For a 5k after a carbohydrate-based breakfast or snack, choose water for fluid rather than treating a sparkling mixer as running fuel; the UK Sports Institute says a sports drink is probably unnecessary after that kind of breakfast. If you have missed breakfast, a carbohydrate drink may be an option, while plain sparkling water offers fizz if you dislike still water. Choose a tonic for its flavour outside the run, not as a substitute for a pre-run food or drink you know suits you.
If you have had a carbohydrate-based breakfast or snack, your drink choice can focus on fluid. The UK Sports Institute says you probably will not need a sports drink after a carbohydrate-based breakfast; the NHS suggests sparkling water if you dislike plain water.
If eating before a run is difficult, the UK Sports Institute says drinking some carbohydrate could be an option. Choose a carbohydrate drink or food that suits your routine rather than assuming a tonic mixer serves the same purpose.
If flavour is the reason for buying a mixer, compare its sugars per 100ml and the amount you plan to drink. A light tonic can still contain sugar, so its label matters more than the word ‘light’.
Decide whether the drink is for fluid during or after the run, carbohydrate before it, or simply a fizzy flavour afterwards.
| Priority | What to check | Your needs |
|---|---|---|
| Fluid | For fluid lost through sweating, the NHS recommends water. It also suggests sparkling water if you dislike plain water. | I have eaten beforehand and mainly want a drink for fluid; fizz would make water more appealing. |
| Pre-run carbohydrate | If breakfast was missed, consider whether a carbohydrate food or drink suits you. The UK Sports Institute says drinking carbohydrate could be an option when you have not had time to eat. | On mornings when I cannot eat before running, I want to choose carbohydrate deliberately rather than rely on the sweetness of a mixer. |
| Fizzy flavour | For a tonic you plan to drink outside the run, compare sugars per 100ml and the container size. Check whether a ‘light’ variant actually contains sugar. | I want a fizzy soft drink after my run, but I am choosing it for taste rather than running fuel. |
Sweetness alone does not tell you whether a drink meets your pre-run needs. The UK Sports Institute says a sports drink is probably unnecessary after a carbohydrate-based breakfast, while Fever-Tree and Fentimans describe their tonic waters as mixers for spirits.
Choose water when you mainly need fluid. If you have missed breakfast, consider a carbohydrate food or drink separately from your choice of mixer.
Fentimans lists 3.4g sugars per 100ml for Naturally Light Tonic Water, compared with 4.4g per 100ml for its Premium Indian Tonic Water. ‘Light’ does not, by itself, mean no sugar.
Read the sugars figure per 100ml on the exact drink you are buying and consider how much is in the container.
A new pre-run choice may not suit your usual eating and drinking routine.
Try your intended food or drink during an ordinary training run before relying on it for a target 5k.
These brand ranges provide examples of tonic-water choices; their inclusion does not make tonic a running-fuel product.
Fever-Tree describes its Premium Indian Tonic Water as a mixer for gin, vodka and fortified wines. It also offers a Refreshingly Light Indian tonic.
Fentimans offers Premium Indian Tonic Water and Naturally Light Tonic Water.
Britvic lists mixers alongside other drinks in its wider portfolio, including Aqua Libra sparkling water and Gatorade sports drinks.
These options cover sparkling water for a fluid-focused choice and tonic water for a fizzy drink outside the run. Neither should be chosen in place of a deliberate pre-run carbohydrate option when you need one.
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A sparkling-water option if you want fizz while choosing a drink for fluid rather than a tonic mixer. If you have missed breakfast and want carbohydrate before running, make that a separate food or drink choice.
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A tonic-water option when you want a fizzy mixer after the run or as a social soft drink. Check the pack’s nutrition and ingredients if those affect your choice; do not treat ‘slimline’ as a description of its suitability for pre-run fuel.
Do not choose tonic water on the assumption that it serves as a sports drink. The UK Sports Institute says drinking carbohydrate could be an option if you have not eaten before a run, but that a sports drink is probably unnecessary after a carbohydrate-based breakfast. Fever-Tree and Fentimans present their tonic waters as spirit mixers.
Yes, if you prefer it. The NHS recommends water to replace fluid lost through sweating and suggests sparkling water for people who dislike plain water. If you need carbohydrate before your run because you have missed breakfast, consider that need separately.
Not necessarily. Fentimans lists 3.4g sugars per 100ml for Naturally Light Tonic Water and 4.4g per 100ml for its Premium Indian Tonic Water. Check the nutrition label of the exact tonic and pack size you intend to buy.