That's due to the high fat content of peanut butter, Kleiner said.
"Don't eat fats around exercise, not in abundance, because that slows down digestion," she said. "My recommendation typically is to minimize fat around exercise, but always have protein and carbohydrates beforehand."
For the first 100 miles, my eating plan worked perfectly. I kept my water bottles filled with sports drink (I'd brought powder packets along) and snacked both on and off the bike.
At the mid-point in Centralia, Wash., I celebrated with a turkey-and-cheese sandwich and two bottles of chocolate milk.
"Chocolate milk is excellent, because it gives you a great ratio of carbs to protein," Clark said. "It gives you sodium and calcium, and is full of high-quality protein to help repair your muscles."
The celebration was short-lived, however. My legs grew more and more weary. Getting off the bike at a rest stop in Lexington, Wash., 143 miles in, I was hit by a powerful cramp in my right hamstring. It was so bad I had to use my bike as balance until the cramp passed.
I tend to cramp, and on my doctor's suggestion had been taking 400 milligrams of magnesium to help counteract that. I'd taken a capsule the day before, and another with my breakfast, and another at the 100-mile mark. Now I worried it might not have been enough.
Clark said the cramps might have nothing to do with electrolytes, however. New research has found that muscles might cramp simply because they're tired.
"When muscles get tired, they tend to get hyperactive and that's what causes muscle cramping, according to the new study," she said. "But you do what works for you. There's no harm in taking that extra magnesium."
The magnesium might have helped: That was the only serious cramp I had all day, and it was fleeting.
The ride crossed into Oregon on the Columbia River, and began a grueling stretch on U.S. 30 that contained many gradual climbs. I began to flag. I would try to latch onto a pace line, but I couldn't keep up.
I got very tired, and things got very, very dark. I began wondering if I'd taken on an impossible challenge. I started thinking about calling my wife to come pick me up, a shameful proposition with which my mind began an annoying constant flirtation.
These dark thoughts are a sign of hitting the wall, Clark said.
"Your brain relies on blood sugar, and can turn against you when blood sugar is low," she said. "Your brain starts telling nasty stories, like 'I don't want to do this, why are we doing this, I'm not having any fun.'"
I rolled into St. Helens on my last legs. The day was becoming hot, and I trudged through a mister to cool myself down before heading to the food bar.
Just looking at the sandwiches and wraps made me feel nauseated, and I knew I wouldn't be able to keep them down. But I needed to eat. What to do?
One item on the table looked great -- fresh watermelon. I gorged myself, eating six slices without a thought. I also sucked down a sports gel, which delivered 100 calories of pure sugar to my system.
I got back on the bike and rolled out of St. Helens on pure mind games, figuring no matter how bad off I was, I could still finish. It was only 30 miles, after all, just a mere training ride.
And then a miracle happened. As a pace line passed, I jumped on and found that I could keep up, even though they were riding at a brisk 21 miles per hour. The watermelon and sports gel had done the trick.
"You were just done physically. You had maxed out. And then you fed yourself," Kleiner said. "The carbohydrate loading you do beforehand can only go so far."
I'm still amazed at how quickly my body grabbed the meager fuel I had presented and used it. Clark says I shouldn't be.
"The watermelon was light and it was juicy and it gave you the carbs that you needed in your muscles and in your bloodstream," she said. "Think of diabetics who get into trouble and have to eat a piece of candy. Within three minutes, they're back in order. When your body needs energy, it gets it really quickly."