I just started eating Paleo due to noticing how much grains seem to affect my stomach. I've read that endurance type sports really aren't encouraged, however, I've already committed to running the Marine Corps Marathon this October with a friend and I'm curious if anyone else runs longer distance runs while maintaining a Paleo diet and what tips ya'll might have for me of things to eat before a run that should fuel my long runs like grains did.
Dr. Cordain wrote an entire book on it, called The Paleo Diet For Athletes. By "athlete" he is referring to endurance training.
I haven't read it (under a few others on my shelf) but Robb Wolf has said it encourages a higher carb load. Those are still Paleo carbs, though.
I just trained and completed a half marathon after being 100% paleo for the last three months. I was unable to train without adding electrolytes and some cliff blocks during runs, other things for fuel (coconut water and lara bars) during the run didn't work very well and living in the south (think hot and humid) I have seriously low sodium and needing help getting my levels back up. My running partner read Paleo for Athletes and I believe they say its ok to use non-paleo fuel for endurance training. Hope this helps!
Interesting perspective here: http://www.mcmillanrunning.com/marathonlongrun.htm regarding the long-run during marathon training. It's not paleo per se, but MacMillan seems to make the argument that, at least for long-run training, you don't NEED carbs. ANY carbs! Water, Electrolytes, yes, you can get thru NUUN tablets or the like. I trained for my last marathon this way and it was no problem for me. Keep in mind I'm a mid-pack mom, age 46, so if I could do it...
It is very doable. Rowed lightweight crew and kept paleo. Rowing a 2k is hands down more physically taxing than running a marathon. Fruit and sweet potatoes come in handy.
paleosita.com is a great site for more info on endurance training and paleo. The author is Nell Stephenson and she kicks ass.
You should also check out www.crossfitendurance.com as a training and nutrition source of information. Paleos generally don't like "chronic cardio" and the crossfit endurance method requires many fewer miles/week than typical marathon training.
Carbs = glycogen glycogen = muscle fuel
You restrict your carbs, you restrict your fuel. You need to eat good carbs, ie fruits, starchy vegetables, grains, beans, lentils, pasta. Not twinkies and doughnuts. Make it whole grain and your good to go. Limit your fat intake if your trying to run. I'm a runner and I eat high carb, I'm 6 foot and weight 138 pounds. The idea that carbs make you fat is a load of crap.
Although on Paleo, when I train I switch to a more ketogenic diet (almost no carbs). It will help you maintain a more regular supply of energy. You could look at Dr Peter Attia, he's a long distance open water swimmer who uses a ketogenic diet. He says it improved his VO2 max and his waistline.
In general you'll find keto and paleo relatively similar with keto having higher fat and even lower carbs. You should find that you no longer 'hit the wall' and you'll just have to concentrate on your physical prowess :) If you are not lactose intolerant dairy can be a great source of fat, depends on how faithful to Paleo you want to remain.