Meal size and food composition affect the rate of digestion, so it’s best to avoid having a large meal just before exercising, because this may cause bloating, nausea, cramping, acid reflux, vomiting, diarrhea, or sluggishness.
If your exercise routine demands a lot of energy, like running, swimming, or weight lifting then don’t do it on an empty stomach, and also make sure that you finish your meal at least one hour before you start your workout.
For lighter, low impact workouts such as walking and yoga you don’t need to eat beforehand.
Scientists have determined that a 15-minute post-meal walk can aid in digestion, help in clearing the mind, reduce blood sugar levels, and help ward off complications such as Type 2 diabetes. Consequently, after a meal, you may be better off walking at a moderate pace instead of attempting a more strenuous workout.
But if you’re not used to walking after a meal, when you first start, you might feel some discomfort, including stomach pain. To avoid any issues, start slowly by considering the length, intensity, and timing of your post-meal walks when you first start doing them.
See these recommendations from the International Society of Sports Nutrition:
Learn more about the timing and kind of food to eat to improve your exercise performance: