mateo44

For me, I like about 500 calories for breakfast before a ride (maybe a bit more if it's a century), then about 150-200 calories per hour while on the bike (maybe more, depending on the intensity). Those calories come from a combination of liquid (usually G20 or accelerade), "real" food (sometimes fig newtons or Clif bloks or something like that) and gels. I also think gels are great (especially the kind with caffeine, since I usually cut back on coffee before a big ride).

Note that some energy drinks (like accelerade) have protein; others (like Gu20 or cytomax) do not. Some peoples have sensitive stomachs when it comes to protein during rides. Some bike shops sell single-serving packets of the various drinks -- you might want to buy a few and figure out which work for you. That way you avoid buying the 4-pound drum and discovering that it makes you sick. And, if you can't tolerate the flavor, you won't drink it during the ride -- also bad news. It's important to find one you'll drink -- and don't forget temperature. If you like it cold, you might not like it luke-warm.

Since there's so much variation in people's tolerances and preferences, it's hard to say what's "best." What's best for you'll figure out with experience and good old trial-and-error.

I do know, though, that I've seen lots of people on centuries stuffing their faces at every rest stop. It's very important to eat enough during a ride of that duration, but it's also very prudent to avoid over doing it. Small, frequent intakes (as Valygrl suggests) is a great method. There is a maximum rate at which one can absorb carbs -- going above that is a recipe for feeling sick to your stomach. But try not to get to the point when you're hungry -- you should eat before that (just as you should drink before you get thirsty).

If weight loss is any part of your motivation, I'd be very careful about eating on the bike -- make sure you do it (but prudently)! If you don't, and you think you'll save calories that way, you'll just eat them ALL back at the end, when you are absolutely famished at the ride's end. You want a pretty level blood sugar level throughout the day. If you do things right, you shouldn't feel starving at the end. That way, you can eat a reasonable (but somewhat large) meal, and still have a nice calorie deficit for the day.

Good luck!