I'm not up on the specific carb diet, although I've seen it mentioned several times. My own food journey began when I had an allergy test at age 22 that revealed over 30 food intolerances. For me, that was a direct cause of leaky gut syndrome. In the meantime, I looked into why I might be having issues with these foods and learned the following:
Gluten and dairy are often common on the "no" list for people with IBS. I get diarrhea from these.
"Spicy" foods come from the nightshade family. Nightshades include all peppers (except black pepper), white potatoes, eggplant, and tomatoes. Nightshades produce solanine, which acts like a natural pesticide for the plant. In people, nightshades cause inflammation. When I eat nightshades, I get joint pain and burning eyes.
More people are developing corn and soy sensitivites, as well. Corn and soy are found in most processed foods under different names, making them hard to avoid. Corn is ascorbic acid and corn syrup/high fructose corn syrup. Soy is also lecithin and textured vegetable protein. Both corn and soy are often genetically modified nowadays, and no one has tested the effects of that on people. (See the documentary: The Future of Food).
There are also some food additives and chemical processes that we are exposed to, while previous generations were not. One of them is hydrogenated oils, or trans fats. These fats are chemically altered and very cheap and easy for the food industry to use. However, the body cannot process them very well, because they're not what nature intended. I always get diarrhea when I eat them. They are in almost all fast foods, even the ones that claim "Zero grams of trans fat per serving!" They're legally allowed like .5 grams "per serving," and if they shrink the serving size, they can use more trans fats. (See the documentary: InGREEDiants for the exact amount). Trans fats are also in all the major brands of breads, buns, crusts, rolls, etc. Companies are getting more creative with their labeling as consumers are learning more.
Other food additives that tend to be more involved with neurological issues include artificial sweeteners, artificial dyes, and flavor enhancers. The flavor enhancers go by 30 different names, the most common of which is MSG. If you keep craving the food, you'll keep buying it. I react to these in large enough quantities--I get headaches
and vision/balance issues.
I manage my symptoms by avoiding foods that are problematic, the list of which keeps getting longer and longer. I'm starting a program with a nutritionist shortly for Candida and leaky gut, so I'm hoping to lose some of these extreme sensitivites to things like canola oil and balsamic vinegar.
Not sure if this is useful to you, but I figured I'd try. Best wishes!