Electrolytes and Hydration Science: What Most People Get Wrong

The mainstream hydration message is simple: drink eight glasses of water a day. The actual science is considerably more interesting — and more actionable. Hydration isn't about water volume alone. It's about the ratio of water to electrolytes inside and outside your cells, and that ratio governs nerve conduction, muscle contraction, blood pressure, cognitive function, and a dozen other processes you care about.

What Electrolytes Actually Are

Electrolytes are minerals that carry an electrical charge when dissolved in water. The primary ones are sodium, potassium, magnesium, calcium, chloride, and bicarbonate. Each plays a distinct role:

Sodium is the dominant electrolyte in extracellular fluid (outside cells). It regulates blood volume, blood pressure, and is essential for nerve signal transmission. It is also the primary driver of thirst.

Potassium is the dominant intracellular electrolyte. It works in opposition to sodium to maintain electrical gradients across cell membranes — the mechanism that powers every heartbeat and every muscle contraction.

Magnesium is involved in over 300 enzymatic reactions, including ATP production, protein synthesis, and regulation of the nervous system. Approximately 60% of the population is estimated to be insufficient in magnesium, making it one of the most consequential supplemental targets.

Calcium is essential for muscle contraction, neurotransmitter release, and bone metabolism. Most people get adequate dietary calcium, but absorption depends on vitamin D3 and K2 status.

The Problem with Plain Water

Drinking large volumes of plain water without adequate electrolytes can actually worsen cellular hydration. Here's why: when you drink plain water, blood osmolality (concentration of dissolved particles) drops. The body responds by suppressing antidiuretic hormone (ADH) and upregulating urine output to restore balance. Some of that water passes through before it can hydrate cells.

Conversely, water consumed alongside sodium (and to a lesser extent potassium) is retained more efficiently. This is the science behind oral rehydration solutions — the same principle that makes a small amount of salt genuinely improve hydration outcomes, not just sports performance.

Hyponatremia (dangerously low sodium from overdrinking plain water) is a real risk in endurance events and aggressive hydration protocols. It presents like dehydration — nausea, confusion, headache — but is made worse by more water.

The Sodium Question

Sodium has been demonized for decades in cardiovascular nutrition. The picture is more nuanced. For most metabolically healthy, active people who sweat regularly, sodium restriction is unnecessary and potentially counterproductive. Sweat contains 700–1,400mg of sodium per liter, and high-volume exercisers can lose several grams per session.

Research from the PURE study (Prospective Urban Rural Epidemiology), involving over 130,000 participants, found that sodium intake below 3 grams per day was actually associated with increased cardiovascular risk — even for hypertensive patients. The optimal intake appears to be 3–5 grams per day for most adults.

Salt your food. Use a quality salt (Himalayan, Celtic sea salt, or similar — these carry trace minerals that table salt lacks). And if you train hard or sweat heavily, consider an electrolyte supplement.

What to Look for in an Electrolyte Supplement

The market is crowded with products that are mostly sugar and minimal electrolytes. What to actually look for:

• Sodium: 500–1,000mg per serving
• Potassium: 200–400mg per serving
• Magnesium: 60–100mg per serving (glycinate or malate form for best absorption)
• Low or no sugar (unless using intra-workout for energy)
• No artificial dyes or unnecessary additives

Products meeting this standard include LMNT, Redmond Re-Lyte, and a handful of others. Most commercial sports drinks (Gatorade, Powerade) are primarily sugar with minimal electrolytes — not optimal for daily hydration.

Practical Hydration Protocol

Morning: Start with 16–20 oz of water with a pinch of high-quality salt and a squeeze of lemon. This replaces overnight losses and jumpstarts cellular hydration before caffeine.

Pre-workout: Hydrate 60–90 minutes before training, not immediately before. An electrolyte drink 30 minutes prior improves performance and reduces cramping.

During training: 16–24 oz per hour for moderate exercise; more for hot conditions or heavy sweating. Include electrolytes for sessions over 60 minutes.

Daily baseline: Body weight (lbs) ÷ 2 = ounces of water as a rough daily target. Increase by 16oz per pound of sweat lost during exercise (weigh before and after).

Signs of adequate hydration: Pale yellow urine, no headaches by mid-afternoon, stable energy without afternoon crashes, good skin turgor.

Hydration is not complicated, but it does require slightly more nuance than "drink more water." Get the electrolytes right, and the water follows.