Way to get your clean on people! Day 1 is in the books.
With clean foods you may need to eat a bit more than you think to meet the demands of your active lifestyle. Here's a great list of Clean foods and recipes http://liveprimal.com/LPrecipes.pdf
I won't mention any names, but someone eh hem Matt, texted me today stating that they were a bit light headed and fainty because they'd not eaten very much.
During my first Paleo challenge, I had a similar experience. The next day the portions were larger for every meal. For lunch that day I filled a popcorn bowl half way with spinach leafs, the rest with chopped up veggies then topped it with chicken and some olive oil. Took me a half hour to find the bottom. But it did the trick.
So, don't be afraid to feed your body.. If it's clean and lean and full of nutrients, you'll be doing yourself a favor.
Here's a good link for you endurance athletes out there..