Best Electrolyte Supplements in 2026: For Fasting, Keto, and Exercise

Electrolytes — sodium, potassium, magnesium, calcium, and chloride — are the charged minerals your body uses for nerve conduction, muscle contraction, fluid balance, and dozens of other essential functions. When you sweat heavily, fast for extended periods, or restrict carbohydrates, you lose electrolytes faster than your diet replaces them. The result is the constellation of symptoms anyone who has tried keto or a long fast knows well: headaches, fatigue, muscle cramps, brain fog, and lightheadedness.

Most electrolyte drinks on the market are essentially sugar water with token minerals. A bottle of Gatorade delivers 36g of sugar (more than a can of Coke) and 270mg of sodium — barely a rounding error on the 1000–5000mg of sodium a keto or fasting day demands. Even the "zero sugar" versions typically underdose the minerals that actually matter.

The supplement that does the job properly is LMNT — a no-sugar electrolyte mix that delivers 1000mg sodium, 200mg potassium, and 60mg magnesium per stick. It was developed by Robb Wolf (former research biochemist and one of the early popularizers of paleo/keto nutrition) specifically because he couldn't find a product that hit the doses that worked. This guide covers why the ratio matters, when to use electrolytes, and how to think about dosing across fasting, keto, and exercise scenarios.

Why electrolytes matter (and why modern diets screw them up)

Electrolytes are the minerals that carry electrical charges in your body fluids. Sodium (Na+) and potassium (K+) are the primary extracellular and intracellular cations; magnesium (Mg2+) is a cofactor for 300+ enzymes; calcium (Ca2+) drives muscle contraction and neurotransmitter release; chloride (Cl-) balances sodium and produces stomach acid.

Your body tightly regulates electrolyte concentrations because small deviations cause big problems. Sodium too low? Hyponatremia — confusion, seizures, potentially fatal. Magnesium too low? Muscle cramps, arrhythmias, migraine. The classic advice to "drink plenty of water" can actually backfire: pure water without electrolytes dilutes blood sodium and makes things worse, not better.

Modern diets tend to create two specific electrolyte problems. First, the standard processed-food diet is high in sodium but poor in potassium and magnesium — the ratio is upside down. Second, when people restrict carbs (keto) or fast, insulin drops, and the kidneys excrete sodium rapidly along with the water it holds. This "keto flu" and "fasting fatigue" are largely electrolyte problems, not energy problems.

The sodium-potassium-magnesium ratio that works

The ratio LMNT uses — 1000mg sodium, 200mg potassium, 60mg magnesium — was designed for the demands of keto and fasting. Here's why each mineral matters and why these specific doses:

• Sodium (1000mg): The workhorse. Fasting and keto deplete sodium fastest because low insulin signals the kidneys to dump sodium. 1000–5000mg per day of supplemental sodium is reasonable for someone on keto or doing extended fasting. Standard dietary advice to "limit sodium" assumes a high-carb diet with insulin holding onto sodium — it doesn't apply when carbs are restricted.
• Potassium (200mg): The intracellular partner to sodium. Most adults are mildly potassium-deficient because we eat too few vegetables and fruits. 200mg per stick is conservative — the FDA limits potassium in supplements to 99mg per dose (historically; the rule is now relaxed but most brands stick to low doses) because potassium pills can irritate the stomach lining. In a drink mix, larger doses are safe.
• Magnesium (60mg): The most common mineral deficiency in the US. Magnesium supports muscle relaxation, sleep, and 300+ enzymatic reactions. 60mg per stick is a meaningful daily contribution; most people also take a separate magnesium supplement (see our magnesium guide).

The ratio is intentionally sodium-heavy because that's what keto and fasting demand. For high-carb athletes sweating heavily in heat, a more balanced electrolyte drink (or even Gatorade-level sodium) is fine. The mistake is using a sports drink for keto — the carbs and mineral doses are wrong for the scenario.

Why most electrolyte drinks fail

Walk the electrolyte aisle of any grocery store and you'll see the problem:

• Gatorade / Powerade: 270mg sodium, 36g sugar. The sugar actually accelerates dehydration by pulling water into the gut, and the sodium dose is far too low for keto or fasting.
• Pedialyte: Better sodium dose (490mg per serving) but still contains sugar (in original formula) and uses artificial sweeteners in the zero version.
• Propel / VitaminWater Zero: Essentially flavored water with trace minerals. Sodium content is typically 75–100mg — useless for keto.
• Liquid IV: 500mg sodium, 11g sugar. Better than Gatorade but still has sugar and is under-dosed for keto/fasting.
• Bottled "alkaline" waters: Mostly marketing. Trace mineral content that doesn't meaningfully supplement electrolytes.

The problem across the category is that these products were designed for short-duration, high-intensity exercise in a high-carb context. They deliver small amounts of sodium alongside sugar (which helps water absorption during exercise but wrecks ketosis). They're not designed for the 12+ hour electrolyte demands of fasting or keto.

