If one thing separates people who settle into keto comfortably from people who struggle, it is electrolytes. Get them right and most of the early misery never arrives. Ignore them and you spend your first month tired, crampy and wondering why everyone raves about this. The good news is that the fix is cheap, simple and entirely within your control, so it is worth understanding properly rather than guessing.
Why keto changes your needs
On a normal carbohydrate intake your body holds extra water and sodium. Cut the carbs and that retained water is released, taking a good deal of sodium with it. Lower insulin levels add to the effect, because insulin signals the kidneys to hold on to sodium, and when insulin falls the kidneys let more of it go. The result is that a keto eater loses minerals faster than someone living on bread and pasta, and has to replace them more deliberately.
This is the root of the keto flu, the cluster of headaches, fatigue, brain fog and irritability that hits some people in the first week. It is not the absence of carbohydrate making you ill; it is the mineral and fluid shift that comes with it. The keto flu piece covers that early-days slump in full, but electrolytes are the lever that prevents most of it.
Sodium: the one to stop fearing
Sodium is the big one, and the one people get most wrong, because they have spent years being told salt is the enemy. On keto the usual advice flips. Most people need more salt, not less, at least while the body is shedding water. Under-salting is probably the most common reason a new keto eater feels flat, weak and headachy, and it is the easiest thing to put right.
Salting your food generously is the first move. A mug of warm broth, stock or bouillon once a day does a lot of the rest, and many people find it the single most reliable cure for an afternoon energy dip in the early weeks. If you train or sweat heavily you will need more again, which is why electrolytes matter so much around exercise; the training on keto guide goes into that side of it.
There is a real caveat here. If you have high blood pressure, heart failure or kidney disease, or take blood-pressure medication, do not load up on salt without medical advice, because for you sodium genuinely needs watching. For most healthy adults on keto, though, the bigger risk is too little.
Potassium: the easy one to miss
Potassium works hand in hand with sodium, and it is the mineral most likely to fall short on a hurried, meat-and-cheese version of keto. A shortfall tends to show up as muscle weakness, fatigue and the odd skipped or fluttery heartbeat, which is unsettling but usually harmless and quick to resolve once intake comes back up.
Food covers most of it if you choose well. Avocado is exceptional, and a single one delivers a serious dose. Leafy greens, salmon, mushrooms, courgette and nuts all add up. A salt substitute that is part potassium chloride is a tidy way to lift sodium and potassium together, sprinkled on food like ordinary salt. Potassium supplements in pill form are deliberately kept low-dose for safety reasons, so food and salt substitutes are the practical route for most people rather than tablets.
Magnesium: the quiet fixer
Magnesium is the understated one. A shortfall rarely announces itself loudly; instead it creeps in as calf cramps, twitchy legs at night, restless sleep, low mood and a general sense of being wired but tired. It is hard to get enough from food alone on any diet, modern soils and food processing being part of the reason, so a fair number of keto eaters take a magnesium supplement in the evening.
Forms matter a little. Magnesium citrate, glycinate or malate are well absorbed and gentle; magnesium oxide is cheap but poorly absorbed and more likely to loosen the bowels. An evening dose tends to help sleep as a welcome side effect, and because low magnesium is one trigger for headaches, topping it up sometimes eases the head pain that overlaps with the keto flu, a connection the migraine research piece touches on. Food sources worth leaning on include pumpkin seeds, almonds, dark chocolate that is genuinely low in sugar, spinach and mackerel.
How much, roughly
Guidance varies and individual needs differ, but as a rough working picture many keto eaters aim for somewhere around three to five grams of sodium a day, roughly three to four grams of potassium, and a few hundred milligrams of supplemental magnesium. To put the sodium figure in context, that is noticeably above standard public-health advice, and deliberately so, because keto flushes more out. These are general targets for healthy adults, not prescriptions, and anyone with a heart, kidney or blood-pressure condition should treat them with caution and get personal advice first.
Signs you are running low
It helps to recognise a shortfall early, because the symptoms are easy to blame on keto itself. The usual tells are a headache that will not shift, unusual tiredness or weakness, dizziness when you stand up quickly, muscle cramps and night-time leg twitches, brain fog, irritability and a craving for something salty. Constipation often belongs on this list too, since the same fluid shifts that drain sodium can slow the bowels.
If several of these arrive together in your first fortnight, reach for salt and broth before you conclude that keto does not suit you. Most people feel markedly better within an hour or two of a salty drink, which is a useful diagnostic in itself. That rapid water shift is also why the scales can swing several pounds in a few days at the start; much of early keto weight change is water rather than fat, a point the weight-loss stall guide returns to.
The easy routine
You do not need sachets of expensive electrolyte powder, although they are convenient and some are well formulated. The cheaper, perfectly good approach is to salt your meals without guilt, drink a mug of broth when you feel flat, build meals around avocado, leafy greens and other low-carb plants, use a part-potassium salt substitute, and take magnesium at night if you cramp or sleep badly. Drink to thirst rather than forcing litres of plain water, since flooding yourself with water while under-replacing salt actually makes the imbalance worse.
The real trick is timing. Start this from day one rather than waiting until you feel rough, because by the time the headache arrives you are already behind. Front-load the salt and fluid in that first week or two, when losses are highest, and ease back to a comfortable maintenance level once you are adapted and the water shift has settled.
The bottom line
Keto makes your body shed water and minerals faster, so electrolytes move from a detail to a daily habit. Sodium is the one most people get wrong by under-salting, potassium is the one most easily missed on a low-vegetable diet, and magnesium is the quiet fixer for cramps and poor sleep. Aim higher than standard advice on sodium unless a medical condition says otherwise, lean on broth, avocado and greens, supplement magnesium in the evening, and start before you feel bad rather than after. Do that and the dreaded keto flu mostly never shows up.
This is general information about the ketogenic diet, not medical advice. People with kidney problems, heart conditions or on blood-pressure medication should be careful with sodium and potassium and should speak to a doctor before changing their intake.