Drinks · ~0 kcal per can (355 ml)
Does sparkling water break a fast?
No. Plain sparkling water has 0 kcal, no sugar and no sweetener, so it is safe for every fasting goal. Tonic water is a sweet drink and breaks a fast.
The answer for each goal
Weight loss
SafeAutophagy
SafeGut rest
SafeBlood sugar
SafePlain sparkling water, also sold as soda water, seltzer or club soda, is water with carbon dioxide added. A 355 ml (12 fl oz) can has 0 kcal, no sugar and no sweetener. On the four goals this site uses to sort answers, plain sparkling water is safe for weight loss, blood sugar, autophagy and gut rest.
Tonic water looks the same in the glass but is a sweetened drink. Regular tonic has about 34 kcal and 9 g of sugar per 100 ml. A 355 ml can holds about 124 kcal and 32 g of sugar, which breaks a fast for every goal. Regular lemon-lime soda is higher again, at about 41 kcal and 10 g of sugar per 100 ml. Diet tonic made with a non-sugar sweetener sits in the grey area with other sweetened drinks, such as diet soda.
Flavoured sparkling water depends on what is in the can. A flavour essence with no sugar and no sweetener keeps the drink safe. A sweetener such as sucralose or stevia makes the drink a grey area for autophagy and blood sugar. On this site's rule for sweet tastes, weight loss becomes grey too. Sugar or fruit juice on the ingredients list means the drink breaks a fast.
Fizzy water flavoured with fruit or lemon can wear tooth enamel. Official dental advice is to keep carbonated and acidic drinks to meal times, which is harder during a long fast. If you sip flavoured sparkling water through the day, drinking it through a straw is one option, and don't brush your teeth straight after.
Watch out
Tonic water is a different drink from soda water. A 355 ml can of regular tonic has about 124 kcal and 32 g of sugar, so it breaks a fast.
Questions people ask
What zero-calorie drinks can I have while intermittent fasting?
Plain water, plain sparkling water, black coffee and plain black, green or herbal tea have 0 to about 2 kcal a cup and no sugar. Drinks made with zero-calorie sweeteners, such as diet soda, are a grey area for weight loss, autophagy and blood sugar.
Does flavoured sparkling water break a fast?
Not if the only flavouring is an essence with no sugar or sweetener. Versions with a sweetener are a grey area, and any with sugar or fruit juice break a fast. The ingredients list tells you which kind you have.
Are zero-sugar drinks OK while intermittent fasting?
Zero sugar does not always mean zero sweetener. A drink with no sugar and no sweetener is safe for every goal. A drink sweetened with sucralose, aspartame or stevia is a grey area for weight loss, autophagy and blood sugar.
Related answers
Herbal tea
No. Plain herbal teas such as peppermint, chamomile and hibiscus have 0 to 2 kcal a cup, w…
Diet soda
A can of diet soda has 0 to about 7 kcal, too few to matter much for weight loss. Its swee…
Lemon water
A squeeze of lemon adds about 1 kcal, so lemon water is safe for weight loss, blood sugar …
Unsweetened electrolytes
No. Salt, magnesium and unsweetened electrolyte mixes have no meaningful calories and are …