Sugar-Free Electrolytes vs Sports Drinks: Hydration Is Not Fuelling

They do two different jobs. A sugar-free electrolyte sachet supplies sodium and minerals with no energy; a sugary sports drink, a carbohydrate-electrolyte solution in the GB claims register's words, supplies 80 to 350 kcal a litre of fast sugar with sodium, and it is the only kind of drink the register lets say anything about water absorption or endurance.¹ Sodium does the salt job, carbohydrate does the energy job, and a long session can need both, from a sachet plus gels and food or from a sugared drink. Part of electrolytes for athletes in the Wellgard electrolyte guide.

Evidence at a glance

• Studies: the GB claims register and the retained annex; a 72-man drinks trial; a 12-man sodium trial; a sweat dataset of 506 athletes; a 488-runner marathon cohort; one review of carbohydrate intake.
• Largest single trial: 72 men, 13 drinks, urine collected for four hours after a litre of each.²
• Strongest measured outcome: after a litre, an oral rehydration solution left 1,038 g of urine against 1,337 g after water, and a sports drink was no different from water, in a trial funded by a hydration research institute whose advisory board the lead author chaired.²
• Not tested: no sugar-free electrolyte sachet has been tested for fluid retention or performance.

Sources checked on 17 October 2026.

What is a carbohydrate-electrolyte solution?

A sugared sports drink that meets four conditions. The retained annex to Regulation 432/2012 lets a drink say that carbohydrate-electrolyte solutions "enhance the absorption of water during physical exercise" and "contribute to the maintenance of endurance performance during prolonged endurance exercise" only when it provides 80 to 350 kcal a litre from carbohydrate, at least 75% of that energy from carbohydrates with a high glycaemic response (glucose, glucose polymers, sucrose), 20 to 50 mmol/L of sodium (460 to 1,150 mg/L) and an osmolality of 200 to 330 mOsm/kg.¹ Described by type: an isotonic sports drink is built to the definition; a corner-shop glucose drink has the sugar but about 26 mg of sodium per 100 ml, far below the band; a quarter teaspoon of salt in a litre of squash sits inside the sodium band and may or may not reach the energy line.³ Which drinks contain electrolytes has the per-serving table.

What can a sugar-free electrolyte label say about hydration?

Nothing that claims a hydration effect. A sugar-free sachet provides no carbohydrate energy, so it fails the first condition and sits outside the definition; sodium itself has no authorised claim on the register.¹ In March 2026 the Advertising Standards Authority upheld a complaint against a paid social-media advert for sugar-free electrolyte sachets (ruling A25-1315087, 18 March 2026): calling the product a way "to hydrate" was a specific health claim with no register entry, and "75% of people are chronically dehydrated" was treated as a claim to treat a disease.

What a sugar-free label may say is what its minerals do, each at 15% of its reference intake or more a serving: magnesium (56.25 mg) contributes to electrolyte balance and to normal muscle function; potassium (300 mg) contributes to normal muscle function and the maintenance of normal blood pressure; calcium (120 mg) contributes to normal muscle function.¹ That is not a smaller job than the sports drink's; it is a different one. The sachet is the salt; the fuel comes separately, and you choose how much.

Carbohydrate per hour: the fuelling question

Energy matters once a session runs past about an hour, and the amount rises with duration. A 2014 review puts it at a mouth rinse or small amounts for exercise of about an hour, up to about 60 g an hour from a single sugar for two to three hours, and about 90 g an hour from mixed sugars (glucose with fructose) for ultra-endurance events, with the carrier a liquid, gel or solid as you prefer; the advice does not scale with body weight.⁴ The 2016 joint position of the American College of Sports Medicine and two dietetic bodies says the same in outline and sends athletes to a registered dietitian for the personal plan.⁵ A 500 ml sports drink at the top of the register band carries about 44 g of sugar; sugar-free electrolytes carry none, by design.¹

Sodium per hour: the hydration question

Sodium matters once sweat does. In 506 athletes, sweat carried about 0.8 g of sodium a litre (range 0.4 to 1.6 g) at about 1.2 litres an hour, so an hour of hard sweating costs about a gram.⁶ A sports drink at 460 to 1,150 mg/L replaces roughly half to all of average sweat litre for litre; a sugar-free sachet does the same at whatever strength its label and mixing volume give (the per-litre method).^{1, 6} What the retention trials measured was drinks, not products: in 12 men dehydrated by 2%, a 61 mmol/L sodium drink left median urine of 260 ml over 7.5 hours against 493 ml for 23 mmol/L, and in the 72-man trial, funded by a hydration research institute whose advisory board the lead author chaired, a rehydration solution and milk were kept longer than water while a sports drink was not.^{2, 7} No sugar-free sachet was in either trial. Drink to thirst either way: at the 2002 Boston Marathon the type of drink was not associated with low blood sodium, weight gain was.⁸

Which do you need today?

