I should specify here that I’ve been eating primal-keto since just before the new year and the difference is massive even from having been mostly primal-paleo for the last handful of years. The last half of 2014 was far more strict primal-paleo than before (I make that distinction because I do use raw grass-fed dairy and a LOT of grass fed butter). There are things about a more conventional paleo diet that appealed to me and things that primal made more appealing. So there’s starchy tubers, but, really, a LOT of paleo-baking. Keto doesn’t entirely wipe that option out, but it definitely makes it less comfortable to work in.
What I’ve found is that while my wife’s food allergies are horrible, immediate and undeniable, I possibly have far more food sensitivity than she does but it is all long-term, protracted and gnarly. For example, my stomach has been a notorious curmudgeon. I would shit upwards of 6-10 times per day on average. That’s every single day as far as I could remember. Vegan, juice fasting, raw vegan, paleo, (organic) SAD, roadkill and foraged foods, whatever. If I eat anything out of line, I won’t just have a shitty day, it’ll be the next two weeks.
I’d get heartburn, heart palpitations, migraines, abdominal cramping, hungry all the time, tired, and on and on. No matter what I ate, if it includes grains and/or heavy starches, that’s what was happening. No amount of exclusionary diet was helping me spot one or the other because it was literally all of it. Keto cleared up all of those issues and very quickly.
Keto is the first time that I can remember going a day without shitting. On top of everything else that’s happened, that’s a massive stand out. Overall, I have a lot more comfort and a ton more energy (I started drinking coffee when my daughters were born, because I stopped being able to sleep, haven’t had any this year.). No other dietary change has shown me that kind of impact before and the benefits kind of stack on from there.
I really stand by Nora’s Primal Body, Primal Mind take on it: nomadic hunter gatherers didn’t all live in permanent ketosis for the most part, but they generally spent enough time in ketosis that eating a lot of carbs didn’t switch their body from burning fat to needing sugar. Because we have so many extra toxins in our world and live so sedentary, ketosis is a necessary step in righting the wrongs of a domesticated lifestyle and getting us back on track with where we should be.
So I think primal-keto is really important not because I think it’s a clear representation of a flat out “nomadic hunter-gatherer” diet, but because it’s an appropriate response and corrective measure towards undoing domestication.
And, as @andrew pointed out, part of that is breaking the Store Food metabolism that means you have to constantly eat. It’s easier to need less caloric intake than to increase caloric availability.