If it was anything, it was that the nuts were rancid. I know that people hate it when I say this, but it may be a psychological reaction also. A little bit of sugar is not going to normally cause this. Why don't you try something else with sugar that you know is fresh? That way, you can see if it is the sugar that's causing the problem.

I have a hypothesis that the gut tends to go into a stoical mode after all of the abuse on the SAD. We only have pain mechanisms to get us to stop doing stupid stuff that gets us hurt, but it makes little evolutionary sense that if someone is forced to subside on junk (grains were paleo, but only if we were starving) to make them hurt, that makes an organism much less effective at doing its job. When we detox off of the bad neolithic junk our pain mechanisms reset and when we go back to eating junk it's that "hey that's bad for you don't eat that" response once again.

As for gut health, once you're back on paleo and feeling good I think you should take fermentable fiber (like inulin) and plenty of gelatin to give your gut more resilience, they tend to heal it for good. I definitely feel it when I eat junk wheat and stuff like that but it's not as bad as it was, I attribute it to fixing the gut. Paleo doesn't necessarily fix the gut, only take the antagonists away. Paleo can fix the gut but I think too much methionine and not enough glycine as well as too little fiber (not always necessary to have fiber for good health, but it definitely helps) can be paleo downfalls that make us less resilient to neolithic baddies.

It's probably the sugar. Just anecdotal evidence here, but then most of the primal / paleo evidence is just anecdotal. My boy has to be allowed to see his father on occasion...grrr... Anyway, I got myself a fat little Indian boy 3 years ago when I married his mother. I put him on a primal type eating program just like I am. The boy is now full of energy, feels great all the time, is slender and athletic, strong as any 9 year old should be...and doing great...much better than the sluggish, lazy, sleepy, fat 6 year old I met. Of course parental involvement, taking him out to play, taking him to run sprints and making a game of it, playing ball, etc... didn't hurt at all either.

But back on topic... When he goes to his father's house for a weekend he comes home sick. The culprit? Pasta, pizza, burritos, and ice cream. The same reason his grandparents no longer get to see him...we were tired of them bringing him back sick as in nausea, vomiting, and diarrhea for 2-3 days. When I remind his father how all humans, especially Native Americans, Indians, or whatever the proper word is these days should be eating... he says, "oh yeah, right, I forgot that's probably why all my family died from diabetes." Then does better for the next couple of visits.

Then back to eating bad and getting a sick child home a couple of months later.

I mean if the man wants to eat that stuff and croak himself over sooner...just better for me and my family...then I don't have to share my boy (hey, he is mine now)... But I do wish he wouldn't do this to my kid... But since it's his kid too, I can't stop him. But the anecdotal evidence for how the body rejects the "bad" foods is pretty clear in him.

*NOTE* When my Checz wife eats that stuff, after being primal with me for a year, it's not so rough on her, even though she doesn't feel well for a day afterwards. But my daughter (Scotch Irish, Cherokee, and Seminole like me) gets ill when she eats it, the boy child does too, and so do I.

I've gotten very sensitive to sugar and processed food substances after only a couple of months on Paleo. My wife brought home those Boston Fruit Slices (basically corn syrup in the shape of little fruit slices, like gum drops). I used to love them as a kid, and in a weak moment I had a couple. They tasted terrible, like plastic and food dye, and I felt like the inside of my throat and stomach were coated with varnish for about an hour. This might have been from the food colorings and stabilizers more than the sugar.

Another time I had a couple of malted milk balls (same thing, used to love them as a kid). Rather than being a treat, they tasted gross, and I was in the bathroom about 30 minutes later.

Another time I nibbled at some dried mango we have for the kids lunches, I did not realize how much sugar is in that. I had about a piece and a half and could literally feel the insulin surge, I felt a tingling below my sternum (my pancreas?) and felt something rush around my blood stream, and got a little dizzy (sugar rush). It was not a nice feeling. I looked at the label and 2 slices had 24g of sugar -- about 6 teaspoons I think! That is more sugar than I've had in the past 2 months combined.

These days I won't even lick my fingers clean if I am making something for the kids that is sugary.

I have eaten very strict for 6 months. Last weekend I decided to eat some birthday cake with a lot of icing. Within 30 minutes I was really nauseas and the vomited until my stomach was empty. I felt bad until the next day too. I learned my lesson with the sugar.

Sugar can certainly have this kind of effect, not on everyone and not all the time. Combined with other crap food it can overwhelm a person. People will react as per their unique physical % mental dispositions at the time.