Making electrolyte water for fasting is straightforward: you need water, salt, a potassium source, and optionally magnesium and baking soda. The reason this matters is that fasting triggers a significant shift in how your kidneys handle sodium. When insulin drops during a fast, your body starts flushing sodium and water at a much higher rate than normal. As your metabolism switches to burning fat for fuel, the acids produced require sodium to escort them out through urine. This process can leave you feeling dizzy, weak, and headachy within the first day or two, and simple water won’t fix it.
Why Plain Water Isn’t Enough
During normal eating, insulin signals your kidneys to hold onto sodium. When you stop eating, insulin drops and that signal disappears. Your kidneys begin dumping sodium to cover the organic acids your body generates while burning fat for energy. The body tries to adapt by producing more ammonium to replace sodium as the main carrier for these acids, but that switch takes time. In the meantime, sodium losses far outpace chloride losses, and you can become depleted quickly.
This is why many people feel terrible on day one or two of a fast, even if they’re drinking plenty of water. The classic symptoms of low sodium include brain fog, headaches, nausea, and fatigue. Low potassium shows up as confusion, muscle weakness, and sometimes difficulty speaking. Low magnesium is harder to pin down because its symptoms are vague and easy to dismiss, but it commonly causes muscle cramps, irritability, and heart palpitations. Replacing these minerals in your water prevents most of the misery people associate with fasting.
The Basic Recipe
The most widely used fasting electrolyte formula, popularized by the “Snake Juice” protocol, calls for these ingredients mixed into 2 liters (about half a gallon) of water:
- Sodium chloride (table salt or sea salt): 1/2 teaspoon
- Potassium chloride: 1 teaspoon
- Sodium bicarbonate (baking soda): 1 teaspoon
- Magnesium (optional but recommended): 200 to 400 mg from a supplement
Sip this throughout the day rather than chugging it. The taste is salty and slightly mineral. Adding a squeeze of lemon juice helps make it more palatable without adding meaningful calories or breaking your fast. You can also split this into two separate 1-liter batches if you prefer a less concentrated taste.
Where to Find the Ingredients
Regular table salt or any sea salt works for the sodium chloride. For potassium chloride, the easiest option is a salt substitute from the grocery store spice aisle. Products like Nu-Salt are pure potassium chloride. NoSalt is another common option, though its formula now includes potassium bitartrate and several other additives alongside potassium chloride. If you want a cleaner ingredient list, look for pure potassium chloride powder sold by supplement or bulk food retailers.
Sodium bicarbonate is just standard baking soda, the kind you’d find in any kitchen. Arm & Hammer or any store brand works fine.
For magnesium, choose a form your body can actually absorb. Organic forms of magnesium (citrate, glycinate, or glycerophosphate) are significantly more bioavailable than magnesium oxide, which is the cheapest and most common form on store shelves. Research consistently shows that solubility matters more than the raw amount of magnesium in a tablet. A 200 mg dose of magnesium citrate delivers more usable magnesium than a 400 mg dose of magnesium oxide. Magnesium citrate dissolves easily in water, making it a natural fit for an electrolyte drink. Magnesium glycinate is another good choice, though it dissolves less readily and may work better taken as a capsule alongside your electrolyte water.
Why Baking Soda Is in the Mix
When your body burns fat for fuel during a fast, it produces ketone bodies that make your blood slightly more acidic. For most healthy people doing shorter fasts, this is a mild and manageable shift. But as fasting extends, that acid load can build. Sodium bicarbonate acts as a gentle buffer, helping neutralize some of that acidity before it becomes uncomfortable. The symptoms of mild metabolic acidosis overlap with general fasting discomfort: rapid breathing, fatigue, and nausea. A teaspoon of baking soda in your daily water helps keep things in a more comfortable range.
If baking soda upsets your stomach, you can reduce it to half a teaspoon or skip it entirely on shorter fasts (under 24 hours). It becomes more important the longer you go without food.
Adjusting for Your Fast Length
For intermittent fasting windows of 16 to 20 hours, electrolyte needs are modest. A pinch of salt in your water and normal magnesium intake from food during your eating window is often enough. The full recipe above becomes more important once you’re fasting beyond 24 hours, when kidney sodium losses accelerate and your body’s acid production from fat burning ramps up.
For extended fasts of 48 to 72 hours or longer, you may need to increase your sodium intake. Some people find they need up to a full teaspoon of salt per day. The best guide is how you feel: if you’re lightheaded when standing up, your sodium is likely low. If you’re getting muscle cramps or twitches, potassium or magnesium may need a bump. Start with the base recipe and adjust upward based on symptoms rather than following a rigid formula.
Keep your supplemental magnesium at or below 350 mg per day. Higher doses from supplements (as opposed to food) can cause digestive issues, and that upper limit exists for good reason.
Signs Your Electrolytes Are Off
The whole point of electrolyte water is to prevent symptoms, so it helps to know what each deficiency feels like:
- Low sodium: headache, nausea, fatigue, dizziness when standing, brain fog
- Low potassium: muscle weakness, confusion, irregular heartbeat, constipation
- Low magnesium: muscle cramps, eye twitches, irritability, trouble sleeping
If you experience heart palpitations, significant confusion, or muscle paralysis, stop fasting and eat something. These are signs of a more serious electrolyte imbalance that food and normal kidney function will correct faster than supplementation alone.
Who Should Be Careful
This recipe assumes healthy kidneys. Your kidneys are responsible for balancing whatever electrolytes you take in, excreting the excess and holding onto what you need. People with chronic kidney disease lose that fine-tuning ability. Potassium is the biggest risk: hyperkalemia (too much potassium in the blood) is the most common electrolyte problem in kidney disease, and it can cause dangerous heart rhythm changes or cardiac arrest. If you have kidney disease, heart failure, or liver disease, supplementing electrolytes without medical guidance is genuinely risky.
People taking blood pressure medications, particularly potassium-sparing diuretics or ACE inhibitors, should also be cautious with potassium supplementation, since these drugs already raise potassium levels.