Beating the keto flu
The first-week slump is real — and almost entirely preventable.
What the keto flu actually is
When you cut carbs, your body sheds stored glycogen — and with it, a lot of water and electrolytes. The resulting dip in sodium, potassium and magnesium causes the classic 'keto flu': headache, fatigue, brain fog, irritability, muscle cramps and lightheadedness, usually in the first 2–5 days.
It's not the diet — it's the electrolytes
The keto flu isn't your body objecting to fat or ketones; it's mild dehydration and electrolyte loss. That's why it's so preventable — replace what you're losing and most symptoms fade fast.
How to prevent and fix it
Front-load electrolytes and fluids from day one:
- • Sodium: salt your food generously, sip broth (aim ~3–5g sodium/day)
- • Potassium: avocado, leafy greens, salmon, a potassium-based salt
- • Magnesium: nuts, seeds, leafy greens, or a supplement
- • Water: drink to thirst — but pair it with electrolytes, not instead of them
When to expect relief
Most people feel normal within a few days of dialing in electrolytes, and many feel better than before keto once 'fat-adapted' (1–4 weeks in). If symptoms persist or are severe, check with your doctor.
Frequently asked
How long does keto flu last?+
Typically 2–5 days, and often much shorter — or avoided entirely — if you replace electrolytes from the start. Full fat-adaptation takes a few weeks.
How do I get rid of keto flu fast?+
Salt your food and drink broth (sodium), eat avocado and greens (potassium and magnesium), and stay hydrated. Electrolytes are the single biggest lever.
Can I avoid the keto flu completely?+
Often yes — proactively increasing sodium, potassium and magnesium as you cut carbs prevents most symptoms before they start.