It seems that there are three ways to reduce the overgrowth. One is to take medications prescribed by a doctor. They are quite strong and can harm other organs. It seems that they are not designed for long term use which a person on antibiotics for months or perhaps years or the rest of their life would need. Another way is to starve them.
Yeast flourish on all types of sugars and simple carbohydrates.
If you have ever made bread or seen beer being started you can appreciate how rapidly yeast grows in the presence of sugar. Just imagine that inside your body. The gases being given off are amazing in themselves. No wonder people complain of bloating. A diet such as the one recommended to us greatly reduces the food supply and can starve the yeast back.