Bloating is a major problem for a lot of people. It can range from mild discomfort to great pain. Occasionally it can be sign of a big problem like IBS, Crohn's disease, allergies, autoimmune disease or cancer, but most often bloating and the gas that causes it are tied to what and how you eat. About half of the gas in your digestive tract is from swallowed air (usually from eating too quickly), the rest is produced by the bacteria, yeasts and fungi that reside in your gut