Originally Posted by Darryl Shaw
I could go on and on about how the largely plant based diet of our forebears affects our biochemistry but I'll stick to the simple fact that our bodies need to remain slightly alkaline (ph of around 7.4 if memory serves) and as fat has a nearly neutral PRAL value the only diet that makes sense in terms of balancing the acid load produced by animal foods (and grains if you're inclined towards the neolithic) is one with a plant to animal food ratio of 70 - 80% plants and 20 -30% animals and when you break that down into macronutrient ratios you end up with ~65% carbs, 15% protein and 20% fat.
Darryl, if you look back at this thread, you'll realize that the original instructors are arguing for a grain-based high carbohydrate diet. If you want to argue that point, go for it, but you'll be wrong. I think you are arguing for a high paleo carbohydrate diet -- I'm not sure if you are arguing for high paleo carbs by volume or by calories -- there's a huge difference since paleo carbs tend not to be nutrient dense.
As I'm sure you also know, our paleolithic ancestors subsisted on a wide range of foods, from the Inuit who ate a high fat very low carbohydrate diet, and did quite well, to the pacific islanders who ate mostly coconuts and fish, to the !Kung San who eat 60% (by volume) mongongo nuts and meat, 40% plants, and by calories, eat 60% fat, to Native Americans, who ate anywhere between high fat and protein diets supplemented by plants, to California Natives, who ate 50% acorns, by volume.
You aren't going to find paleolithic evidence for high grain or sugar-based carbohydrate diets, which is what the dietary reference in the original post was advocating.
Again, if you want to argue for a diet that is high in greens, tubers such as turnips and sweet potatoes, and fermented corn, you can find some justification in our nutritional past and in the nutritional present in longer lived communities. But that's not what's being argued by the nutritionists, and there's equal evidence for a high fat moderate protein diet supplemented by plant material.