Match the drink to the two jobs the session asks for.

Does sugar-free mean sweetener?

Usually, and the label has to say so. Under retained Regulation 1169/2011, Annex III, a food containing a sweetener carries "with sweetener(s)" beside its name, one with both sugar and sweetener says "with sugar(s) and sweetener(s)", and one with more than 10% added polyols says "excessive consumption may produce laxative effects".⁹ A drink with more than 150 mg of caffeine a litre carries a high-caffeine statement, and the NHS says no more than 200 mg of caffeine a day in pregnancy.^{9, 10} A sugar-free sachet also adds no energy, which is why most intermittent-fasting schemes allow it; do electrolytes break a fast? takes that question.

Who should be careful?

With either drink, the sodium counts towards the NHS 6 g of salt a day, and with high blood pressure, heart failure or kidney disease, or a medicine that holds sodium or potassium, ask a pharmacist or GP first.³ A sports drink's sugar counts towards the day too, and a sugar-free sachet is not an oral rehydration solution: with vomiting or diarrhoea the NHS route is a pharmacist's rehydration sachet, which carries glucose for a reason.¹¹

What we don't know

• No trial has tested a sugar-free electrolyte sachet for fluid retention or performance; the drink trials used rehydration solutions, milk, sports drinks and laboratory sodium drinks.
• No trial has compared a sachet-plus-gels strategy with a sports drink over the same event.
• The carbohydrate figures come from a review whose author worked at a sports-drink maker's research institute; the position statement is independent but gives ranges, not a single answer.^{4, 5}

Frequently asked questions

Can you take sugar-free electrolytes and a sports drink together?

Yes; add the sodium from both against your sweat and the 6 g, and the sugar from the drink against the hour's energy need.^{1, 3} Most people pick one for the salt job and gels or food for the fuel.

Do sugar-free electrolytes hydrate you better than water?

No trial has tested one. The trials that found a difference used an oral rehydration solution, milk or a laboratory sodium drink; a sports drink was no different from water over four hours.^{2, 7}

Is a sports drink an electrolyte drink?

Partly. An isotonic sports drink carries 460 to 1,150 mg/L of sodium by definition, inside the sweat range, with 40 to 175 kcal of sugar per 500 ml; a glucose drink from the corner shop carries sugar with very little sodium.^{1, 3}

Do sugar-free electrolytes break a fast?

They add no energy, so most intermittent-fasting schemes allow them; a sports drink is a food. Do electrolytes break a fast? has the detail.

Sources

1. Department of Health and Social Care. GB nutrition and health claims register; retained Regulation (EU) 432/2012 annex. gov.uk.
2. Maughan RJ, et al. Randomised crossover trial, 72 men, 13 drinks; funded by a hydration research institute whose advisory board the lead author chaired. Am J Clin Nutr 2016. PubMed 26702122.
3. NHS. Salt in your diet. Reviewed 17 April 2023 (overdue); checked 17 October 2026. nhs.uk. Glucose-drink sodium: Public Health England, CoFID 2021. gov.uk.
4. Jeukendrup A. Narrative review; author at a sports-drink-maker research institute. Sports Med 2014. PubMed 24791914.
5. Thomas DT, Erdman KA, Burke LM. Joint position statement of three professional bodies. Med Sci Sports Exerc 2016. PubMed 26891166.
6. Baker LB, et al. Observational, 506 athletes (404 male); sports-drink-maker research institute. J Sports Sci 2016. PubMed 26070030.
7. Shirreffs SM, et al. Controlled trial, 12 men, two sodium drinks at four volumes; funding not checked. Med Sci Sports Exerc 1996. PubMed 8897383.
8. Almond CS, et al. Cohort, 488 marathon runners tested; publicly funded. N Engl J Med 2005. PubMed 15829535.
9. Retained Regulation (EU) 1169/2011, Annex III (sweetener, polyol and caffeine statements). legislation.gov.uk.
10. NHS. Water, drinks and hydration. Reviewed 17 May 2023 (overdue); checked 17 October 2026. nhs.uk.
11. NHS. Dehydration. Reviewed 1 May 2026; checked 17 October 2026. nhs.uk.

General information, not medical advice. With high blood pressure, heart failure, kidney disease or diabetes, or a medicine that affects sodium or potassium, ask a pharmacist or your GP before using any electrolyte or sports drink regularly.

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