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Let me introduce myself. My name is Mark Sisson. I’m 63 years young. I live and work in Malibu, California. In a past life I was a professional marathoner and triathlete. Now my life goal is to help 100 million people get healthy. I started this blog in 2006 to empower people to take full responsibility for their own health and enjoyment of life by investigating, discussing, and critically rethinking everything we’ve assumed to be true about health and wellness...

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April 24, 2018

Does Coffee Break an Intermittent Fast?

By Mark Sisson
73 Comments

Coffee Fast InlineThis has got to be one of the most frequent questions I see:

“Does coffee break a fast?”

Let’s answer.

To begin with, I’ll make the case that you shouldn’t worry too much about this stuff. That you’re even willing and able to go without a meal or snack for 12-24 hours places you in rarefied company. That’s 95th percentile stuff. You’re ahead of the game simply by being open to the idea of not eating every hour. Take heart in that. Some coffee with cream midway through doesn’t take away from what you’re accomplishing.

But I know you guys, and I know you love the minutiae. I know it because I love it, too. It’s fun, even if it gets us into trouble sometimes. So let’s dig right in.

First, does black coffee break a fast?

Put another way.. Does coffee interfere with the benefits we’re seeking from a fast? Depends on the benefits you’re seeking (and what you put in the coffee).

Let’s look at some of the most common benefits first and if/how coffee affects them.

Common Benefits of Fasting: Does Coffee Help/Hinder?

Ketosis

Fasting is a quick and easy (or simple) way to get into ketosis. You have little choice in the matter. Since you’re not eating anything, and your body requires energy, you break down body fat for energy. And because you’ve only got fat “coming in,” you’ll quickly start generating ketone bodies. If coffee stops ketosis, it’s probably breaking the fast.

A recent study found that taking caffeine acutely upregulates ketosis in humans.

Fat Burning

Fat-burning is another important aspect of fasting. Since we’ve already shown that coffee increases ketosis, I think it’s pretty obvious that coffee also increases fat mobilization and burning.

Insulin Sensitivity

Over the long term, fasting is an effective way to improve insulin sensitivity and glucose tolerance. Most things that make you better at burning fat and expending, rather than storing, energy—like exercise, low-carb diets, weight loss in general—tend to improve insulin sensitivity over time. But the sometimes counterintuitive piece to all this is that in the short term, fasting can reduce insulin sensitivity. This is a physiological measure the body takes to preserve what little glucose remains for the brain. All the other tissues become insulin resistant so that the parts of the brain that can’t run on ketones and require glucose get enough of the latter to function.

Coffee has a similar effect. Acutely, it reduces insulin sensitivity and glucose tolerance (so don’t eat pastries with your coffee). Over the long term, it improves insulin sensitivity and glucose tolerance; many studies find that the more coffee you drink, the lower your risk of type 2 diabetes.

Autophagy

Cellular cleanup. Pruning. Entropy dictates that all things are constantly speeding toward disorder. Things fall apart, in other words. That applies to our cells and the tissues they comprise, too. But because we are biological beings rather than inert objects, we can respond to and resist the descent into disorder. Autophagy is one of the ways in which we keep our cells healthy and maintained, pruned, and trimmed of damaged bits. Fasting is one of the best ways to induce autophagy. It’s one of fasting’s major selling points. If coffee destroys autophagy, that’d be a big mark against coffee and a sure sign it’s breaking the fast.

Good thing coffee doesn’t appear to hamper autophagy. At least in mice, both caffeinated and decaffeinated coffee induce autophagy in the liver, muscle tissue, and heart.

AMPK

Adenosine monophosphate-activated protein kinase, or AMPK, is an enzyme that inhibits fat storage and promotes fat burning. It activates antioxidant networks, triggers autophagy, and promotes mitochondrial biogenesis. A major benefit of fasting is that it causes a big uptick in AMPK activation. Other things do, too, like exercise, basic calorie restriction, and any situation where energy is being deprived or expended, but fasting is one of the more reliable paths.

Luckily, coffee doesn’t seem to inhibit AMPK. Caffeine improves endothelial repair via AMPK. Even chlorogenic acid, another coffee component, triggers AMPK.

Okay, so black coffee doesn’t seem to break the fast in any meaningful sense. What about all the things people like to add to coffee?

Common Additions to Coffee

Coffee With Butter/MCT Oil/Coconut Oil?

Technically, it breaks the fast. You’re ingesting calories (depending on how much fat you add, it could be a significant number of calories), and calories break the fast. But pure fat has little to no effect on insulin, blood glucose, or any of the other measurements that indicate a “broken fast.”

You won’t burn as much body fat. You’ll still burn plenty of body fat.

It will help you fast longer. Adding a little fat to your coffee can make fasting more tolerable. If you can only manage 12 hours on black coffee but a couple teaspoons of coconut oil help you go 24, the coconut oil might be a good addition.

It shouldn’t affect autophagy. Protein ingestion interrupts autophagy. Butter has a tiny amount of protein that shouldn’t interfere.

Coffee With Heavy Cream?

An ounce of cream has almost a gram each of carbohydrate (lactose) and protein. That. Some cream in your coffee won’t affect your fat burning very much, but it probably will inhibit some autophagy.

