Nowhere in my post did I say you should eat a LOT of grains. Veggies have carbs too you know.
I myself enjoy a relatively high-protein diet, but it must occasionally be tempered by meatless days of a more alkaline diet and alkaline sources of protein or arthritic type pain strikes. When you're over 40 you'll probably see that the same kind of balance must be struck. Read up on the kidneys, they are precious and can be harmed by high-protein diets. Be sure to get a regular yearly physical that includes a urine test.
Most people feel better on a high-protein diet at first no matter what their blood type because they've been accenting such poor sources of nutrients. A switch to a Type O diet is fantastic at first both because of what you're cutting out and what you're replacing the junk with, but over time a building-up diet causes congestion. There's no escaping it, unless you are very careful to make your total calorie load no more than your total metabolic needs.
The Blood Type author's theories have not been verified by other scientists yet.