Home/Guides/Do electrolytes actually matter?
Sports-drink ads and wellness influencers agree on one thing: skip the electrolytes and you’re basically dehydrated, every single day. Mostly, you’re not. Electrolytes earn their keep during heavy sweat, hard exercise, and illness, because sodium and potassium help your body hold onto the water you drink instead of losing it. On a normal day with normal meals, you already have plenty.
Where the electrolyte-every-day idea comes from
The pitch is everywhere: hydration tablets, flavored powders, “add this packet daily or you’re basically dehydrated.” It builds on one real fact. Heavy sweat during long, hard exercise genuinely drains sodium and potassium, and endurance athletes benefit from replacing it.
Somewhere between the lab and the checkout aisle, that narrow claim got stretched thin. “Athletes training for hours need electrolytes” turned into “everyone needs electrolytes, every day,” aimed at people sweating through a commute, not a marathon.
What electrolytes actually do in your body
Electrolytes, mainly sodium and potassium, aren’t a hydration multiplier on their own. Their job is retention: sodium signals your kidneys to hold onto water rather than pass it straight through as urine. Drink plain water without replacing lost sodium, and there’s a ceiling on how much your body keeps, no matter how much you pour in.
Electrolytes don’t add hydrating power to water; they help your body hold onto the water it already has.
That’s the mechanism behind why oral rehydration solution (ORS) and milk, both naturally rich in sodium and potassium, out-hydrate plain water in lab testing (also true of milk specifically). It’s also why a large volume of plain water, with nothing helping your body retain it, can pass through faster than you’d expect.
When electrolytes genuinely help
The clearest demonstration is a small, pointed 1996 study. Shirreffs and colleagues dehydrated 12 men by about 2% of body mass through cycling, a real level of sweat loss, then had them rehydrate with drinks carrying different amounts of sodium. Drinking more than they’d sweated out wasn’t enough by itself: without adequate sodium, the surplus fluid was simply excreted as urine rather than kept. Add sodium to the same volume, and it stayed in the body.
That’s the same mechanism behind the Beverage Hydration Index (BHI), a 2016 trial ranking 13 drinks by how long they kept 72 men hydrated against a plain-water baseline.
| Drink | Hydration vs water |
|---|---|
| Skim milk | 1.58 |
| Oral rehydration solution | 1.54 |
| Full-fat milk | 1.50 |
| Water | 1.00 (benchmark) |
| Sports drink | ≈ water (not significant) |
Oral rehydration solution, essentially water with a deliberately high sodium dose, topped the ranking. A common sports drink, tested in the same trial, scored no better than water at all (a finding we’ve flagged before): proof that “contains electrolytes” on a label isn’t automatically enough. The dose has to match the loss.
How to tell if today needs electrolytes
Our honest answer: check your losses, not the label. If you’ve sweated through a shirt, trained hard for a long session, or you’re fighting vomiting or diarrhea, replacing sodium and potassium alongside water is a real, evidence-backed idea. If your day was a desk, air conditioning, and three normal meals, you’ve already had your electrolytes with lunch.
That’s why Brim doesn’t credit a bottle of sports drink or coconut water as a hydration bonus (Premium). Both log a shade below plain water, matching the trial finding above that a mainstream sports drink scored no better than water, and accounting for the sugar riding along with the electrolytes. True oral rehydration solution, dosed for real fluid loss, is the exception the evidence actually supports, not the bottle in the gym fridge.
| Drink | Brim hydration credit |
|---|---|
| Water | 100% (benchmark) |
| Sports drink | 96% (Premium) |
| Coconut water | 90% (Premium) |
You can look up any drink’s exact credit in the BHI Hydration Index Lookup.
When you probably don’t need them
For most people on most days, the case for a daily electrolyte habit is thin. You’re not draining sodium through sweat if you spent the day sitting, and ordinary meals, bread, cheese, soup, most anything processed, already carry sodium most people aren’t short on. Add a normal water habit on top, and there’s no gap left for a powder to fill.
The honest checklist
Electrolytes earn their place when the loss is real
Heavy, visible sweat over a long session, or back-to-back sessions in the heat.
Vomiting or diarrhea, which drain sodium and potassium fast, not just water.
A hard endurance effort well past the length of a casual workout.
Outside those, a normal day of meals and water already covers it.
Key takeaways
Electrolytes don’t add hydrating power on their own; they help your body hold onto the water you already drank.
A 1996 trial (Shirreffs et al.) shows it directly: without sodium, drinking more than you sweated out was simply excreted, not retained.
A mainstream sports drink scored no better than water in the 2016 BHI trial; true oral rehydration solution, dosed for real loss, is what actually pulls ahead.
Reach for electrolytes during heavy sweat, hard endurance efforts, or illness. Brim credits sports drinks and coconut water close to water, not above it (Premium).
Frequently asked
Do I need electrolytes every day?
No, not if you’re eating normal meals and not sweating heavily. Ordinary food already supplies sodium and potassium; a daily powder or tablet is built for real fluid loss, not an average desk day.
When do electrolytes actually matter?
During heavy sweat, hard endurance exercise, or illness like vomiting or diarrhea. A 1996 trial found that after sweat-loss dehydration, extra fluid without sodium was simply excreted rather than retained.
Are sports drinks better than water for hydration?
Not necessarily. In the 2016 Beverage Hydration Index trial, a mainstream sports drink scored no differently from water, while oral rehydration solution, dosed with far more sodium, scored well above it.
What’s the difference between a sports drink and oral rehydration solution?
ORS is dosed specifically for rehydration, with a high, deliberate sodium content (55 mmol per liter in the trial above). Many consumer sports drinks carry less sodium and more sugar, built for taste, not fluid retention.
How does Brim credit electrolyte drinks?
Sports drinks and coconut water log at 96% and 90% of water (Premium), close to water rather than above it, matching the finding that a mainstream sports drink doesn’t out-hydrate plain water.
Keep reading
Sources
- 1.Maughan et al., “A randomized trial to assess the potential of different beverages to affect hydration status” (Beverage Hydration Index), Am. J. Clin. Nutr. (2016)
- 2.Shirreffs, Taylor, Leiper & Maughan, “Post-exercise rehydration in man: effects of volume consumed and drink sodium content,” Medicine & Science in Sports & Exercise (1996)
