When people start intermittent fasting one question they have is if they can continue to drink coffee while intermittent fasting.

If you’re like me, then coffee is a daily part your day. So for me to give up coffee for even a  short amount of time would be extremely difficult and be honest I don’t think I’d want to do it.

So let’s look at the science of whether or not you can drink coffee while fasting.

Will black coffee break your fast?

Black coffee doesn’t have any calories in it, but in some people, the caffeine in coffee can raise their blood glucose and blood insulin levels temporarily, which are the two things we’re trying to avoid doing with our fasting. It appears that this effect is seen mainly in people of Asian ethnicity. The effect is caused by caffeine raising cortisol and epinephrine levels which lead the body to start making glucose. The effect also seems to be more common in people with a specific genetic variant which causes them to be slow metabolizers of caffeine.

This bump in blood sugar levels is one reason why the labs tell you not to drink coffee if you are getting fasting bloodwork done.

So its ok to drink black coffee while intermittent fasting.

Health benefits of coffee

However, being a regular coffee drinker may decrease the risk of developing diabetes according to this study. The study tracked over 100,000 men and women across three different studies (Nurses Health Studies I and II and the Health Professionals Follow-up Study) and found that people in the research studies the increased their daily coffee consumption by one cup a day actually decreased their risk of developing diabetes by about 11%. What was also surprising is that those people who decreased their coffee consumption by one cup a day actually increased their risk of developing diabetes by about 17%.

So even if there is a slight acute increase in blood glucose or insulin levels from the caffeine in coffee, we don’t see a long-term negative impact on our health.

Can you have your coffee with cream or sugar on a fast?

However, most people don’t drink your coffee black. Some add creamer or milk. Others add sugar or sweeteners.

The answer is, it depends on how dogmatic you want to be about fasting.

If we are only talking about nutritional intermittent fasting, we really want to avoid adding anything to our coffee that would either increase our blood sugar or cause insulin levels to rise.

If you’re adding a splash of heavy cream, which is mostly fat and very little sugar then you’re not going to see a noticeable change in your blood sugar. So that splash of heavy cream to your coffee won’t break your fast.

However, be careful if you’re getting your cream added at a coffee shop like Starbucks. Their “cream“ is actually half-and-half,  which is half cream and half milk. Milk does have some sugar in the form of lactose, and if you add enough half-n-half to your coffee, you may cause an increase in your blood sugar and that would break your fast. Adding in skim, 2%, or whole milk to your coffee would also potentially increase blood glucose levels from the sugar in milk.

So be careful of adding too much cream or milk to your coffee while intermittent fasting.

What about sugar and artificial sweeteners and nutritional sweeteners?

Regular table sugar (or sucrose) is going to have some impact on your blood glucose and insulin level, so sweetening your cup of java with regular sugar would break your fast.

Artificial sweeteners like saccharine might have some impact on blood glucose and insulin levels as well and there’s also a question about whether or not they alter the gut biome.

The other question you have to ask yourself is since we’re doing the fasting for health benefits, will the change in the gut biome from the artificial sweeteners negatively impact the health benefits were trying to obtain?

Sucralose (Splenda) may also raise your insulin levels by triggering the sweet-tasting receptors in your mouth,  so best to avoid adding these sweeteners to your cup of coffee.

Stevia doesn’t seem to impact either blood sugar or insulin levels, so Stevia would be one choice to sweeten your coffee if you don’t want to break your fast.

I typically recommend avoiding adding artificial or nutritional sweeteners except for Stevia to your coffee while intermittent fasting.

Adding ghee or butter or coconut oil or MCT oil to coffee while intermittent fasting

These higher fat products don’t have much in the way of added sugars and won’t have any impact on blood sugar or insulin levels. However, remember that we’re trying to restrict calories as well while intermittent fasting, so adding these calorically-dense foods could set back your weight loss goals.

The verdict: Can you drink coffee while intermittent fasting?

So use common sense when intermittent fasting. Black coffee or coffee with a splash of heavy cream or a couple of drops of Stevia won’t break your fast, but be careful about adding MCT or coconut oil since the added calories will slow your weight loss.

Check out our keto coffee recipe as well as our “Proffee” Keto coffee protein drink.