First, if you want to gain muscle, then add some carbohydrates and protein half an hour before fitness. Hypoglycemia is easy after exercise, so add some carbohydrates before fitness.
Second, if you want to lose weight, try not to eat or eat less for two or three hours before exercise.
In terms of time, exercise before meals is the best, and the most energetic time is before meals, that is, from three to five o'clock. If you choose to exercise after meals, it will be one hour after meals. Improper exercise will affect gastrointestinal digestion, which will affect gastrointestinal function in the long run.
It is best to exercise three hours after a meal, because the pressure on the stomach just after a meal is relatively high, and it will do great harm to the stomach if you exercise immediately. You can't eat for about an hour after exercise. At this time, the metabolism of the body is basically stable, which is conducive to the absorption of food.
After exercise, you can add some food: for example, drink milk, eat beef, chicken and fish, preferably egg white. You can eat some fruits before exercise, such as apples, oranges, lemons and other substances rich in Vc.