I switched from a vegetarian to vegan diet about 1 month ago, and almost immediatley I noticed that I started feeling nauseated 2-3 times per day, usually 4 or 5 hours after eating (when I would typically start to get a little hungry again). I also noticed that when I feel so sick, also get very sleepy. Frequently this also happens after a work-out or long run.
Does anyone know what could be causing this? I eat a balanced diet with plenty of grains, fruits, veggies, nuts, beans, and soy. I also drink lots of water (and no, I'm not pregnant...)
Any advice is appreciated!