Originally Posted by
GeorgeBMac
Your body -- or more specifically, your body's gut flora (which do a lot of the work of digesting) need time to adjust to changes in diet... That can take days and often weeks for it to shift from say, a carnivore diet to an herbivore diet. And, while it is doing that you can get some strange, unexpected and unpleasant GI effects: bloating, gas, cramps, diarrhea...
You do not say if what you ate was much different from your normal diet, but your post sort of suggests that it was.
... If so, I would blame your GI problems more on the sudden change of diet rather than the diet itself.
IMO the problem could be a combination of a sensitive digestive tract with a very high fiber food like oats and a high physical output which changes the normal action of the intestine. I always go with a very low residue breakfast before an event or long ride, even though oats and other high fiber foods are a part of my normal diet. I also eat low residue foods during the event or ride. This always works for me. I'm also careful not to eat this way more than once a week.
Sweet oatmeal soup was always my favorite after a XC race.