There seems to be a consensus among the people: eating too much protein will hurt the kidneys! Protein is obviously one of the most important nutrients for the human body. Without protein, there is no life! Why would such a good thing hurt the kidneys and even the liver? Is it really like this?
As the saying goes: talking about health without considering the nutritional intake is “bullshit”! No matter what nutrition it is, eating too much will have adverse effects on human health! Therefore, although protein is good in many ways, once it is consumed in excess for a long time, it will increase the burden on the kidneys and liver and affect their health! (Note that I am talking about long-term excessive intake!!!)
Why is this so? Let’s start with understanding urea, because understanding the formation process of urea also understands how protein affects the kidneys and liver.
Protein and liver and kidney pressure:
What is urea:
When we draw blood for daily tests, there is an important indicator called: urea. Urea is actually the final product of protein metabolism in the body. It is produced by the liver, dissolved in urine in the kidneys, and finally excreted from the body. Therefore, the metabolic state of human protein can affect the urea value.
Once the following conditions occur in healthy people, the urea value will be higher than normal:
Excessive protein intake:
The protein consumed daily will be used by various tissue cells in the body. After being used by the body tissues, if there is any surplus, then these surplus proteins that are not used by the body cannot be stored in the body and must be decomposed and converted into other substances. Among these other substances, urea is included. The following is the basic process of urea formation:
- Excess protein is converted into amino acids: Because amino acids are the basic units of protein, the first step of protein metabolism is to break down into amino acids;
- Amino acids are deaminated in the liver: Amino acids are mainly composed of amino groups + carbon skeletons. After this process, amino acids become nitrogen-containing parts (including ammonia) and non-nitrogen-containing parts (carbon skeletons, also called α-keto acids);
- The nitrogen-containing part is converted into urea in the liver: The nitrogen-containing part is toxic to the human body (ammonia will be toxic when it accumulates to a certain extent in the human body), and the body needs to hand it over to the liver as soon as possible to convert it into urea;
- Urea enters the kidneys with blood circulation: The urea generated by the liver dissolves in the blood and enters the kidneys through blood circulation;
- The kidneys dissolve urea in urine: The kidneys are like a filter, filtering urea from the blood and dissolving it in urine;
- Excretion: Finally, the urine containing urea will be excreted from the body through the urethra;
The above is the basic process of converting excess protein into urea. Please note: Steps 2 and 3 are both performed in the liver; Step 5 is performed in the kidneys. Therefore, the more excess protein that is consumed and not used by the human body, the more work the liver and kidneys have to do and the heavier the burden (the liver has to produce metabolic waste-urea; the kidneys have to filter urea from the blood and dissolve it into urine)! This is the main reason why excessive protein intake increases the burden on the liver and kidneys!
For healthy people, if they take in excessive amounts of protein for a long time, it will indeed put a burden on the liver and kidneys, and the pressure will be too great. However, there is not enough scientific research data to show that this burden will inevitably cause related diseases. However, if you have weak liver and kidney function or even have a disease, you should avoid taking in too much protein, so as not to overload the liver and kidneys with a high-protein diet!
Well, eat less protein, and the pressure on the liver and kidneys will be less! You think the problem is too simple! Even if the protein intake is not excessive, if the following situations occur, it will still increase the pressure on the liver and kidneys! What are they?
Long-term low-carb diet:
Low-carb diet, in simple terms, means eating very little staple food, or even no staple food. If you eat a low-carb diet for a long time, the body’s internal sugar (carbohydrate) reserves will be severely reduced, and the body needs sugar all the time. In order to maintain normal blood sugar levels, the liver will convert body tissue protein (mainly muscle) into glucose through the process of gluconeogenesis for the body to use.
Please note: When the liver converts body tissue protein into glucose, it will also produce metabolic waste urea (protein must first be converted into amino acids, amino acids must be deaminated, nitrogen-containing parts must be converted into urea, and non-nitrogen-containing parts-carbon skeletons must be converted into glucose).
Therefore, the longer the low-carb diet lasts, the more metabolic waste-urea-produced by body tissue protein (actually protein in food) through gluconeogenesis, and the heavier the burden on the liver and kidneys! Even if the protein you eat does not exceed the standard, the urea produced will increase, because body tissue cells (mainly precious muscle) are also a source of protein!
