If you were to ask TBF coach Dan Foster about fueling, there'd be a quick answer, almost a mantra: early and often. After this week, I can totally agree with that, not even just on the performance of the day, but on its affect on subsequent days.
Sunday, I raced the 7th annual Lake Natoma Four Bridges Half Marathon (see below), and did fine, but raced that as a training run, not as a real race. Two days later, I ran 7.5 miles with Harry, and really struggled. Our pacing was ~9:20, and I was the driver of that. At mile 1, I was already gu'ing (or in my case, Hammer Gel). By mile 3.5, I felt like I'd run 8 already. By mile 6, I was exhausted, and it was taking everything I had to keep going. If I can't do 28 miles in a week, how am I supposed to do 26.2 in one day?!
In retrospect, I believe it to be 100% a fueling issue. Monday night, I did a weights workout, then went to bed. Tuesday morning, I did 30 minutes of cardio on a bike, a weights workout, and then a workout with my PT. Throughout the day, I ate about 1500 calories of food, then went on the 7.5 mile run. I was already in a deficit before I even started the run...
And the big lesson of the week was this: for the two days following it, I was tired, exhausted, and felt ill -- all from exercising on a heavy deficit. So when I think "early and often," I need to think beyond just that day, but realize that failing to do so can knock me out for a couple days. Not only does that undo the work I did by working out unfueled, but it sets me back. So early and often needs to apply to my every day life -- plan out my workouts, eat for success, and stick to the plan.