The most common rule for yoga is that you should wait at least 3 hours after eating to practice. But why?
You should not only be on an empty stomach – your bowels should be empty too. If you do Hata Yoga, you must ensure to leave at least 10 or better 12 hours between your last meal and your practice. That way, you give enough time for digestion so that when you get up in the morning, the body will naturally purge. If you eat late at night and get up early, the digestion will not be complete.
In traditional Indian medicine, whether it is Ayurveda or Siddha, whatever health problem you have, first they will purge your colon. If you want to be healthy, it is essential that your colon is clean. The colon cannot be clean for people who eat certain types of foods, and who have the habit of eating in between too much. Especially dairy products andnon-vegetarian food remain in the colon for long periods of time.
Anything that is not an actual part of your body should be out if you want to move your energies upward. Yogic practices are not exercises – they are methods to restructure your system. In a way, you are trying to recreate yourself by remolding your system the way you want it to be. For this to be done, there should be nothing but your body. The only thing that is okay to have is water.The source of creation, the intelligence which functions within you, treats anything else as an external substance, which will not participate in your asana.
Practicing yoga means beginning a partnership with the Creator. You cannot do it all yourself, but you can create the necessary atmosphere for the Creator to do the job. You want that which is the source of creation to become your willing partner. The first time you were made, it was not your choice – it was your parents and forefathers who decided how your body should be shaped, and how it should function. It happened from genetic memory. This is why in this culture, we refer to enlightened ones as dwijas or twice-born. Once born out of your mother’s womb – the way you were born was not your choice. But now you are reinventing and recreating yourself, step-by-step, the way you want yourself to be.
If that is to heady for you, here are some other reasons for practicing on an empty stomach.
When your body feels lighter, it is easier to move
Improved access to your core
When your stomach feels full, it is harder to feel the connection to the core
Arm balances and floating becomes easier
Because you have excess to the core
Twists and forward folds deepen
When your stomach is full, it is hard to twist and fold
Hot yoga becomes easier
The act of digestion and the feeling of fullness in your stomach can make you feel nauseous
Bandhas become more accessiable
Pranayama and breathing becomes easier
Some pranayama techniques require the use of bandhas and constricting the belly. When the stomach is empty, these become assessable.
Your practice is safer
In order to keep everything in alignment, bandhas and tension in the muscles are needed in yoga poses. It becomes harder to access the needed muscles when the belly is full which makes the practice more dangerous.
If your belly is full, it can distract you from your practice.
A full belly makes you feel sluggish and sleepy.