Keto flu 101
3 min read
'Keto flu' is a cluster of symptoms — headache, fatigue, brain fog, muscle cramps — that hits some people in the first week. The name is misleading: it is not a virus, it is mineral depletion.
What actually causes it
When insulin drops, your kidneys flush out water and, with it, electrolytes — sodium, potassium, and magnesium. Low minerals cause headaches, fatigue, dizziness, and cramps. The symptoms are reversible within hours once you replenish.
The fix
Daily targets during adaptation: 3-5 g sodium (salty broth, pickle juice, or just salted water), 3-4 g potassium (avocado, spinach, salmon), and 400 mg magnesium (supplement or dark leafy greens). Drink 3 L of water to carry them.
How long it lasts
For most people, 3-5 days. Athletes and heavy carb-eaters may feel it longer. If symptoms persist past 10 days, double-check your electrolyte intake — the most common mistake is under-salting food.
- Keto flu = electrolyte depletion, not a real flu
- Fix: salt, magnesium, potassium, water
- Bone broth or pickle juice is the fastest cure
- Usually resolves in 3-5 days