I asked this recently in the comments section of another topic. I was hoping to get more feedback so here it is in official question form.
Many within the Paleo community recommend high fat/low carb in order to become a fat burner which is better for longevity. I can totally buy this.
BUT, many within the same circle recommend short duration but high intensity sugar burning exercise. Some claim that what you burn during exercise you burn the opposite at rest (JJ Virgin also Jade Teta from Metabolic Effect). I don't know if this is true.
WHY is burning fat good when it comes to diet, but burning sugar is good when it comes to exercise?
(I just want to add that what I am trying to figure out is what caused me to crash during my low carb high fat HIIT days).
EDIT: I realize that I did not word this well. By sugar burning exercise I mean intervals, sprinting, short duration high intensity stuff as opposed to fat burning exercise which is done at a more moderate level.