That's a good point, but as it can take several weeks to actually feel any benefit, or the full benefit, the cutting down bit could easily prolong the experiment to be a looooong time. Before being instructed to go GF, I only had a handful of really vague symptoms, but after some weeks it dawned on my I actually had lost the majority of the symptoms. I still son't necessarily "go" every day, but myself and the Doc have concludes that's just my usual way of being.
Having done quite a lot of reading around this, I have seen feedback on both thyroid and Coeliac fora that suggest a minimum of 3 months is a suitable trial period of total exclusion.
For anyone considering they need to go GF (and it is a big and disruptive thing to consider), I would suggest (after medical testing, as the tests are often inconclusive if the carb count is already well down, and for other reasons) it might be easier to prove any food specific intolerance by a period of exclusion, then adding back, if going GF improves matters.
I'm not trying to poo-hoo anyone's approach or suggest any one way is the correct way, but just trying to feed back my experiences and personal findings.
@licklemoose - I hope your daughter achieves some clarity, whichever route she chooses.
As a matter of interest, does you daughter have any auto-immune (AI) conditions, or is there a history of AI conditions in her family history?