Why electrolytes are critical on keto
The first days in ketosis, your body releases water (1 g of glycogen retains 3 g of water). With that water go sodium, potassium, and magnesium. Without replenishment, the keto flu kicks in: fatigue, headaches, cramps, brain fog. 90% of early keto "failures" come from electrolyte deficiency, not the diet itself.
Sodium: 3-5 g per day (yes, 3x the average recommendation)
On keto, the kidneys excrete more sodium because insulin is low. Government recommendations (2.3 g/day) are calibrated for high-carb diets, not yours.
Sources:
- Salt your food generously (Himalayan pink salt, sea salt)
- Salted bone broth (1 cup = ~600 mg)
- Olives (5 Kalamata olives = ~400 mg)
- Canned sardines (1 can = ~500 mg)
- Real pickles (no sugar) = 300 mg per serving
Morning trick: 250 ml water + 1/4 tsp salt + 1 tsp lemon juice = a free electrolyte drink.
Potassium: 3-4 g per day
Potassium regulates intracellular balance and prevents cramps. Hard to hit through food alone, but possible.
Keto-friendly sources:
- Avocado: 700 mg per medium fruit, the absolute champion
- Cooked spinach: 840 mg per 100 g
- Salmon: 500 mg per 150 g
- Mushrooms: 400 mg per 100 g
- Broccoli: 300 mg per 100 g
- Full-fat plain Greek yogurt: 250 mg per 150 g
⚠️ Potassium supplements: very dangerous at high doses (cardiac arrhythmia). Never take without medical advice. Aim through food.
Magnesium: 400-500 mg per day
Magnesium improves sleep, reduces nighttime cramps, and plays a role in 300+ enzymatic reactions. Deficiency is very common, even off keto.
Food sources:
- Pumpkin seeds: 168 mg per 30 g
- Almonds: 80 mg per 30 g
- Cooked spinach: 80 mg per 100 g
- Salmon: 30 mg per 150 g
- 90% dark chocolate: 80 mg per 30 g
Recommended supplement: magnesium bisglycinate (300-400 mg) at bedtime. Better absorbed than oxide, doesn't cause diarrhea like high-dose citrate.
Common pitfalls
Plain water is not enough
Many people drink 3 L of water "to be safe" and worsen hyponatremia (sodium deficiency). Water dilutes your remaining electrolytes. Always pair water with salt.
Store-bought electrolyte drinks
Gatorade, Powerade, Vitaminwater = sugar. Stick with homemade salt water or sugar-free brands (LMNT, Re-Lyte). Read labels: if > 1 g sugar, skip it.
Multivitamins instead of targeted electrolytes
Multivitamins contain ~50 mg of magnesium and 0 sodium. Largely insufficient on keto. Target each electrolyte separately.
Ignoring body signals
Nighttime cramps = magnesium. Headaches = sodium. Heart palpitations = potassium. Learn your "electrolyte language" and respond before the keto flu sets in.
DIY electrolyte drink recipe
Per 1 L water:
- 1 tsp pink or sea salt (~2,300 mg sodium)
- 1/4 tsp potassium-based salt like "Lite Salt" (~600 mg potassium)
- 1 tsp lemon juice (vitamin C + flavor)
- Optional: 1 g magnesium glycinate powder
Cost: ~5 cents per liter. Compare to $4 per LMNT packet.
Keto plan with built-in electrolytes
For the full picture on this topic, check our complete keto diet guide: the science, macros, food list, 7-day plan and FAQ in one place.
The Cetona app naturally integrates the right electrolyte sources (avocado, spinach, salmon, olives, broth) in the early days to minimize keto flu. No spreadsheet required.