On Feb 4th I'll be running my next marathon… technically a winter marathon, but because it will be in Arizona, it won't feel like winter to me. Next week the weather in Calgary will be hovering around 15 below zero, while Arizona will be 15 above.
Today, however, the weather in Calgary was perfect. It was almost exactly zero degrees, which is the best I can hope for in January. So I took advantage of this beautiful, sunny day and did a 50km training run, with just 700mL of Gatorade as fuel, to get my body used to burning fat instead of carbs. The fat-to-carb burn ratio is key to marathon performance.
As with any really long run, I was successful in exhausting my body's carb supply. When this happens, a runner hits the proverbial "wall" but for myself (and I'm guessing it is the same for most people who have run a few marathons) the transition is gradual and not as shocking as the name suggests.
There is, however, a strong after-effect that I feel after running my body out of carbs: hunger! This afternoon, I ate like crazy. Lots of bread, a big bowl of chilli, a stack of peas, a couple big yams, a hunk of fish, and constant snacking throughout the afternoon and evening. But my body keeps telling me it wants more, and it will continue to do so until it has digested all this food and re-filled my liver with glycogen. In other words, this hunger will persist all day, but will be gone in the morning. I know because this has happened many times before, it is just one of the less-enjoyable parts of long-distance running.