Can I Have Half & Half in Coffee When Fasting? We Ran the Tests!

half & half break a fast- Feature Picture (11)

Can I Have Half & Half in Coffee When Fasting? We Ran the Tests!

We ran a test to discover if adding half & half to our morning coffee will break a fast.

In this post, we share the results along with our testing methods and materials.

Can I Have Half & Half in Coffee When Fasting? [Video]

We tested our blood glucose and ketones after drinking coffee with Half & Half to see if it would kick us out of fat-burning mode and interfere with our intermittent fast.
Here are our results!


If you follow our channel, you know we do a lot of testing.

We have tested a bunch of different things in our morning coffee to see how they affect our intermittent fast. (Check out our other tests at the bottom of this post)

One we have not tested at this point is half & half.

Methods and Materials

So here is what we did.

  1. We got up bright and early in the morning
  2. We pricked our fingers to get a baseline test of our blood glucose and ketones
  3. We quickly drank down one cup of coffee with one serving of half & half (2 Tablespoons or 30ml)
  4. We retested our blood at 30 minutes, 60 minutes, and 120 minutes
half and half in coffee testing if it will break a fast


During this time:

  • We did not have any extra coffee
  • We did not have any supplements
  • We did not do any exercise

Addressing Our Viewer’s Concerns


So we have run many of these tests, and we have gotten many comments.

So we are going to go through some of the most common comments that we get to nip them in the bud, hopefully.

Comment #1

“…, but you are taking in calories when you have half & half?”



It is true. You are taking in calories, so your body will need to utilize those.

Comment #2


“…, but isn’t that going to stop autophagy?”



Probably for a little bit.

Comment #3


“…, but that’s not a double-blind random controlled test.”



No, it’s not.


We are in our kitchen, but we are working as hard as we can to control a lot of the variables.


What We Are Looking To Test: Fat-Burning State

Our hypothesis is:

We can have half & half in our coffee while we are intermittent fasting if it does not push us out of fat-burning mode.

What would push us out of fat-burning mode?


Any increase in insulin.


Right, and why are we not testing insulin?


Because they do not have, at this point, an at-home, in-kitchen, non-double-blind, random-controlled trial kit to test insulin levels.


Right, so we are testing our blood glucose and ketones to get an idea of what our bodies might be doing with insulin.

So, a favorable result, or what we are looking for, is that our blood glucose will not rise significantly and that our ketones will not drop significantly.



Right. Blood glucose and ketone levels are just a proxy for what is actually going on with insulin inside the body.


So here is what happened when we put half-and-half in our coffee.

Will Half & Half Break A Fast?: Ketone Results


Here are our results.

At zero minutes, Becky’s ketones were 0.9 mmol/L, at 30 minutes they were 1.1 mmol/L, at 60 minutes they were 0.9 mmol/L, and at 120 minutes they were 1.1 mmol/L.

My ketones at zero minutes were 0.2 mmol/L, at 30 minutes it was 0.2 mmol/L, at 60 minutes it was 0.1 mmol/L, and at 120 minutes it was 0.2 mmol/L.

Half & Half Break A Fast -Our-Ketones-Half-Half


So from that, we see that our ketones held steady over the two hours of testing that we did.

Of course, we should throw in that, yes, Keith’s ketones were 0.2 mmol/L to start.

You had what? Twelve carbs yesterday in preparation for the test?




Also, you typically eat a ketogenic diet. So, you would think his ketones would be higher.

Well, this has been an ongoing problem for Keith. In Fact, we have addressed that Keith’s morning ketones are often quite low, and our theories why in a past video.


It’s still frustrating for me, but that’s the way it is.


However, the takeaway is that half & half did not significantly raise or lower our ketones.

So, what did it do to our blood glucose?

Will Half & Half Break A Fast?: Glucose Results


Becky’s glucose at baseline was 86 mg/dL, at 30 minutes it was 88 mg/dL, at 60 minutes it was 70 mg/dL, and at 120 minutes it was back to 88 mg/dL.

Now my glucose at the zero minutes baseline was 96 mg/dL, at 30 minutes it went up slightly to 103 mg/dL, at 60 minutes it was back to 95 mg/dL, and at 120 minutes it was up slightly to 102 mg/dL.

Half & Half Break A Fast - Our-Glucose-Half-Half

Those results are what we would consider an insignificant increase based on just the accuracy rate of the meter. The accuracy of that alone can make a 10-point difference.

Conclusion: Will Half & Half Break a Fast?


Yeah, so there too, we did not have a significant change in our glucose after putting half & half in our coffee.

Conclusion: Half & Half In Coffee

We would say, after our small kitchen test, that we feel comfortable having a serving of half & half cream in our morning coffee. We do not believe it will break our fast.


We should mention, that is one cup of coffee with one serving (2 Tablespoons/30ml) of half & half cream over a two hour period.

If you are having multiple cups of coffee, and you are pouring the half & half cream into your coffee each time, the result could be different.


Yeah, so keep that in mind.

Also, Keith alluded to heavy cream. We did test heavy cream in our coffee, and, Spoiler Alert, We had very similar results to half & half.

Thanks so much for reading. We hope this helps you with your intermittent fasting.

Make sure you subscribe to our YouTube channel for more testing videos in the future!

What Breaks a Fast? Our Other Tests

About the Authors

Dr. Becky Gillaspy, DC graduated Summa Cum Laude with research honors from Palmer College of Chiropractic in 1991.

Dr. Keith Gillaspy, DC, CFMP grew up in central Nebraska and earned his Doctor of Chiropractic in 1991 from Palmer College of Chiropractic in Davenport, Iowa. 

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