For an athlete, besides the negative heart and blood conditions that can arise from excess sugar intake, sugar causes inflammation. Increase inflammation increases recovery time. As Lebron states, he occasionally eats sugar during season, but cuts it out during the playoffs. Those that recover faster perform better.
The American Heart Association recommends only 25 – 35 grams of added sugar to a diet.
Sugar addiction is an American epidemic. For elite athletes understanding the toxic effects of sugar on the body helps to keep the elite elite.