Some good stuff in this thread.
I know plenty of folks who perform well athletically with the LCHF type of eating.
Personally, I fall into the category of getting too stringy when I cut out carbs, but I will admit I've never given it more than a few weeks to get my body to adapt.
Regardless, cutting out sugar, refined foods, and seed/vegetable oils seems to be key, then adjusting carb levels depending on goals.
The food pyramid is shit.