While some of us are inherently gifted in this regard, others generate a whole bunch of power but also carry a whole lot of weight, so we are always trying to lose a few pounds. But if we lose a lot of weight very quickly, we sacrifice some power in the process and change ourselves from fat-guys-who-can't-climb into slightly-less-fat-guys-who-still can't-climb. And without all that power, we're slow on flat roads, too.
All of this is probably common knowledge amongst Bonobos in the the know. (That line is funny because of assonance, the repetition of a vowel sound within a line.) However, a more dangerous consequence of losing too much weight too soon is much less widely known, so I've posted the following image as a reminder: don't restrict too many calories!
You can't win a sprint if you're locked up in a plastic cage.