I don't do the ultra-low carb thing, myself. I found it good for weight loss, but then for maintenance I've upped a bit, and function much better. Having slogged through some research, I'm reasonably convinced that allowing a moderate intake of glucose is fine; I try to minimse the fructose but do enjoy a bit of fruit. Bear in mind that Primal does allow up to 100g of carbs, and for your size probably more, which is actually quite a lot. (I know I'll probably get flamed by the low-carbers for this... but each to their own. Read what Mark says about carb intake. Read the studies about gut flora, glucose and mucosa. If you're getting dry eyes, dry mouth and constipation, that's a sign you've gone too low.)
My impression is that a lot of the transition issues come from changing gut flora. This doesn't happen overnight, and you need to help it with some probiotics. I found going 'cold turkey' an absolute nightmare and have had far better results with a gradual transition. Give your body time to adjust.
Also, primal foods are more nutrient dense, and I think we therefore need to eat a lot less volume than when bulking up with loads of antinutrient-laden grain. So your tummy needs to get used to not being so full, and that will take a while. Also, being hungry sometimes (the empty tummy feeling, not the lightheaded low blood sugar type) is GOOD - it makes you a lean mean hunter! It's NORMAL! Grok wouldn't be going around with a full stomach all day like we do. So learn to put up with a little hunger from time to time.
If we’re not supposed to eat animals, how come they’re made out of meat? Tom Snyder