had a B ultrasound to detect fatty liver during the physical examination, whether it is fat or thin.
In fact, there are many misconceptions about fatty liver.
What causes fatty liver disease? If you have a fatty liver, how can you reverse and destroy the excess fat in the liver? I'll share it with you today.
Who is prone to fatty liver disease? Be careful whether you are fat or thin!
Fatty liver disease is a type of fatty liver disease. Depending on whether there is a cause of long-term excessive alcohol consumption, fatty liver disease is divided into alcoholic fatty liver disease and non-alcoholic fatty liver disease (NAFLD).
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Among them, non-alcoholic fatty liver disease is the most common liver disease in China and Western countries. What we call "fatty liver" in our daily lives is also mainly non-alcoholic.
Non-alcoholic fatty liver disease can not only evolve into cirrhosis and liver cancer, but also is closely related to the increased risk of metabolic syndrome, type 2 diabetes, atherosclerotic cardiovascular disease, and colorectal cancer.
According to the Guidelines for the Prevention and Treatment of Non-alcoholic Fatty Liver Disease (2018 Update), the prevalence of non-alcoholic fatty liver disease in China is more than 25%.
The occurrence and development of NAFLD is related to a variety of factors. There are family genetic factors; there are also problems such as overweight due to high-calorie diet, overnutrition, sedentary and lack of exercise, obesity, insulin resistance, and hyperlipidemia.
What is even more surprising is that the sharp loss of weight and long-term malnutrition are also risk factors for fatty liver.
And for a long time, NAFLD has been considered to be the "exclusive liver disease" of obese people. In fact, people with a normal body mass index (BMI) can also suffer from this disease, which is called lean or non-obese NAFLD.
A study published in The Lancet-Gastroenterology and Hepatology showed that about 40% of people with fatty liver disease worldwide are not obese, and nearly 1/5 of them are still thin.
In 2020, researchers at the University of Tsukuba in Japan analyzed risk factors for lean NAFLD, and the results were published in Hepatology Research.
They found that increased visceral fat, decreased skeletal muscle mass, deterioration in muscle composition (especially in women) and associated abnormal glucose tolerance are important pathological factors for lean NAFLD.
Researchers point out that muscles are an important place for the body's basal metabolism. Reduced muscle mass can lead to difficulties in energy and glucose consumption, so there is excess energy and glucose.
In skeletal muscle with reduced mass or steatosis, glucose that has not had time to be utilized by the muscles is transported to the liver, resulting in NAFLD.
In addition, leptin, muscle suppressors, and metabolic lipopolysaccharidemia can also promote muscle atrophy and increase the likelihood of disease.
For the treatment of non-alcoholic fatty liver disease, no targeted drugs or surgeries have been approved.
To alleviate and reverse fatty liver, it is mainly necessary to change poor lifestyles, focus on healthy eating and exercise lifestyles, prevent abdominal obesity, and lose weight and waist circumference.
With fatty liver, these eating habits need to be changed!
Specifically, fatty liver disease requires dietary adjustments, limiting dietary sugars (especially sugary drinks), and saturated and trans fatty acid intake.
1. Limit sugar in your diet: Eating a lot of sugar can hurt your liver as much as drinking alcohol
In fact, after eating a lot of high-sugar foods, even if you don't drink alcohol, it will lead to fatty liver. This is because high-sugar foods may increase the amount of Klebsiella pneumoniae in the gut, which produces large amounts of alcohol, which damages the liver leading to nonalcoholic fatty liver disease (NAFLD). A study published in the journal Cell Metabolism illustrates this phenomenon.
The team found that about 60 percent of NAFLD patients carried Klebsiella pneumoniae, which produces large or moderate amounts of alcohol, in their guts, while only 6 percent of healthy controls carried these strains. The researchers then fed Klebsiella pneumoniae isolated from the patients to germ-free mice for 3 months.
These mice began developing fatty liver disease after the first month, and the progression of liver disease was similar to that of mice fed with alcohol. And when the team fed the mice antibiotics that killed Klebsiella pneumoniae, the mice reversed.
