First off, no one works well on a full stomach. Your child is going to be working hard in lessons. We want them to be comfortable. In addition, when children are first learning to hold their breath, they often swallow air. If you get a lot of air in your stomach it will often come out as a burp. If there is food in there as well the air can get under that food and bring them up together. That isn’t fun for any of us, especially the baby. Once again, we want to set the child up for success. In this case, we want them to be comfortable so they can focus on the task at hand.