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What to drink when fasting on keto

So you’ve decided to give intermittent fasting a go on keto. However, are you confused about what you can or can’t drink while fasting on keto? It isn’t just water there are a few items you can have.

What is intermittent fasting?

intermittent fasting on keto - eating windows

If you already know what it is, then skip to the next section!

Intermittent fasting is where you alternate between periods of eating and not eating (fasting). It isn’t a new thing and has been practised for thousands of years throughout many cultures.

There are many fasting patterns that people like to adhere to, such as:

  • 16:8 – where your eating window is 8 hours and you fast for the other 16 hours
  • 18:6 – where your eating window is 6 hours and you fast for the other 18 hours
  • OMAD – eat one meal a day in one two hour window and fast for the rest
  • 24 or 48 – where you fast for more than a day at a time, usually once or twice a week

Some people like to follow these kinds of patterns regularly, whereas others will practice them every for 5 days a week (working week) or once every month.

As for the benefits, your body undergoes some metabolic changes during fasting. The chief among them is that you will enter ketosis, where your fat reserves are used for energy. Other benefits include Insulin levels decrease and promote autophagy – a bodily process that helps to sheds itself of damaged or harmful cells.

Drinks to consume while fasting on keto

Of course, fasting means that you shouldn’t be eating anything. However, you can still drink liquids that don’t contain many (or any) calories and sweeteners.

That being said, some experts say that small amounts of low-carb, high-fat products will probably not break a fast. In our case, we’re not going to include them.

Here are some beverages you can drink while fasting on keto:

  • Water – just plain old water (plain or carbonated) is the best drink for fasting on keto. Zero calories and will keep you hydrated.
  • Coffee – black with no milk or sweetener. Caffiene will also keep you alert and help to surpress your appetite.
  • Tea – same as coffe, black with no milk or sweetener.
  • Apple cider vinegar -1tsp diluted with water can help to prevent cravings.
  • Bone broth – can help to keep you electrolytes in balance which can be washed away when only drinking water.

Some experts say that you should stay away from sources of caffeine during fasting as it affects your liver function and speeds up your metabolism. However, most say it’s fine and won’t interfere with fasting as it doesn’t contain any calories.

What about sweeteners while fasting?

consuming sweeteners while fasting on keto
Coffee, Milk & Sugar” by shixugang

Honestly, it’s probably best to avoid sweeteners while fasting on keto as they may spike your insulin levels and break your fast. However, if you can’t stomach plain black coffee or tea then pick one that is low on G.I (glycaemic index) scale.

Check out our article on the best sweeteners to use in tea for sweetener recommendations.

Other drinks such as diet or zero carbonated drinks like coke and lemonade should generally be avoided for the reason stated above. Although, many people do consume these while fasting and have not experienced any issues or cravings (your mileage may vary).


When intermittent fasting on keto you can drink pretty much anything that is zero calories and doesn’t spike your insulin levels. Some of the best options include water, coffee and tea.

Everyone is different, so see what works for you. I’ve found that water and coffee are my go to drinks while fasting and I don’t experience any negative effects even with drinking multiple cups of the black juice a day.

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