Electrolytes for fasting

When you fast, your insulin drops. Low insulin signals the kidneys to excrete sodium — and water follows sodium, which is why you urinate frequently in the first 24–48 hours of a fast. This is also why the scale drops quickly on day 1–2 of a fast: you're losing water and sodium, not fat.

The "fasting flu" — headaches, fatigue, lightheadedness, muscle cramps — is largely sodium depletion. It's not the lack of food; it's the lack of electrolytes. You can fast comfortably for 24–72 hours if you keep electrolytes topped up.

For a 24-hour fast: 1–2 sticks of LMNT across the day is usually enough. For a 48–72 hour fast: 3–4 sticks per day, plus additional sodium (e.g., salt water or bouillon). Potassium and magnesium matter too — the LMNT doses are reasonable for most fasters.

See our intermittent fasting guide for the broader fasting framework.

Electrolytes for keto

Keto causes the same sodium-potassium-magnesium depletion as fasting, just more slowly. The "keto flu" of the first 1–2 weeks is largely electrolyte adaptation, not carb withdrawal. Once electrolytes are managed, most people feel fine on keto within a week.

The standard keto advice: 3000–5000mg of sodium per day (from food + supplements), 1000–3500mg of potassium (mostly from food — avocados, spinach, mushrooms), and 400mg of magnesium (from a separate supplement). LMNT covers the sodium and contributes potassium and magnesium on top.

For most keto eaters, 1–2 sticks of LMNT per day is the right dose — one in the morning and one before/after exercise. Add salt to food liberally. Track potassium and magnesium from food sources and supplement the gaps.

Electrolytes for exercise

For exercise in a high-carb context (i.e., you're not keto), standard sports drinks actually work fine — the sugar helps water absorption and provides quick energy. The issue is that most people drink them when they're not exercising, which is just sugar.

For exercise in a keto context, or for long-duration endurance work (2+ hours), LMNT is the better choice. You don't need the sugar, and you need more sodium than sports drinks provide. 1 stick per hour of intense exercise in heat is reasonable; 1 stick per 2 hours of moderate exercise is fine for most people.

For strength training, electrolytes are less critical (you don't sweat as much) but a pre-workout stick can help with pumps and prevent cramping. See our exercise for longevity guide for the broader training framework.

Our top pick: LMNT

LMNT hits the doses that actually work for keto, fasting, and exercise: 1000mg sodium, 200mg potassium, 60mg magnesium, zero sugar, no artificial sweeteners (uses stevia). The Citrus Salt flavor is the most popular — slightly salty and tart, which is exactly what you want when you're depleted.

The 30-stick box is the standard size and lasts 2–4 weeks depending on use. LMNT also sells a larger 12-stick sample pack if you want to try flavors first. The cost per stick ($1.00–1.50) is higher than DIY salt-and-potassium-in-water, but the convenience and taste make daily use sustainable.

One caveat: LMNT contains stevia, which a small minority of users find has a bitter aftertaste. If you're stevia-sensitive, look for unflavored electrolyte powders (or just mix salt + a potassium-based salt substitute like LoSalt into water with lemon).

How and when to take electrolytes

1. For fasting: 1–2 sticks per day for a 24-hour fast; 3–4 sticks per day for 48–72-hour fasts. Sip slowly over hours rather than chugging.
2. For keto: 1–2 sticks per day, plus liberal salting of food. Add a separate magnesium supplement at night.
3. For exercise: 1 stick 30 minutes before exercise; 1 stick per hour during long workouts in heat.
4. For hangovers: 1–2 sticks. Most hangover symptoms are dehydration + electrolyte loss, not "toxins."
5. For general hydration: 1 stick per day if you live in a hot climate or sweat heavily at work.
6. Don't overdo it: More than 5000mg of supplemental sodium per day can cause high blood pressure in salt-sensitive people. If you have hypertension, talk to your doctor before high-sodium electrolyte supplementation.

The bottom line

Electrolytes are the unglamorous supplement that actually matters. If you fast, eat keto, or exercise hard, electrolyte depletion is the most common reason you feel terrible — and it's the easiest to fix. The mistake is reaching for a sports drink, which delivers sugar and trivial mineral doses that don't match the scenario.

Our recommendation: LMNT. 1000mg sodium, 200mg potassium, 60mg magnesium, zero sugar, in a drink mix that tastes good enough to use daily. For most users, 1–2 sticks per day is the right dose; for extended fasting or heavy exercise in heat, scale up to 3–4.

Electrolytes pair with the lifestyle interventions in our fasting guide and longevity diet guide. For users tracking blood sugar during keto, see our CGM guide. And for the broader longevity supplement framework, electrolytes are a foundational input alongside magnesium and omega-3 in our supplement stack guide.