This shows that Klebsiella pneumoniae can damage the human liver like alcohol, and these bacteria use sugar to produce alcohol, so eating too much sugar (refined rice noodles, pastry bread, biscuits with sugary drinks, etc.) will damage the liver.
However, it is too difficult to change your eating habits in the short term, and it is not okay to eat high-sugar foods for two days once in a while?
This is a sad answer...
2. Don't overeat: Indulge in the fat that comes with one time, and it is difficult to offset it by eating a healthy meal
Many people can't help but eat a high-carb, high-fat, high-salt food when they are stressed...
However, a study published in Scientific Translational Medicine shows that if too much fat and sugar are consumed in the diet, it is even more difficult to remove fats once they accumulate in the liver.
Initially, the scientists gave the mice a 2-week high-fat diet (junk food). Subsequently, the mice were given back to a 6-week regular diet (healthy food) to observe changes in fat accumulation. Unexpectedly, although the phenomenon of fat accumulation has been effectively alleviated, the accumulated fat in liver macrophages can remain undiminished for a long time!
Therefore, if you binge eat unhealthy foods in the short term, even if you return to a healthy diet later, it may be difficult for fat levels to drop to normal values. In the long run, not only can not improve the fatty liver, but also may aggravate the progression of the disease.
How should fatty liver be reversed?
1. In overweight and obese people, the first step is to lose weight
For most people with fatty liver disease, the disease may be related to overweight or obesity, so weight control is a top priority.
The American Association for the Study of Liver Disease NAFLD Practice Guidelines 2017 recommend that for people who already have fatty liver disease:
Losing 3% to 5% of weight within 1 year can improve metabolic syndrome and help reverse simple fatty liver disease;
Weight loss of 7% to 10% can significantly reduce serum aminotransferase levels and improve non-alcoholic steatohepatitis;
A weight loss of more than 10% and maintenance for 1 year can reverse liver fibrosis.
In fact, the guidelines for non-alcoholic fatty liver disease patients weight loss recommendations are slightly different, EASL/EASD/EASO (Europe) NAFLD Management Clinical Practice Guidelines 2018 recommends that patients who are overweight or obese have a target weight loss of 7% to 10%, but regardless of the weight loss target, weight loss should be taken as the top priority.
There are many ways to lose weight, such as eating more vegetables, fruits and whole grains; not eating fatty meats, high-sugar foods, eating lean protein; avoiding sedentary, increasing exercise, etc.
In the process of weight loss, to make the weight loss steady, pay attention to monitoring weight and liver function.
But how many vegetables should I eat?
2. Eat enough vegetables a day
According to the recommendations of MD Anderson Cancer Center, combined with China's Guidelines for the Prevention and Treatment of Nonalcoholic Fatty Liver Disease (2018 Update), vegetables, fruits and whole grains account for two-thirds of daily food.
How much is 2/3? The following numbers are more specific.
The 2016 Dietary Guidelines for Chinese Residents recommend that healthy adults consume 300 to 500g of vegetables per day, of which dark vegetables should account for 1/2.
Another animal study published in the Proceedings of the National Academy of Sciences (PNAS) found that eating only 200g of green leafy vegetables a day can reduce the accumulation of fat in the liver, mainly thanks to its naturally occurring inorganic nitrates.
Therefore, from the overall diet structure, the proportion of polished rice white noodles is not recommended to exceed 1/3, and the daily intake of vegetables is recommended to be 300 to 500g (that is, 6 to 1 kg), of which green leafy vegetables account for 200g.
Eating enough of a pound of vegetables a day seems to be difficult for meat lovers to stick to. It's so busy at work, how do you eat?
You can adjust the diet structure first. Usually an ordinary box lunch can meet the amount of 200 to 300g of vegetables.
However, relatively speaking, it is difficult to ensure the intake of vegetables when eating pasta, such as cold skin, meat sandwich steamed buns, rice noodles, various noodles, wontons and so on.
