Short version: yes, for most people — the first week or two of keto flushes out sodium and magnesium faster than usual, and topping them back up is the single best fix for the headaches and flat energy people call "keto flu." Start with food (salted broth, avocado, nuts, leafy greens) and add a plain magnesium supplement if that's not enough. The one exception that matters: if you have blood pressure, heart, or kidney conditions, or take medication regularly, check with your doctor before adding sodium or potassium — this general advice may not apply to you.
Carbohydrate is stored in the body attached to water — every gram of stored glycogen holds onto roughly three grams of water alongside it. Cut carbs hard, as keto does, and the body burns through that glycogen fast, releasing the water it was holding. Sodium leaves with that water, because the kidneys process both together. That's the whole mechanism behind the scale dropping quickly in week one, and it's also why sodium is usually the first thing to run low.
This lines up with why "keto flu" — the headache, fatigue, and foggy feeling some people get early on — tends to show up in that same window. The StatPearls clinical reference on the ketogenic diet documents this adaptation period and its usual timing, and the electrolyte-specific guidance that most keto clinicians point to traces back to Phinney and Volek's work on low-carbohydrate physiology, summarized in Virta Health's sodium/potassium/magnesium breakdown. Their formulation, in short: sodium needs typically go up noticeably on keto, magnesium is commonly under-consumed even outside of low-carb eating, and potassium is best handled through food rather than supplements, since it's easier to overdo with a pill than with vegetables.
Sodium first. This is usually the fastest fix. A cup of salted bone broth, a pinch of salt added to water, or just salting food more liberally than usual covers most of what's needed for people without a medical reason to limit sodium. There's no single magic number here — needs vary by body size, activity, and how much you're sweating — which is why "salt to taste, more than you're used to" is the practical version of the advice rather than a fixed milligram target.
Magnesium second. Leafy greens, nuts, and avocado are the food sources, but a lot of people find food alone doesn't quite close the gap in the first couple of weeks, which is where a plain magnesium supplement usually comes in. This is also one of the more commonly under-consumed minerals in general, keto or not, so adding it isn't a keto-specific fix so much as a keto-specific reminder.
Potassium from food. Avocado, leafy greens, and low-carb vegetables like broccoli and Brussels sprouts carry meaningful potassium without the risk of overshooting that comes with a supplement. Unless a doctor has specifically told you to supplement potassium, food is the better route for this one.
None of the above is universal advice, and that's the important caveat, not a footnote. If you have blood pressure, heart, or kidney conditions — or take any medication regularly, including blood pressure medication or diuretics — check with your doctor before adding sodium or potassium. Sodium recommendations for the general low-carb population and sodium recommendations for someone managing blood pressure can point in opposite directions, and a generic "add more salt" post has no way of knowing which one applies to you. This is exactly the kind of thing worth a five-minute call before you change anything, not something to guess your way through.
The app's supplement guidance covers electrolytes, B vitamins, vitamin D, and omega-3 with the reasoning behind each one — no brands or doses pushed, since that's genuinely a conversation for your doctor or pharmacist. And if you're flagged for a blood pressure or heart condition at setup, the electrolyte guidance adjusts instead of giving you the generic version.
Try Keto Coach — free, no account Get it on Google PlaySources: The Ketogenic Diet, StatPearls (NCBI Bookshelf); How much sodium, potassium and magnesium should I have on a keto diet?, Virta Health (Phinney & Volek).
Keto Coach · Sloth Lab