Previously I discussed methods for determining how many calories you need to eat during an ultra and various strategies to get there. I believe the method outlined before is still the method used by the majority of the athletes in a race, elites and back-of-the-pack folks alike. But my personal experience has given me some reservations about this strategy.
My primary problem is that I believe I am drinking too much, as much as 24-40 oz per hour. Depending on consuming so many carbs via beverage forces me to drink a ton. Worse, on hot days, the sugar in my beverages leaves me with a feeling of cotton mouth and makes me want to drink more. During the Leadville 100, I was the same weight at the end as the start of my race. And I was urinating every 45 minutes or so, particularly in the middle of the night. If you have followed the work of Tim Noakes in his book Waterlogged, then my description above probably strikes you as excessive and maybe even a little dangerous. Noakes suggests that we should be a little dehydrated and that the dehydrated athletes often do the best by going into a state of temporary dehydration as their body adapts to the stress of racing. Transient dehydration is temporary and our bodies can remain in this state for some time (like 4-8 hours) without being in jeopardy. And, if we listen to our bodies, we'll probably become thirsty and forced to slow down at about 2% dehydration. The mantra among those that follow Noakes has become "drink to thirst" and forget salt. (While Noakes suggests salt is not necessary, he acknowledges that moderate amounts don't hurt either.)
The other problem that I have with the previously laid out nutrition plan is that I am a relatively large athlete. My 190+ pound racing weight translates into a very difficult to accomplish goal of 350-400 calories per hour in a long race. Not much tastes that good and cramming in 400 calories is awful during race conditions. And, many of the high carbohydrate sources begin to give athletes GI problems in portions that high over long enough time periods. These GI problems are individual to everyone, but it is not uncommon to experience them during or after a race.
Enter the "Holy Grail" of nutrition plans, as described by Ben Greenfield. A similar strategy was used by Jason Schlarb to win the Run Rabbit 100 this past September, where he reportedly ate only 1500 Kcals in 17 hours! Sure, he probably weighs 135 pounds and runs 100+ miles a week, but still, that is ridiculously low. Also, see Timothy Olsen's nutrition plan.
So what is this Holy Grail plan? The summary is that you go into extreme fat burning mode and consume only the most slow burning carbs (such as Generation Ucan*), easy to digest fats, and water. The trouble with sugar or maltodextrin sources of carbs is that they spike your blood sugar, which causes your body to prefer to burn carbs, requiring you eat more carbs. It is a vicious circle. Ben Greenfield also recommends Master Amino Acid Pattern, which I have been taking for over a year. These pills basically provide your body with easy to absorb amino acids that help protein synthesis to stave off central nervous system fatigue and muscle wasting. I use these pills with ANY nutrition strategy. When you put all the pieces of this plan together, it is possible for a well-trained athlete to consume only 100-200 Kcals per hour and perform.
What's the catch and why doesn't everyone do it? Well, the first problem is that your body has to be extremely fat adapted. This typically starts with your everyday diet. Both Ben Greenfield and Jason Schlarb follow a low-carb-high-fat (LCHF) diet. They do not subscribe to the theory that you must eat disproportionate amount of carbs to train at a high level. It can take months to transition to this type of diet, not a small undertaking when you are trying to train for a race. The good news is that I have been following the Paleo diet for nearly two years now, and the Atkins diet before that. So, I am somewhat familiar with low-carb. Ketosis is a totally different animal. Similarly, training to get to this level of fat adaption is going to feel sluggish for a while. Personally, I like to do 85% of my running across a given year in Zone 1 and Zone 2 to ensure that I am nearly totally aerobic and burning mostly fat. This type of training requires a lot of time (at least 8-12 hours a week when training for a race), a heart rate monitor (and an understanding of what that data means), and extreme patience and discipline.
The other difficulty with this plan is that Generation Ucan is not cheap and not particularly easy to work with. Because it is a super starch, it comes in a really fine powder that is hard to mix, particularly on the run. It also doesn't taste tremendous. Ben Greenfield's solution -- which I aim to try -- is to mix several servings of the plain flavor into a gel like consistency with a flavor adding agent into a small flask/handheld. A flask or handheld should provide many hours of sustained energy in a relatively small container. Take one mouthful every 30 minutes and you are done! Of course, if your plan is to run 100 miles, you'll have to have more of it ready to go in crew stations.
Another viable option, and one I think many people will likely end up doing, is to start with a Ucan based plan for the first half to two thirds of a race and then switch to an "anything that sounds good" plan for the remaining portion of the race.
* A quick little side note to acknowledge that Ucan has many uses and endurance racing is only one of them. Many athletes prefer it as their carbohydrate source for shorter distance racing, CrossFit, etc.. My purpose here is just to illustrate the difficulties facing an athlete that plans to race for longer than a marathon and up to twenty-four hours.