These foods are typical high-carb low-vegetable staples (also high-sugar foods mentioned earlier), and it is recommended to eat only one meal in three meals.
3. Avoid sitting and exercise in moderation
Some studies have found that the incidence of liver cancer can still be very high by controlling the weight of mice only by diet, without letting them exercise. Therefore, the researchers believe that exercise is also one of the umbrellas that can reduce the occurrence of liver cancer in mice.
Another study published in The Journal of Clinical Endocrinology & Metabolism showed that both high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) can be effective in improving non-alcoholic fatty liver disease.
It is best to do 150-300 minutes of moderate-intensity aerobic exercise per week, or 75-150 minutes of high-intensity exercise, while doing 8-10 sets of impedance training, 2 times a week.
Moreover, China's "Guidelines for the Prevention and Treatment of Non-alcoholic Fatty Liver Disease" also recommends that moderate aerobic exercise be adhered to for 30 minutes a day, 5 times a week; or high-intensity aerobic exercise for 20 minutes a day, 3 times a week, and do 8 to 10 groups of impedance training 2 times a week.
Even if our amount of exercise does not reach the recommended amount of exercise, as long as we do moderate-intensity and above exercise regularly, we can still significantly improve liver fat.
4. You can try a green Mediterranean diet to increase your polyphenol intake
According to a study published in the well-known academic journal Gut (GUT), an improved Mediterranean diet (MED), the Green Mediterranean Diet (Green-MED), is more able to reduce intrahepatic fat and reduce the risk of non-alcoholic fatty liver disease by nearly half compared to other diets.
How does it work?
The first is to limit dietary intake of cholesterol, trans fats, saturated fats, sugars, and salts, increase vegetable intake, and do 45-60 minutes of aerobic training + resistance training 3-4 times a week.
On the basis of these, dietary interventions are carried out.
The Mediterranean diet group and the green Mediterranean diet group have many similarities in terms of diet, including limiting energy intake, 1500-1800 kcal per day for men and 1200-1400 kcal per day for women.
Of the daily intake of fat, 40% is mainly polyunsaturated fats and monounsaturated fats; reduce or avoid red meat and processed meats, and reduce poultry intake.
In addition, although the Mediterranean diet group and the green Mediterranean diet group increased polyphenol intake, the difference was that the Mediterranean diet group increased polyphenols by 440 mg per day, and the main source was walnuts (28 g/day).
The green Mediterranean diet group increased 1240 mg of polyphenols per day, mainly from walnuts (28 g/day), green tea (3-4 cups/day), and aquatic duckweed Wolffia globosa (Mankai strain, 100 g/day, containing higher protein, iron, vitamins, minerals and polyphenols).
After 18 months, the researchers found that the green Mediterranean diet reduced subjects' intrahepatic fat levels by 38.9 percent compared to healthy diets (12.2 percent) and The Mediterranean diet (19.6 percent). At the same time, the prevalence of non-alcoholic fatty liver disease has also been significantly reduced.
The researchers analyzed that the benefits of the green Mediterranean diet may be related to a variety of mechanisms of action of polyphenols, including reducing the production of new fat, increasing fatty acid oxidation and reducing oxidative stress, thereby preventing liver cell damage and reducing liver steatosis.
However, the study also has certain limitations, such as the small proportion of women in the subjects, all of whom are abdominal obese or dyslipidemia, so these results may not be extrapolated to non-abdominal obese or non-dyslipidemia.
But if you have these problems and want to further promote liver health, you may wish to try to increase the proportion of vegetables, fruits, soybeans in the diet, and drink more tea, because these plant foods have a high polyphenol content.
In fact, the causes and mechanisms of non-alcoholic fatty liver disease are not simple, but in the relatively early stages of fatty liver disease, lifestyle changes are the most effective way to reverse the disease.
Insisting on eating less high-sugar and high-fat foods and exercising moderately is a good way to nourish the liver and protect the liver, and at the same time, you can lose weight. Maintaining a healthy weight is the basis for preventing various chronic diseases.
May everyone who loves life have a healthy liver.