Sodium, potassium and magnesium when intake drops

Worth separating two things that post #4 runs together.

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.

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.

This follows post #20 rather than contradicting it.

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 #33 rather than contradicting it.

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

Water intoxication: drinking excessive water (more than a few liters per day for extended time) without electrolyte replacement can cause hyponatremia. This is rare but serious. Balance fluid with electrolytes.

For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.

Exercise and electrolyte losses: sweating during exercise increases sodium and potassium losses. Electrolyte replacement during or after intense exercise helps maintain balance.