Electrolytes for Workouts: How Much Do You Actually Lose?
Everyone sells electrolytes. Almost nobody tells you how to work out whether you need them, or how much. Here is the math, and how to measure it on yourself.
Sweat rates during exercise commonly run 0.5 to 2 liters per hour, and sweat carries roughly 200 to 2,000 mg of sodium per liter depending on the person. A cool one-hour gym session might cost a few hundred milligrams of sodium — water and food cover that. A hot, long, or heavy-sweat session can run past 1,000 mg, and that is where an electrolyte drink starts to matter. One scoop of MNRLZ Blue Raspberry in 16–20 oz of water supplies 600 mg sodium, 444 mg potassium, and 40 mg magnesium.
What you lose when you sweat
Sweat is mostly water, but it is not only water. By a wide margin the most significant electrolyte in it is sodium, followed by chloride, with much smaller amounts of potassium, magnesium, and calcium.
Two numbers drive everything:
- Sweat rate — how much fluid you lose per hour. Commonly 0.5–2 L/hour during exercise, pushed higher by heat, humidity, intensity, body size, and clothing.
- Sweat sodium concentration — how salty your sweat is. Reported ranges span roughly 200–2,000 mg of sodium per liter, and this is largely individual. It is not something you can improve by training hard.
Multiply them and the spread is enormous. A light sweater in a cool gym for an hour might lose 100–200 mg of sodium. A salty sweater doing an hour of hard conditioning in the heat can lose well over 2,000 mg. Same workout on paper, completely different replacement need.
Are you a salty sweater?
There is no need to guess. The signs are visible:
- White salt crust or streaks on your skin, hat, or clothing after drying
- Sweat that stings your eyes or tastes distinctly salty
- Gritty residue left on dark shirts once they dry
- Cramping in long or hot sessions despite drinking plenty of water
If several of these describe you, your sodium losses sit at the high end of the range and a light 200 mg hydration product will not touch them.
Measure your own sweat rate in one session
- Weigh yourself before training, minimal clothing, after using the bathroom.
- Track every ounce of fluid you drink during the session.
- Towel off and weigh yourself again immediately after, minimal clothing.
- Sweat loss = weight lost + fluid consumed. Roughly 1 kg lost ≈ 1 L of sweat; about 1 lb ≈ 16 oz.
- Divide by session length for your hourly rate.
Do it once in a cool session and once in a hot one. The gap between those two numbers is usually the most useful thing you will learn about your own hydration.
When water alone is enough — and when it isn't
| Situation | Water alone | Add electrolytes |
|---|---|---|
| Under 60 min, cool indoor gym | Usually fine | Optional |
| 60–90 min, moderate sweat | Borderline | Helpful |
| Over 90 min, or hot and humid | Not ideal | Yes |
| Salty sweater, any hard session | Not ideal | Yes |
| Two-a-days or back-to-back sessions | Not ideal | Yes |
| Low-carb or keto eating | Often insufficient | Yes |
| Outdoor labor, long shifts, heat exposure | Not ideal | Yes |
The low-carbohydrate row surprises people. Lower carbohydrate intake reduces circulating insulin, and lower insulin increases sodium excretion by the kidneys — which is a large part of why the first weeks of keto come with fatigue, headaches, and cramping that a bit of salt often resolves.
The opposite mistake: too much plain water
Worth stating plainly, because hydration advice rarely does. Drinking large volumes of plain water far beyond your sweat losses can dilute blood sodium — exercise-associated hyponatremia. It is uncommon, but it is serious, and it mostly happens to people who drink to a rigid schedule rather than to thirst during long events.
Two practical guards: drink to thirst rather than to a number, and include sodium when sessions are long or hot rather than pouring in more plain water.
Timing: before, during, or after?
Timing is the least important variable here, so keep it simple:
- Before — useful if you are starting a hot or long session already behind on fluid, or training first thing after a night's dehydration.
- During — the priority for anything past about an hour, or anything in real heat. Sip rather than gulp.
- After — replaces what the session cost, and matters most before a second session in the same day.
Consistency beats optimization. The electrolyte drink you actually take daily is worth more than the perfectly timed one you skip.
What one scoop of MNRLZ replaces
| Per 1 scoop in 16–20 oz water | Amount | % DV |
|---|---|---|
| Sodium (Himalayan Pink Sea Salt) | 600 mg | 26% |
| Potassium (Potassium Chloride) | 444 mg | 9% |
| Magnesium (Di-Magnesium Malate) | 40 mg | 10% |
| Vitamin B12 (Methylcobalamin) | 9 mcg | 375% |
| Coconut Water Powder | 1,000 mg | — |
| Sugar | 0 g | — |
600 mg of sodium is aimed at the middle of the range — enough to matter for a real training session or a hot day, without the 1,000 mg+ load of an endurance-event formula that most people do not need daily. Zero sugar, stevia sweetened, third-party tested every batch, 30 servings per tub.
Related questions
Do electrolytes stop cramps?
Cramping is not fully understood and sodium is not a guaranteed fix — fatigue and neuromuscular factors play a role too. That said, cramping in long hot sessions in someone with visibly salty sweat is the scenario where sodium replacement is most plausibly worth trying.
Can you take electrolytes on rest days?
Yes. MNRLZ is built for daily use, and heat, travel, long shifts, caffeine, and low-carbohydrate eating all create losses that have nothing to do with training. Watch total sodium across your whole diet rather than the powder alone.
What should I check on the label?
See sugar-free electrolyte powder: what to look for, and methylcobalamin vs cyanocobalamin on why ingredient forms matter.
Test It On Your Own Sweat.
One free single-serving stick pack, shipped to US addresses. No credit card, no subscription.
Get a Free Sample See Pre-Order Packs