Anyway.... By far the best thing you can do for riding, heck, life in general is to LOSE THAT BELLY..
I am by no means an expert, I did not study nutrition in school, etc, etc... All I really have done is read a couple of books and actively seek out whatever works for other people.
First thing first, 90% of america does it WRONG! There is no magic pill, potion, etc that can substitute for eating right. It does take discipline, I won't kid ya. Nasty crap tastes great!
I have really only read two books and find one pretty good, and one great...
Racing Weight by Matt Fitzgerald
Paleo Diet for Athletes by Loren Cordain, Ph.D & Joe Friel
Both are good, and they both work. I will over simplify the two for time sake and why I prefer one over the other.
Racing weight is basically counting the calories you take in and burn throughout the day. If you create a calorie deficit of 200-300 calories then your on your way to a leaner you. The trick is keeping it within 200-300 calories. This means you get lean without losing muscle, take in two few calories and your eating away at muscle, too many calories and you guessed it big boy... You get bigger.
In order to do this you have to get your resting metabolic rate (how many calories your body burns throughout the day) and then figure out how many calories your burning when working out. Then you count the calories you take in and there you have it..
Paleo is a bit different, well about as different as you can get. The basic premise is to stay away from processed foods (which is making America larger than the rest of the planet combined) and eating purely fruit, veggies and lean protein. Where the "for athletes" comes in is you deviate from the plan before, during and after training and racing. At this time you take in more high glycemic carbs that you would not normally take in under the plan.
For me, I prefer the Paleo plan because is takes some of the thinking out of everything, other than what to eat. I don't have to look up the calorie count of this or that, I don't have to do any calculations and I don't have to keep track of what I am eating (seriously, I was looking up bananas, a slice of bread, sugar for my coffee, etc. etc.) each meal/snack all day. I have done it and it does get rather old in a short amount of time.
The hard thing about Paleo is that you have to plan ahead. Its quite hard to find quality food that is not loaded with starches when you have to juggle family/work/training/etc and your running around constantly. In today's society, crap food is the standard, even the 'healthy' food isn't all that great. Also, I know a few dudes who whoop my butt on a bike that follow it... Which never hurts its case...
I would say the biggest thing for me is that when I got lean under race weight, I did not feel strong. Yes it did get me light; but at what expense? Under the Paleo plan, with its high protein intake I can get lean, but still feel strong and for racing bikes, that kind of makes my decision a no brainer...
Again, I do want to emphasize that I am in no way, shape or from qualified to give anything near professional advice. Just a dude who likes to compete and share what helps me. All in all, go and find out what works for you, just thought I would try and help... That and I can't get any other of my Joetown peeps to post on here...