Why most electrolyte products are underdosed (and what you actually lose in sweat)

Walk into any pharmacy or supermarket in Europe and pick up an electrolyte product. Read the back of the sachet. The number you're looking for is sodium, expressed in milligrams.

You will almost certainly find a number between 150 and 400. Often closer to 200. The product will then make confident claims about hydration, performance and recovery. The maths does not support those claims.

How much sodium you actually lose

Sweat sodium concentration varies dramatically between individuals — somewhere between 200 and 2,000 mg per litre. Sweat rates during meaningful exercise sit between 0.5 and 2 litres per hour, depending on heat, intensity, body size and acclimatisation.

Multiply those out and you get a real-world hourly sodium loss in the range of 500 to 2,000 mg. The American College of Sports Medicine has published the numbers repeatedly. EFSA's own physiological reviews land in the same place. This is not contested.

The shelf reality

Now compare that to what's on the shelf. The most popular European electrolyte tablets clock in at 250–350 mg of sodium per serving. "Sports recovery" sachets land between 200 and 500. Even the products marketed specifically to athletes rarely cross 600.

If you're sweating out 1,200 mg of sodium per hour and replacing it with a 250 mg drink, you are not rehydrating. You are diluting yourself. Your blood sodium drops, your kidneys dump more water, and you feel worse — not better — after drinking.

What "enough" actually looks like

Sports nutrition literature converges on roughly 800–1,500 mg of sodium per litre of fluid replaced during sustained activity. This is the dose that maintains plasma sodium and supports water absorption — not the dose that minimises taste complaints.

Repleo is built around 1,000 mg of sodium per stick. It's not arbitrary; it's the middle of that physiological range. We don't sell it as "extreme" because there's nothing extreme about meeting the dose your body is actually losing.

Who under-dosing actually serves

If you're sitting at a desk all day in a temperate office, drinking water and eating a balanced lunch, a 200 mg sachet is fine. It's also unnecessary — you'd get more sodium from a slice of bread.

Under-dosed products are designed for the demographic that doesn't really need them. The customer who actually needs electrolytes — endurance athlete, tradesperson, parent in a heatwave, person on a low-carb diet, hospitality worker pulling doubles — is the one being short-changed.