I spent a fair amount of time composing a comment over on @CharlotteGFE’s blog “The Great Fitness Experiment”
(link later when off the iPad), so I thought I might as well reproduce it on my blog. Here we go
I am surprised that you classify Primal Blueprint as very low carb. Mark allows you up to 150g I believe if you are not in it to lose weight. This is 600 cals of carbs, or about 1/3 of your average daily calories I would assume, and so it is in line with other carb restricting diets like the Zone. In fact, once you have decided that you would like to eat a certain amount of protein (…meat…) and fat (…olive oil…) and assuming you want to control your calories as well you wont be able to get more than say 200-250g in anyway.
As for the “carbs are bad” discussion – I liked Kurt Harris’ “Paleo 2.0” approach on his PaNu website (link later, I am on the iPad). The point here is to be a bit more differentiated and he tries to figure out which carbs are really bad (the usual candidates are all sugars in high quantity, wheat, highly processed etc) and which one’s are OK to good, especially if consumed in moderation (eg sweet potatoes / potatoes).
As a final thought – the reason why the [potentially carb-related obesity] epidemic only started now [as opposed to right after when grains were introduced a couple of thousand years ago] is IMHO because (a) most carbs are generally neutral to bad in larger quantities, but mankind can deal with adversity up to a certain point, so this problem was under control (and/or masked by the other health problems in pre-industrial times. (b) the industrial (food) revolution has greatly increased the negative effects of carbs by refining them, adding other stuff etc, and (c) the bodies of most people have caved in to this and have become more or less impaired to dealing with carbs in the way our ancestors used to (eg Type 2 Diabetes).
The implication there is that for a large part of the adult population today, carb restriction is a necessity to limit the damage done by decades of malnutrition. For children this might be different though: a sensible carb selection (eg sugar as a treat only, no sweet drinks, few grain products) might allow them to build up a more sensible metabolism that does not need those extreme measures.