I have celiac disease and soy allergies. I am also unable to tolerate certain carbs in certain quantities--anything from tomato paste to mashed sweet potato to coconut flour to white rice turns my digestion to sludge. The results are replicable and quantifiable. I can induce bad digestion by eating a threshold quantity of these substances (anything over about 10 grams). I have eliminated these items from my diet but occasionally give in during social events. Interestingly, raw tomatoes or boiled sweet potatoes do not induce the same response. Can you help me explain this? Are there any references out there that speak to this? (A search of PubMed on "carbohydrate intolerance" reveals much about lactose, but little else of value.)
If I eat any carbs beyond the tiny amounts in meat and fats - doesn't matter the source - I suffer. I wish this weren't the case. If I eat leafy greens, I am in digestive pain and I spin into an out-of-control situation where I am stuck in the universe of insatiable hunger. From greens! It's hell. Or it's heaven, take your pick. All I can eat, safely, and keep my appetite in control as well as my tummy happy, is meat and fat and a bit of cream and butter. That's it. That's all I eat, and all I have eaten for nearly a year. I look great, I feel great, so it's okay. But some days I wish I could eat an apple, for crying out loud, or some salsa. But I can't. Will my system ever "heal" or is this the way I was born? I have no idea.
I eat about three pounds of meat and fat a day, to keep my weight up and to keep my energy and mood up. I feel fantastic.
I think that there are others like this, too, who have a very small margin of error with their diet. We are all different to a degree.
Good luck figuring out where your margin of error lies, and don't be too discouraged if it is like mine. Meat is super yummy!
It sounds more like you have some sort of starch intolerance, probably confounded by other factors which make figuring out the actual problem more difficult. In this case, "intolerance" is akin to lactose intolerance; some amount of undigested starch passes to your gut where it is fermented by bacteria. You sound very strongly like someone who has an undiagnosed bowel disorder (Crohn's, Ulcerative Colitis, etc) and the byproducts of starch digestion may very well be your trigger.
Here's a blog post I wrote up explaining my understanding of the theory/mechanism involved: http://crohnscarnivore.blogspot.com/2010/06/hypothesis.html
Your ability to eat raw tomatoes and boiled sweet potatoes does confound things. If you are so sensitive that 10g of white rice will set you off, boiled sweet potatoes probably should as well.
For what it's worth, there's no real concept of "carbohydrate" intolerance since it's too vague. If you were really intolerant to an entire macronutrient, your body would be in dire straits. What's more likely is that you are sensitive to some particular thing which might be two steps removed from the food itself (like an immune response to bacterial digestion by products).