Big whoop, right? People do that -- and much more, much faster and more efficient -- all the time in training.
But, for me, it was a moderately big deal because I did it without my favorite middle- to long-distance
crutch aid: carbohydrates. I had no carbs (no banana or toast) before leaving the house and no Cytomax or gels during the run. I drank six ounces of water, tops.
There has been a lot of buzz among runners recently about carb depletion training. The thinking is that if you limit the carbs you ingest during a run it teaches your body to access the fat stores for energy, rather than just depending on the glucose your liver pumps out via carb ingestion.
Some dieticians and coaches posit that runners hit "The Wall" in marathons because they're not used to using fat as a fuel source. But by limiting carbs during training, they can access more muscle glycogen late in a race.
So, if I really wanted to awaken my sleeping fat stores, I probably should do my long runs (20 miles or so, sans gels) and see how it goes.
New York City Marathon champ Meb Keflezighi is a big proponent of the training method, as are many of the top competitiors entered in this month's Western States 100 Mile endurance run. Most runners don't do away with carbs altogether in training; they'll mix long runs with carbs with long runs without.
Here's a recent study on carb depletion, featuring cyclists (but it's the same principle).