Does Coffee Break A Fast?

If you like coffee as much as I do, but you don’t want to mess up your intermittent fasting, or if you have the same question – Does coffee break a fast? Then this Blog post is for you!

I really love coffee. I’m probably addicted to coffee – I don’t know… I’ve not tried cutting down for a long time. Morning coffee is a ritual for me… I know exactly how I like my coffee. The only thing I’m able to do before drinking coffee in the morning is …. Ummm… make the coffee… oh… and let the dog out!

In this post I’m going to be answering one question I get asked most about with intermittent fasting.

Can I drink black coffee when fasting?

Is adding milk or cream going to break the fast?

Is it true that as long as you don’t drink more than 50 calories you don’t break your fast?

Table of Contents

What do we want to be happening?

In this post I am talking about fasting for weight loss, and nothing to do with longevity which is a whole different subject.

We need;

  • Fasting blood glucose levels to be normal
  • Fasting Insulin levels to be low
  • Fasting glucagon to be raised (it’s effect is opposite to insulin)
  • Fat burning / Ketone Production to be encouraged

Is drinking coffee going to disrupt this?

Is it going to disrupt fat burning within the body?

Black Coffee

Also includes green tea / black tea / anything without milk.

Not really. It’s pretty much 0 fat / 0 protein / 0 carb and is literally no calories.

It’s just basically caffeinated, hot, brown water, with a few other things in it that make it taste really nice.

does coffee break a fast

What about cream or milk?

One of the most common pieces of advice on the internet is that it’s ok to drink something as long as it’s 50 Calories Or Less.

You’ll find many people talking about 50 calories or less. I don’t think this is particularly useful.

50 Calories of Cream – approx 1 tablespoon (0.5g net carbs) basically pure fat – very little carbohydrate content.

50 Calories of Milk – approx 8 tablespoons – remember that lactose in milk is a sugar. Approx 6grams of carbohydrate. Who has 8 tablespoons of milk in their coffee? Well.. just remember that a late is espresso + entirely milk. Full fat milk has less carbohydrate for the same amount of volume as does low-fat versions.

50 Calories of Pure Sugar? That would be just over 3 teaspoons of sugar you’re allowed.

So looking at it purely in terms of calories isn’t particularly useful! Clearly, these are all going to have very different metabolic effects on the body.

Other Benefits Of Coffee

Coffee is an appetite suppressant?

If this is true then this is great for people who are fasting as a way of keeping hunger at bay! But sorry, no actual evidence that this is true. However, if it works for you… great!


Another old wives tale is that coffee is a diuretic. Whilst this is slightly true, the overall effect doesn’t overpower the fact that you’re drinking lots of fluid with it. Overall result. Hydration.
Ok, now for the good stuff…

Coffee Stimulates Ketone Production

A study has shown that … Caffeine given at breakfast significantly stimulated ketone production in a dose-dependent manner.

Don’t overdo it…

Excessive coffee has been shown to raise fasting blood glucose and reduce insulin sensitivity.

In Summary

Ideally, drink black coffee only

Black coffee / Green Tea / Black tea – basically something without milk.

Learning to drink black coffee is much like learning to take tea or coffee without sugar. It might taste a bit weird at first, but you quickly get used to it!

If you don’t like black coffee - sure have some milk or cream

1 tablespoon of cream in your coffee is unlikely to significantly disrupt your fast. Just remember it’s not completely without carbohydrate content, so if you’re actually having 3 teaspoons in your coffee / and you’re having 4 of those in a day… you’ll need to account for those.

A small amount of milk in your coffee also isn’t likely to disrupt your fast. Lactose in milk is sugar.

A latte or cappuccino made entirely with milk… will.

Green tea is a really good option.

Drink black tea with a small amount of milk as is needed for you to enjoy it!