It doesn’t really make any sense how this could possibly be related, and for that reason I don’t rule out some other factor being at play, but the correlation has been pretty evident on all 3 occasions when I tried to do this and the absence of the same effects when I don’t do this and instead do pre-boil the pasta all seem to point it being the relevant variable.
Assuming the no-pre-boiling somehow is responsible, the obvious solution to the problem is to just stop doing that and indeed I have for fear of a repeat of the horrible experience, but it’s just that the ease and efficiency of the method is so appealing and I would like to try it again, but I also really don’t want to gamble on that unless I can be pretty well assured that the results were unrelated to the lack of a pre-boil or if that actually is a plausible cause, I’d like to learn by what mechanism this could possibly play a role and why it doesn’t bother most people.
That does sound weird. I assume it’s regular wheat pasta?
Do you have pain in your stomach or intestines?
The first thing that comes to mind is resistant starch. Pasta that has been boiled and was subsequently cooled changed its structure making it less digestible.
But if a high carbohydrate load is the problem this should not be specific to pasta. Do you have similar symptoms when you eat a lot of carbohydrates in a single meal, e.g. bread, rice, potatoes, etc?