In preparation to ride the Whitney Classic with my brother-in-law, I read up a fair bit on nutrition for endurance sports.
Here’s a basic article about endurance nutrition from Hammer Nutrition, perhaps the best in the business for ultrarunning, cycling and triathlon stuff.
My executive summary of what I feel are the more important points:
1. fluid intake between 16-28 oz. per hour depending on heat and rider weight. even if you’re sweating a ton, the body can’t absorb more than 28 oz./hour.
2. the body can’t absorb as many calories per hour as it is burning, so it doesn’t help to take in lots of calories. you can only absorb 300 cal/hour and replenishment beyond that needs to be done post-exercise.
3. avoid simple sugars, complex carbs are much more effective fuel because the body is limited in how many simple carbs it can process. So Gatorade actually isn’t ideal here. (Nor is it good as a “healthy” drink for people who aren’t engaged in intense exercise, as I wrote recently.) Note that I am not critiquing Gatorade in general.
4. exercise over two hours requires protein, or muscles start to break down because the body is digesting them to get sufficient protein
5. soy (or rice) protein is better during exercise. Whey protein is quickly absorbed and better for recovery, and its use during intense exercise can result in problematic byproducts.
6. liquid fuels are preferable to solid fuels during exercise, because they are easier to digest
As applied to Graham’s and my riding the Whitney Classic: Since we weren’t riding close to aerobic threshold on the event, the liquid-fuel criteria is less important. And anyway, I see Tour de France riders taking in energy bars pretty regularly, so they can’t be that bad even for higher-intensity cycling. We did energy gels, a few bars, and Hammer Nutrition’s HEED sports drink, along with some protein supplement, and also ate some fruit at rest stops.