I am going to go for my first full marathon ever this weekend. Being a paleo for the last 2 years, I have been thinking of doing an experiment on myself during my run: I want to go marathon in a fasted state, hoping that I can tap into fat burning mode during the race. Help me hack this idea, please. Of course, by asking this question, I, or shall I say, we, have crossed the topic of 'chronic cardio' or 'running is not paleo' talks. I respect people from this camp, but I got a race I want to run now.
Now a little bit of my background: I have been paleo for 2 years and lost 35 lbs in the early months of it. Ketosis is not new for me. I sometimes IF randomly, 16/8. For my marathon training, I have been running regularly with long runs on the weekends up to 20 miles. My training is a bastard version of Hal Higdon's novice 2, some skipping short runs and focus on the long weekend runs. During those long runs, I fuel myself with non paleo stuff: Bagels/white bread toast before run, Cliff shots every 30-40 minutes, and Nuun electrolytes. Performance wise, I always feel miserable in the last 2-3 miles of these long runs, and took a day to recover. I don't know why why it didn't click at me during those run to fully harness the paleo force, but after reading Anthony's comment in [this thread], I decided to try run in fasted state. Because I am already in tapering mode on my training, I was able to run 3-4 times fasted up to 9 miles. I felt great on those runs, and recovered quickly.
Now, help me consider if this is a feasible idea. Right now I am planning to eat light paleo dinner the night before the race, skip breakfast and then run. I will start eating cliff bars at mile 6-9, only if I am hungry. For hydration, I'll carry my own electrolyte water and add extra water from the stations. Further ideas on mid race fueling is also appreciated.
I wouldn't skip breakfast. At the very least eat a big protein and fat (especially coconut oil) breakfast. More likely I'd go for that plus a couple of mashed sweet potatoes with a ton of butter.
If you're fat adapted you should have no problem transitioning back to fat after your meal glucose is burned.
I run ultras and I've made it about 14 hours with Paleo-mostly fueling. I use fruit primarily, which isn't all that useful for you in a marathon setting since that's hard to carry. I would suggest getting some of the Honey Stinger gels (the blocks in Orange Blossom flavor are very awesome and all their gels are gluten-free!) for your primary fueling and some almond butter packets if you can find them. You don't have a lot of time to gather up your food and test your fueling strategy though.
Are you going for an all-out effort or just cruise it?
Don't do it man. You've left it too late.
You can run in "fat burning mode" by simply running at a very low intensity.
If you want to become "fat adapted" then you need to be in ketosis for at least 3-4 weeks (according to Volek and Phinney). During the fat-adaption period you'll suck big time. I'm only a 10k runner, but I suffered during the keto-adaption phase, although not as bad as Peter Attia: http://livinlavidalowcarb.com/blog/the-llvlc-show-episode-560-dr-peter-attia-has-declared-war-on-insulin/13717
I don't think you should be trying novel new fuelling strategies during a marathon (that's what your long runs are for).
Good luck, and make sure you let us know how you got on.
Since you have not made long runs without prior carbs, I don't recommend doing for your longest run yet. Suggest you eat lot of starches and fruit the last 2 days. Pre run meal could be anything, just not to much. Drink water at energy drink during the race (or eat banana with water). Good luck!
Even if you are fat adapted, you still need to consume about 60g per hour of glucose to help aid fat burning. this is necessary. That is why u suffer cramps. Not like a huge gel, just a handful of berries are a couple of dates. Also, if you are fat adapted, you must drink much less water. Lots of water is needed by carb users as glucose needs to bind to h2. Fat adapted drinking too much water will dilute your electrolytes in your body and you may end up with cramps too. But most important is that you should be running regular long distances over a period of 6 months for your body to be strong and have less of these problems. A good tip is that if you are training for a 42km race. Double up your training to meet that distance by running 20km the Saturday and then 20km the Sunday. Once your body is in that tired state it will repair stronger. After than you can start testing glucose and water consumption on your LCHF diet as you know your body can handle the distance.