Electrolytes & hydration while fasting
The headache, the fog, the "I have to eat right now" — most of it isn't hunger. It's mild dehydration and low sodium, and it's the easiest thing in fasting to fix.
When you fast, you're not just skipping food — you're skipping the water and salt that come with it. As insulin drops, your kidneys also release more sodium and water. That's why the discomfort often peaks mid-fast and vanishes the moment you top up electrolytes.
What you can drink and stay fasted
- Water — sip steadily through the day rather than chugging at the end.
- Black coffee and unsweetened tea — fine for most people, and they help blunt hunger.
- Electrolytes with no sugar — a pinch of salt in water, or a sugar-free electrolyte mix.
A simple electrolyte routine
- Morning: a large glass of water with a small pinch of salt.
- Midday: coffee or tea, plus more water.
- Longer fasts (18h+): a sugar-free electrolyte drink to cover sodium, potassium, and magnesium.
Keep added sugar out of anything you drink while fasting — even small amounts can nudge insulin and end the fasted state you're after.
Fast more comfortably, with a plan
Kairo builds your window and reminds you when hydration and electrolytes matter most.
Build my plan — freeGeneral information only, not medical advice. Consult a healthcare professional before starting any fasting routine, especially if you are pregnant, under 18, have a medical condition (including blood-pressure or kidney conditions), or a history of disordered eating.