Electrolyte drinks have gone from something marathon runners used to a staple in every gym bag. But do you actually need one, or is it just expensive flavoured water?
The honest answer: it depends on how long you train, how much you sweat, and what else you're eating. For some people electrolytes make a real difference to performance and how they feel. For others, water and a normal diet cover everything. This guide will help you work out which camp you're in.
What are electrolytes?
Electrolytes are minerals that carry an electrical charge when dissolved in body fluids. The main ones are:
- Sodium: the big one. It controls fluid balance and is the electrolyte you lose most of in sweat.
- Potassium: works alongside sodium to manage fluid inside your cells and supports muscle contraction.
- Magnesium: involved in muscle and nerve function and energy production.
- Calcium: needed for muscle contraction and nerve signalling.
- Chloride: pairs with sodium (as in table salt) to help regulate fluid balance.
Together they help you hold onto the water you drink, keep your muscles contracting properly and keep your nerves firing. When you sweat, you lose water and electrolytes, mostly sodium.
Why water alone isn't always enough
Sweat isn't just water. Depending on the person, a litre of sweat can contain roughly 0.5g to 2g of sodium, and some people (the ones with white salt marks on their t-shirts) lose a lot more than others.
If you sweat heavily for a long time and only replace the water, you dilute the sodium left in your blood. In mild cases that shows up as fatigue, headaches and feeling flat. In extreme cases, usually during very long endurance events, it can lead to a dangerous condition called hyponatraemia. Adding sodium to your fluids also helps your body retain what you drink instead of passing straight through it.
When you probably don't need electrolytes
Plenty of people are using electrolyte drinks when water would do the job just as well. You're unlikely to need them if:
- Your session lasts under about an hour
- You're training in a cool, air-conditioned gym and don't sweat much
- You eat regular meals with a normal amount of salt
- You're doing a typical weights session with long rest periods
A standard UK diet usually contains plenty of sodium, and your next meal will replace what you lost in a short session. That said, if you simply drink more when your water has some flavour, a low-sugar electrolyte drink is still a perfectly good way to hit your fluid intake.
When electrolytes really help
- Long sessions: continuous training of 60 to 90 minutes or more, such as running, cycling, rowing, HYROX, football or combat sports.
- Heavy sweating: hot conditions, summer training, hot yoga or saunas, or if you're naturally a heavy or salty sweater.
- Training twice a day: less time to rehydrate and replace sodium between sessions.
- Low-carb or keto diets: these increase sodium and water loss, which is part of why people feel rough in the first week or two.
- Weight-class sports and physique prep: where fluid and sodium intake are being manipulated and need managing carefully.
- Illness: vomiting or diarrhoea causes significant fluid and electrolyte losses. In this case a proper oral rehydration solution from a pharmacy is the right choice. Speak to a pharmacist or GP if symptoms are severe or last more than a day or two.
Signs you might be low on fluids or electrolytes
- Dark yellow urine or not needing the toilet for hours
- Headaches during or after training
- Unusual fatigue or feeling flat mid-session
- Dizziness when standing up
- Muscle cramps (the causes of cramp are debated, but heavy sweat loss can be a factor for some people)
- White, salty residue on your clothing or skin after training
How to work out how much you lose
A simple sweat test gives you a useful starting point:
- Weigh yourself before training, with minimal clothing.
- Train as normal, noting how much you drink.
- Towel off and weigh yourself again afterwards.
Each kilogram lost is roughly a litre of fluid. Aim to drink around 1.25 to 1.5 times that amount over the next few hours, since you'll keep losing some through urine. If you regularly lose more than about 2% of your body weight in a session, that's a strong sign you'd benefit from drinking more during training, with electrolytes added.
How to choose an electrolyte drink
- Look at the sodium content: it's the electrolyte that matters most for heavy sweaters, and some products contain very little.
- Check the sugar: some sugar helps during long endurance work, but for everyday hydration or gym sessions a low or zero-sugar option is usually better.
- Extras: ingredients like taurine, coconut water extracts (such as Cocomineral) or added vitamins can round out a formula.
- Taste: the best hydration drink is the one you'll actually drink, so flavour matters more than people admit.
Here are a few we stock:
- TWP Hydra-Plenish: Cocomineral, taurine, Himalayan pink salt and an electrolyte blend, in seven flavours
- Conteh Sports Hydra Flow: a Cocomineral-based formula that works well as an everyday hydration drink
- Per4m Hydrate: Cocomineral plus taurine, in a wide range of flavours
- DNA Sports Hydra 1 and Combat Fuel Hydrate or Die: good options for longer, sweatier sessions
- HR Labs HydroEAA: if you want essential amino acids and electrolytes in one intra-workout drink
Can you have too many electrolytes?
For most healthy people, an electrolyte drink or two a day alongside a normal diet is fine. But more isn't always better. The NHS recommends adults keep salt intake to no more than 6g a day, and sodium from hydration drinks counts towards that. If you have high blood pressure, kidney problems or heart conditions, or you're on medication that affects fluid or sodium balance, speak to your doctor before using electrolyte supplements regularly.
The bottom line
If you're doing a 45-minute weights session in a cool gym and eating normally, water is all you need. If you're training for longer, sweating heavily, training twice a day or working out in the heat, adding electrolytes can help you stay hydrated, feel better and perform better.
Not sure which hydration product suits you? Message the team and we'll point you in the right direction.
Related reading from The Insight Scoop
- Why Recovery Matters More Than Your Workout (And How to Actually Do It Right)
- EAAs vs BCAAs: Do You Need Both?
- Complete Pre-Workout Guide 2026: How to Choose the Right Formula
This article is for general information only and isn't medical advice. If you have a medical condition or take medication, speak to your GP before changing your supplement routine.