hey outdoor girl,
when you say "you keep hearing" do you mean on the PB site in the forum conversations or are you hearing it elsewhere? Because if it's in PB forum, I suspect people are discussing very particular times in their exertion/exercise schedule or they are discussing very particular volumes of food.
I'd suggest going back to the Primal Blueprint book and read the theories discussed it in specific to insulin and fats. It's all about ratios would be the way I'd describe it--ie, if you're talking a whole grapefruit, 2 bananas and some pineapple and 1 egg, yes, I'd say that's weighted the wrong way. (some have posted eating this way, I was just using it to describe an exaggerated balance of sweets to fats)