Dear Tito,
Yogananda did recommend not meditating immediately after a meal. Eating pulls the energy toward the digestive system. In meditation we are directing the energy away from the organs of digestion, bringing it inward and upward to the spiritual eye. So the body has a conflict. After a big meal Yogananda recommended waiting for 3 hours before meditating. If it is after just a little bit of food the time could be shorter.
Often it is good to meditate before eating. Many on this path will meditate first thing in the morning before breakfast. It should be fine to have some water before meditating if you are thirsty. Other good times to meditate are before lunch, before dinner, and before going to bed at night. All of these allow a good amount of time after a meal. See if this timing helps, and then you can eat your normal diet as you usually do.
Many blessings,
Nayaswami Mukti