I am not sure about the fuzzy head notion. This idea appears to have propagated on the Web from the Wiki discussion about fructose malabsorption. The only thing I have found in the research literature are a couple if papers that show that fructose malabsorption appears to promote the onset of depression and depression can result in a fuzzy head, difficulty concentrating and dizziness.
I know what you mean about pizza and rice. I have been in many situations where friends and colleagues order wonderful meals and I order a grilled chicken breast and rice. However, not having to deal with the subsequent pain, etc makes life much easier
-------------------- STABLE: ♂, IBS-D 50+ years - Science of IBS