First of all, what kind of fitness do you mean?
If it is running, basketball, skipping rope, swimming, cycling and other fitness that mainly uses aerobic energy and lasts for a long time, then it is healthy for the body. The main part of the body to be exercised: the heart!
If the fitness you are talking about is the kind of strength training that mainly uses anaerobic energy and aims at muscle training, then it is harmful to the body. Because from the perspective of evolution and genes, humans can stand at the top of the food chain, which means that it is the right choice for genes to put talents on the brain. Then, if the brain is developed, muscle growth must be suppressed to balance energy needs. If you force your muscles to grow through acquired training, you are fighting against genes. It is against the natural laws of the human body!
Because big muscles are not what humans should have. From the perspective of survival, endurance and brain power should be beneficial to survival. Big muscle strength, not to mention that more muscles will increase weight, more nutritional support is needed!
If you look at it from the perspective of the body, you need to take in a lot of protein to grow muscles, and protein is metabolized by the kidneys, which will increase the burden on the kidneys!
Therefore, aerobic exercise is good for physical health! Strength training, which is mainly based on muscle training in the gym, is not good for physical health!
However, the following words are the key points, you must read them!
Muscle training is not healthy, why do so many people still exercise?
Because health does not only refer to physical health, but also mental health, so we should say: physical and mental health!
If you are asked to eat boiled vegetables every day, without any additives, light and less oil, your body is very healthy, but can you stick to such a life every day? Are you happy? Is your brain and your soul happy?
So, as long as a body of muscles can satisfy your heart, give you a sense of accomplishment, and nourish your soul, then what is sacrificing a little bit of physical health? As long as it is not excessive and you don’t drink protein powder as water, although it will hurt your body, it is within the tolerance range! While being physically healthy, mentally healthy is also true health!
People nowadays know that staying up late and smoking is bad for the body, why do they do this? Because if you don’t stay up all day you can’t fall asleep, but if you stay up all day you can actually sleep until you wake up naturally.