You are right. It seems so ambiguous and vague, this diet thing. I had always suspected diet had something to do with my UC symptoms because I noticed that after eating certain foods, for instance, bread, onions, or processed sugar, I felt worse. My doctor told me it was coincidence and if it bothered me, just stop eating it. He claimed that food couldn't affect my UC. I always wondered about that. Why then did some people have allergic reactions to food, or when you drink alcohol it altered your body/mind? Food can and does affect our bodies. I tried to eliminate certain foods for awhile, and didn't really get anywhere with improvement. I later learned that UC symptoms, as well as other health problems we may have, can have a fungal etiology. Basically, there can be a fungal/yeast overgrowth in ones' body, maybe initiated through a treatment of antibiotics, birth control pills, steroids, living/working in a moldy environment, etc. Fungus can be systemic. It can burrow through our intestinal walls, twist and alter DNA strands in our cells, cause inflammation, high cholesterol, to name a few.
So, how does one know what kind of diet to try if there is any hope out there at all of improving UC symptoms? Well, after learning about fungus and reading of others who were helped with UC symptoms by following an anti-fungal diet, I experimented with it, even when my doctors told me not to bother...it wouldn't have any affect. The diet fatboyslim referred to is similar to that. Eliminate all the fungus feeding and fungus containing foods for awhile...grains, processed sugar, yeast. As well, the SCD has similar characteristics.
Will it help you? No one can answer that. Many have been helped following such a diet. Others claim food elimination has no affect. I don't believe that foods "caused" my UC symptoms, but I do believe that certain foods (grains/sugar) fed the fungus that was brewing inside of me for years, and caused the systemic problem. After 2 weeks of strict elimination, and taking natural antifungals, I was significantly better, and eventually all my symptoms disappeared. My doctors take on it, all coincidence. They just don't know, or learn about fungus in medical school. I am still well. I know for me it was a fungal problem. I know now what foods to limit or eat in moderation. The only way you will find out for yourself, is to experiment with such a program. If you always do what you've always done, you'll always get what you've always gotten............ Hope this helps a little.