There’s no one-size-fits-all rule here. I, personally, wait for an hour for most workouts and for an hour and a half for abs workouts. It is important to know that muscle synthesis lasts for almost 48 hours so that you will not burn muscles on an empty stomach. But, fat loss occurs when glucagon is high and insulin is low. Therefore, it makes sense to maintain a glycogen store for extraordinary performance, all the while avoiding an insulin-spike just before your work out.
Here are a few things you can consider:
Types of meals – light or heavy:
If you had a low-cal meal i.e. less than 300 calories, then this should not stop you from exercising. However, a heavy meal calls for a wait of a few hours.
The type of workout
The duration of your wait depends on the type of workout. Unlike weight lifting or walking This is especially true for high-intensity workouts. High-Intensity-Interval Training (HIIT) or heavy cardio like running or strains require you to wait
Some people can easily exercise immediately after a meal without facing any problems, while some tend to feel sick. Experimenting can help you understand which category you fall under. Some wait for a couple of hours, but it totally depends on how your digestive system handles the situation. Only trial and error will allow you to figure this out for yourself.
Generally, you shall require a meal that is low-fat, high-carb and high-protein three to four hours before a workout. Carbs supply your body with the essential glycogen for a gym workout. If you skip carbs, your muscles will fail you when you need them the most.