I can tick most of the boxes. A decade ago I was being investigated for a debilitating medical condition that had come on suddenly. Loads of tests and procedures over several months. Some of the symptoms seemed to mimic Coeliac disease so I decided to conduct an experiment with me as the subject. For seven months I followed a Gluten free, Soya free Vegan diet. I was also a Marathon / Ultra runner as well as being a cyclist. I never thought to get a T shirt made up 😁
( When I was eventually diagnosed I reintroduced the Gluten / Soya / and dairy on a staged basis and noticed what affects, if any there were. )