This is what is called: while losing precious muscle, it also puts a lot of pressure on the liver and kidneys! !
Excessive exercise:
The longer and more intense the exercise (especially strength training or medium-to-high intensity aerobic exercise) lasts, the more sugar the body consumes. Once exercise causes a shortage of sugar in the body, in order to maintain normal blood sugar levels, the liver will also convert body tissue protein (mainly muscle) into glucose through the process of gluconeogenesis for the body to use. Then, metabolic waste urea will also be produced (same as above).
Therefore, excessive exercise will also cause: losing precious muscle while putting a lot of pressure on the liver and kidneys! !
When food energy intake is too low:
When food intake is too low, such as when dieting, the intake of various nutrients will be greatly reduced, especially carbohydrates (staple food) and protein (fish, meat, eggs and milk), and the human body is likely to enter a long-term low-carbon state. Then, I won’t go into too much detail. Because of dieting, it finally appeared: losing precious muscle while putting a lot of pressure on the liver and kidneys, and this time the muscle loss is more (because protein intake is often less)! !
By now, you should know that even if the protein you eat is not excessive, long-term low-carb diet, excessive exercise, and dieting will increase the burden on the liver and kidneys!
Excessive protein intake is only one of the reasons for excessive pressure on the liver and kidneys. Long-term excessive exercise + dieting, this “crazy and fast weight loss mode”, may cause greater danger to the body! In order to learn from it, we need to understand a disease that has serious consequences for the body after a large amount of protein is decomposed: terrible rhabdomyolysis! In severe cases, it may be fatal!
Protein and rhabdomyolysis:
Rhabdomyolysis, in simple terms, is that the muscle protein in the human body is decomposed in large quantities, and a large amount of amino acids decomposed from it flows into the blood, just like we have eaten too much protein in a short period of time. Excessive amino acids, of course, cannot be used in time by our body, and the body needs to convert them into urea in the liver and let the kidneys excrete them through urine, so it puts a great burden on the kidneys in a short period of time. In severe cases, it will cause acute renal failure!
Although this disease is an extreme phenomenon, it is common in China. Here is a real case: News report: In April 2023, Xiao Yi (pseudonym) participated in the “20 catties weight loss in a month” devilish fitness training in the gym to pass the civil service examination. After three days of high-intensity training in the gym, he developed muscle pain, weakness, and tea-colored urine. After diagnosis by the hospital, Xiao Yi suffered from rhabdomyolysis due to frequent weight-bearing in fitness, which caused acute kidney injury, liver function, heart failure, and myocardial damage, and eventually he was admitted to the ICU! ! In the end, the gym paid 31,000 yuan. Why does rhabdomyolysis occur? The main cause is that Xiao Yi performed high-intensity exercise within three days. In high-intensity exercise, the main metabolic mode of the human body is anaerobic metabolism, so the main energy substance is sugar. The higher the intensity of exercise and the longer the duration, the above-mentioned situation will occur: excessive exercise will cause excessive burden on the liver and kidneys! However, is Xiao Yi’s rhabdomyolysis caused entirely by the high-intensity exercise within three days? I don’t think so! High-intensity exercise is just one of the important reasons, or the “trigger”! I guess Xiaoyi will do high-intensity exercise and diet at the same time to achieve the goal of rapid weight loss! ! In other words: high-intensity exercise + diet (probably low-carb), two major body pressures will eventually cause the liver and kidneys to collapse!
In this regard, it is still the old saying I often say: you can’t become a fat man in one breath, and a bunch of annoying fat meat can’t be killed in a short time! Rapid weight loss will destroy your health!
At this point, you should know why it is said that eating too much protein can easily hurt the liver and kidneys. However, we must not be afraid of eating too much protein and significantly reduce protein intake! Because protein is a very important nutrient for the body, there is no life without protein! !
We should always remember: no matter what food you eat, even if it is nutritious, too much or too little will have a negative impact on the body, and moderation is best!
In addition, you must not turn on the “crazy mode” of high-intensity exercise + diet (probably low-carb) in order to lose weight quickly and have a good figure! This mode is ruthlessly destroying your body! !