There is such a thing as too big a messup and I experienced it when I was on my honeymoon. I ate tons of white flour, processed foods, sugar, fruits, etc. (basically a bunch of junk) and I started to have seizures again afterwards. My angular chilitis came back.
I also messed up early on in my treatment and ate things like sunflower seeds, rice, milk, etc. and these all set back my treatment. By following the allowed foods list I was able to get better much faster.