I remember a discussion from a few weeks ago, and there was debate about consuming calories while training. I just came across this:
"Consuming enough calories is more important than the form of the calories. With endurance athletes, research suggests the faster finishers consume more calories than the slower finishers. (Ironman Champ Chrissie Wellington consumed about 335 calories/hour when she won at Hawaii.) The challenge is to train the intestinal tract to manage that much fuel. If you are an endurance athlete, part of your training program is to practice your fueling so you can train your intestinal tract as well as your heart, lungs and muscles
." (Nancy Clark, MS, RD, CSSD (Certified Specialist in Sports Dietetics))
It's only a snipit from the article, but it says what I was trying to type better.