Carbs and Exercise
I'm starting to think that one's carb intake should be somewhat affected by their level of activity. The more active you are, the more lenient you can be on the carbs since they won't be affecting your insulin sensitivity as much. I was thinking about those "raw food vegans", who get all their calories from fruit (sugar). The only one's I've seen that look in shape also work out intensely, mostly long-distance running. I can't imagine an all-sugar diet being beneficial to someone with only moderate exercise.
While the majority of one's calories should be from healthy fats, the exact proportions of carbs should be somewhat affected by exercise level.