Sodium, potassium and magnesium when intake drops posts 31–60
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.
The failure mode on sodium is boring rather than dramatic. It is almost always the step everyone assumes was done correctly because it is too simple to get wrong.
Post #29 describes the usual case. This is about the unusual one.
One more thing on sodium that took me far too long to see: the two figures people quote are not measuring the same quantity. Once you notice that, the apparent contradiction disappears.
What I can speak to on sodium is narrow, so I will keep it narrow rather than generalising from it. Beyond that boundary I do not know.
Confirming post #33 from a second method, which matters more than confirming it from a second person.
Summarising the sodium thread so far, since it is long and the answer is buried: the first reply has the method, the fourth has the correction to it, and the rest is people agreeing at length.
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.
Noting that I have skin in this question and have tried to discount for it.
Collapsed as off-topic by two members at trust level 3 or above
Post #37 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.
Magnesium supplementation is widely recommended in this space with very little supporting evidence for the indications it is recommended for.
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.
Fluid intake and electrolyte intake are separate questions and drinking more water alone can make a dilutional problem worse.
That holds for the case as described. Change the assumptions and it may not.
Collapsed as off-topic by two members at trust level 3 or above
I read post #40 twice before replying, because I had assumed the opposite.
Commercial rehydration formulations are designed for a specific purpose and are not equivalent to a sports drink, whatever the marketing suggests.
Anyone who has looked at this more carefully, please correct the record.
Picking up post #42: that is the part I would want checked first.
Potassium: similar to sodium; losing weight involves some potassium loss. Bananas, sweet potatoes, and other potassium-rich foods help. Severe depletion is rare but symptomatic (weakness, palpitations).
Baseline measurements before a substantial change in intake give you something to compare against, and almost nobody has them.
Supplementing without measuring is the default approach described here and it carries its own risks, particularly for potassium.
Same conclusion as the reply above, reached differently, which is mildly reassuring.
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.
That holds under the stated conditions and I have stated them.
Adding the measurement that post #46 says would settle it.
Rapid correction of a genuine abnormality can be more dangerous than the abnormality, which is another reason this belongs in clinical hands.
The confident version of this sentence would be wrong, so here is the hedged one.
Post #48 describes the usual case. This is about the unusual one.
My experience of sodium contradicts the reply above. I am posting it as a data point rather than as a refutation, because one person's experience is exactly that.
Sodium intake often falls sharply when processed food intake falls, and that transition is abrupt rather than gradual for many people.
Everything in post #51 holds. The case it does not cover is the one I have.
On sodium the community has more anecdote than the confidence in this thread implies, and I include my own contribution in that.
Taking post #55 at face value and following it one step further.
Orthostatic symptoms: dizziness on standing after lying down can indicate dehydration or electrolyte depletion. Increasing fluids, salt, and potassium usually resolves it.
The rule of thumb is fine; the edge cases are where it earns its keep.
I read post #55 twice before replying, because I had assumed the opposite.
Posting my sodium numbers with the method attached so they can be discounted properly. Uncontrolled, unblinded, and collected by someone who wanted a particular answer.
Very low total intake produces multiple simultaneous deficiencies rather than one, which is why single-nutrient reasoning goes wrong here.
Reporting the observation and leaving the explanation open deliberately.
Worth separating two things that post #55 runs together.
Exercise and electrolyte losses: sweating during exercise increases sodium and potassium losses. Electrolyte replacement during or after intense exercise helps maintain balance.
The uncertainty is in the assumption, not in the calculation.
This follows post #59 rather than contradicting it.
Trying to state the sodium position in a way that someone who disagrees would recognise as fair, because I do not think the version in this thread passes that test.