This is a pretty cool article which is relevant to both men and women, although it deals mostly with female athletes.

Like many female athletes, she strictly limited her food -- dipping as low as 800 calories a day -- to improve her performance by losing weight.

But her results were just the opposite.

"I used to wake up really tired," she said. "I used to take a lot of time off training because I was so exhausted."

Last summer, Mariash tried nutritional counseling. After about a month of sessions with dietitian Nancy Pudwill, the athlete said her energy levels soared and her performance improved. Weight loss was no longer her primary goal.

I've found this to be true to some extent for me; fatness is not as important as being in shape. Although pounds are very important in cycling; the more you weigh, the more mass you have to push for very long bike rides. However, if you are too thin, you have no energy storage whatsoever. In cycling, energy is key; you have to eat a moderate breakfast beforehand, and keep eating throughout the day. This is because basically you don't have enough energy to get through 60, 80, 100 miles, and your muscles primarily need simple sugars; it's very hard to burn fat while cycling. Hence you don't really lose that much weight when doing endurance cycling. I found that I lost the most weight when doing one long ride a week, coupled with stationary cycling at the gym 3x/week. When I did the MS150 three years ago, I weighted 155. Two years ago, when I did the ride, I weighed 165. Right now, I weigh 181, and hope to decrease this before the next MS150. But with the dissertation, i've had no time/energy to get to the gym, let alone ride a bike. I really look forward to that come January.