Let's sort out these conclusions first
Why can't I eat before and after fitness and how long before fitness? This information is very vague. I ate when I was one year old and exercised when I was 20 years old. What I eat before exercise will not affect me. So this "front" needs to be understood according to the actual situation. When your stomach is full of food, most of the blood will be concentrated in your stomach. If this digestion process continues, then exercise again will make more blood flow to the muscular stomach. Enough energy drives digestion, and visceral fat attached to the stomach is not as much as that attached to the intestine, so people are prone to vomiting and stomach problems.
The same is true for fitness.
Therefore, eating before fitness only needs to ensure that the food is digested.
It's even more nonsense not to eat after fitness. However, how can we increase the digestion efficiency of food after fitness? I will never break down 1000 calories after eating 500 calories. Food will only break down faster, not more.
Speaking of exercise fatigue
The human body has an ability called excessive recovery. With enough resistance load and enough food, the body can be strengthened from exercise.
Simply put, moderate exercise, adequate and balanced nutrition, and don't bring any bad habits.
Don't let others say you want to exercise, do millions of push-ups at once. If you haven't finished, you can't have a rest. Don't let others say that you should reduce the amount of exercise appropriately. You have to stay in bed and don't know how to measure it. You always go to extremes and learn to analyze.