" Body weight and body-fat percentage have no meaning in isolation for endurance athletes. These variables have meaning only in relation to performance. Weighing 145 pounds is not better than weighing 155 pounds unless you perform better at the lighter weight. A body-fat percentage of 12 is better than a body-fat percentage of 13 only if you’re faster at 12 percent. "

― Matt Fitzgerald , Racing Weight: How to Get Lean for Peak Performance