Running on Empty

It was kind of like when you decide you’re going to buy a certain model of car. As soon as you realize it exists, you see it everywhere. Parked in your neighbor’s driveway, on the freeway, an advertisement…everywhere!

About two weeks ago I read an article that touted the belief that running without fuel can boost your marathon performance. Soon after, one of the bloggers I follow mentioned using a no or low fuel strategy as well. Then another article came up from McMillan. It seemed like everyone in the world was invited to the low fuel party except me.

The theory behind it is that if you carb up before runs and continue to consume carbs while you run, your body will use the carbs first and get used to a steady stream of carbs coming in. It will get so comfortable with this set-up that it won’t want to use the other source of fuel – fat. Since our bodies only store about 2,000 calories in the form of carbohydrate but have fairly unlimited amount of fat stored (about 20,000 calories in even a super thin person), it is beneficial to train your  body to use more fat and less carb, therefore ensuring that you never run out of energy (i.e. hit the wall in a marathon).

McMillian said it convincingly well: “A great way to ensure that you will deplete your carbohydrate stores on these long, steady runs is to not eat any carbohydrates immediately before or during the run. Any carbohydrates ingested will be used by the body for fuel, and we don’t want this. We want to deny the body carbohydrates in these runs so that the muscles will become better at sparing the carbohydrate stores, more efficient at burning fat and used to running with lowered blood glucose levels. Now, many people think I’m crazy when I say this, but it works.”

I had actually first heard of this concept while training for the Ironman, but it related to cycling. I read an article about a pro triathlete who claimed he never took fuel out on long rides. He would ride for up to 6 hours without anything but water. He said his body was a fat burning machine and he saw huge performance gains from his no-fuel strategy.

In all articles I’ve read on this topic, the key to the practice of not consuming carbohydrates during workouts is to stay in Zone 2. Zone 2 is sometimes called the “fat burning zone” because it is the zone (besides zone 1) that utilizes the highest ratio of fat over carbs. If you slip into higher zones,  you will begin to burn carbs at a higher rate. If you didn’t eat breakfast and then didn’t take any fuel during yoru run, running hard is a quick recipe for disaster. I learned this lesson the hard way on Saturday! Although I did have breakfast, I didn’t take any fuel during my 13.1 mile run which was supposed to include 5 miles of half-marathon pace running. Unfortunately my fueling error meant that I was unable to complete the workout as prescribed and ended up suffering quite a bit in the final miles.

McMillan also warns in his advice that if you are used to consuming breakfast prior to and fuel during a long run, don’t just go from all to nothing. Slowly spread out your consumption of gels or sports drinks. If you usually Gu every 40 minutes (as I do), start doing it every 50 minutes at first and then wean yourself off. Once you’re able to successively complete runs over 2 hours (the key is to do this on runs over 2 hours since this is when all the carbs you have stored in your body are likely completely gone), then you can cut back on breakfast. Start eating less calories before your runs and then eventually, run with no breakfast and no calories during the run at all!

Also, don’t even attempt to not consume any fuel for a run over the length of 3 1/2 hours. The best window for non-fueling long runs is 2 to 3 1/2 hours. And remember, these are for your Zone 2 long runs. Long runs that include marathon, half marathon or tempo pace should be treated as training runs for race day and should include carbohydrate and breakfast. On race day, you’ll want to eat breakfast and consume carbs, so you’ll want to also practice this. And with any long run, make sure to consume plenty of carbohydrates immediately following the workout to get your glycogen stores back to normal and decrease recovery time.

So, do as I say (or McMillan says), not as I do. I learned the hard way last week that under-fueling without practice can lead to disaster. Although I read this article prior to my run, I didn’t head it’s advice. During my training for Surf City last year, I religiously consumed gel every 40 minutes. However, during Ironman training, I’d often end up eating breakfast just before my long run and would consequently delay the consumption of my Gu for up to 60-70 minutes into the run since I was still feeling full. I figured since I was used to going 70 minutes without fuel, that I could get through 120 minutes (not sure where the logic is there – my brain doesn’t function during long runs!) without any. I even carried 3 Gus on this run with the intent of having at least 1-2, but once my stomach wasn’t happy with me, I just decided to give this whole non-fuel run concept a whirl. Don’t make the mistake I did!

What do you think? Do you run long without fuel? Does the thought of no breakfast and no fuel during a long run scare you? Anyone going to try this now?