Does the Hay diet (essentially not mixing protein based food with carbohydrate based foods in the same meal) actually produce good results? Are such restrictions unhealthy or excessive?
I have never heard this called the 'Hay diet', but I am familiar with the concepts involved here. From my learning, it's simply called 'food matching', and simply talk about which foods should be eaten with which. The basics, as I've learned them, go like this and are pretty simple:
That's it. The thought behind it is to not give your stomach things with two different digestive needs at one time. I've mainly seen it used in people with chronic heartburn and other stomach problems, and the results there have definitely been very, very good. I know 3 people personally who had heartburn almost every day of their lives for 10 or more years experience relief inside of a week. I have never seen food matching used in terms of weight loss or athletic training, so I cannot comment there.