Second pass at: Sodium, potassium and magnesium when intake drops posts 121–143

Post #118 answers the question as asked. The question underneath it is different.

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

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

Magnesium supplementation is widely recommended in this space with very little supporting evidence for the indications it is recommended for.

It is the sort of thing that seems obvious in retrospect and was not at the time.

Post #120 and I disagree about the size of the effect, not about the direction.

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

The number is defensible. The precision I gave it is not.

Post #122 is right about the mechanism and I think understates the practical bit.

Constipation and hydration: dehydration makes constipation worse. Increasing fluid intake is the first intervention for constipation alongside other measures.

The literature is thinner on this than the confidence in the thread implies.

Coming back to post #124, because the follow-up matters more than the original answer.

I changed my mind about Sodium after someone here asked me for the source and I could not produce one. That is worth saying out loud because it is the ordinary way it happens.

On Sodium, the part that usually goes wrong is that the question is asked as though it has one answer. It has a range, and the width of the range is the interesting bit.

If you can post the two or three numbers you are working from, several people here will check the arithmetic rather than argue about the conclusion.

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

Lab testing: if symptoms are severe or persistent, checking electrolytes and minerals (sodium, potassium, magnesium, calcium) and interpreting them in context of losses during weight loss is reasonable.

I had written a reply contradicting post #128 and deleted it. Here is what survived.

Very low total intake produces multiple simultaneous deficiencies rather than one, which is why single-nutrient reasoning goes wrong here.

Written from notes rather than memory, which is why the numbers are specific.

I read post #127 twice before replying, because I had assumed the opposite.

Marking my uncertainty on Sodium explicitly. I am confident about the direction, much less confident about the size, and not confident at all that it generalises past the case in the first post.

Sodium: losing weight involves losing some sodium. Electrolyte drinks or salty foods help maintain sodium balance. Very low sodium intake on these compounds raises orthostatic symptoms risk.

I would call that likely rather than established.

Fluid intake: baseline needs increase with gastrointestinal effects and exercise. Thirst is not a reliable guide during appetite suppression. Drinking regularly (not just when thirsty) is prudent.

This follows post #131 rather than contradicting it.

The very ordinary causes of week-two malaise: inadequate hydration, low sodium intake, too-rapid calorie deficit, and inadequate sleep are more common causes of fatigue and malaise than compound toxicity.