Complications of swallowing the gum and more air are only a couple of the reasons they don't want you to chew gum. The other main reason is because it causes the production of digestive juices, stomach acid. It can make you feel more hungry and with nothing in your new small stomach for that acid to break down, it can cause irritation and potentially ulcers. I do chew gum, but only to help digest after I've eaten meat, 30 minutes and then out it goes!