The headache that turns out to be dehydration posts 151–159

A note on scope: what I am saying about headache applies to the case in the first post and I would not extend it further without checking.

Picking up post #149: that is the part I would want checked first.

Where the headache reasoning breaks down for me is the step from the group result to the individual case. That step is almost never argued for.

Coming back to post #149, because the follow-up matters more than the original answer.

Commercial rehydration formulations are designed for a specific purpose and are not equivalent to a sports drink, whatever the marketing suggests.

I think the headache question is answerable and has not been answered, which is a more optimistic position than most of this thread.

Symptoms attributed to electrolytes here are non-specific and overlap with dehydration, low intake and poor sleep. Attribution from symptoms alone is unreliable.

Adding the measurement that post #153 says would settle it.

Headache has been discussed here with more heat than it deserves, mostly because two definitions have been in play the whole time.

I had written a reply contradicting post #153 and deleted it. Here is what survived.

The most useful thing anyone has posted about headache in this category was a table of what had been measured and by whom. That is what I would want again.

The most useful posts here describe what was measured, what was changed, and what happened, in that order.

Marking that as an opinion rather than a finding.

Thank you — that answers what I came here to find out.