That said, remember that ketogenic diets increase autophagy too, and those definitely include food. This is all a matter of degree. It’s not a binary on-off switch. Less autophagy isn’t zero autophagy.

Coffee With Almond/Other Nut Milk?

As long as you’re avoiding the sweetened versions, or the ones that come fortified with extra protein, and you’re not adding a half cup at a time, a little nut milk won’t make a big difference. There is very little of anything in most nut milks.

Coffee With Cinnamon/Cocoa/Nutmeg?

Cinnamon is fine. It tends to reduce insulin resistance, especially the kind you get after a bad night’s sleep.

Cocoa powder is okay, but watch the amount. It’s a “whole legume” powder, so it has carbs, protein, and fat. Anything more than a teaspoon will overdo it. If you add cocoa, use defatted cocoa powder. Adding too much of the cocoa powder with fat included will reduce the effects of fasting.

Nutmeg is fine, too. Just avoid psychotropic doses.

Coffee With Stevia?

When you eat it with a snack containing 290 calories, stevia lowers glucose and insulin levels. I see no mechanism by which stevia could make the situation worse without a meal.

Coffee With Monkfruit Extract?

Monkfruit extract has an effect similar to stevia. It’s fine.

Coffee With Artificial Sweeteners?

There’s no good evidence they’ll impair the metabolic response to fasting, but there are other unwanted effects you should want to avoid.

Coffee With Collagen?

As much as I love (and sell) collagen, it is pure protein, and protein tends to activate mTOR and inhibit autophagy. This means that collagen in your coffee during a fast is probably fine for fat-burning (and may suppress appetite, helping you fast for longer) but will reduce the benefits of autophagy.

When You’re At a Coffee Shop

Order black coffee: drip, pour-overs, espressos, Americanos. That’s the most surefire way to maintain the fast.

Ask for heavy cream, don’t use the “cream.” The “cream” coffee shops tend to set out for customer use is actually half-and-half: half milk, half cream. That gives it a significant protein and carb load that will inhibit the effects of the fast. Instead, if you absolutely need something to add to your coffee, ask the staff for heavy cream.

Avoid nut milks. Coffee places often use sweetened nut milks, and they use entirely too much of it. An “almond milk latte” will have around 8 ounces of almond milk, far too much for your fast (even if it’s unsweetened).

That’s about it for coffee and fasting. If you have any further questions, don’t hesitate to ask down below. I’ll get to as many as I can in a future post.

Thanks for reading, take care, and enjoy your coffee!

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TAGS:  coffee, keto

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73 Comments on "Does Coffee Break an Intermittent Fast?"

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Rhonda
29 days 2 hours ago

No. It enhances the benefits of the fast.

NaturalGirl
NaturalGirl
28 days 17 hours ago

I totally agreed.

Anthony
Anthony
29 days 2 hours ago

Seems to me a great way to get the best of all worlds might look like: eggs and veggie for breakfast a couple times a week, perhaps a bulletproof coffee once or twice a week, and straight up black coffee a few times. Unless you are really “hard-core” and just fast everyday. I have a super active job so multiple times a week I can really feel I need a breakfast to be at my best.

Cicely
Cicely
29 days 10 minutes ago
Thanks Mark, this post was *really* helpful. I’ve been primal for 6 years and am usually in the 100-150g carb range. I’ve also been intermittent fasting (12-15 hours fasts daily, usually broken by 7-8AM) for over a year now. I just started keto last week. I’m on day 6 and have confirmed that I’m doing it right (using ketostix for now). Every day since day 2, I’ve tested in the high range for urine ketones in the afternoon, but I happened to do a 6-mile run yesterday afternoon (keeping my heart rate less than 130 (I’m 43) and feeling energetic… Read more »
Daniel
Daniel
28 days 23 hours ago

It will take some time to get fat adapted. Keep exercise light for a few weeks. When I went keto, the only times I really had carb cravings was after long bike rides in the summer in the first couple months.

Jen
Jen
28 days 23 hours ago

What about tea? Black tea, in particular..

Jen
Jen
28 days 23 hours ago

What about tea? Black tea, in particular.

KidPsych
KidPsych
28 days 22 hours ago

If you want to read about tea and fasting, this is a pretty amazing place to go –

https://idmprogram.com/blog/

Floyd Aldrich
Floyd Aldrich
28 days 23 hours ago

Recently I’ve learned how beneficial Kefir is,but it most likely stops a fast.

LlamaAnna
28 days 5 hours ago

Kefir is amazing, I can tell you that from personal experience. It had many unexpected positive effects for me. I expect it would interfere with fasting, but I would strongly suggest adding it to your eating window!

Floyd Aldrich
Floyd Aldrich
28 days 5 hours ago

Definitely,drinking both water and milk kefir.!

Adam
Adam
28 days 23 hours ago

Thanks Mark, I’ve been looking forward to more insight into coffee and fasting.

Caroline Fuerte
28 days 23 hours ago

Hi Mark, I realize this is a minor detail but could you help with the difference between half n half vs. cream in your morning coffee? When I look at the carb count for half n half, it seems insignificant enough. Is there really a big difference between cream and half n half to warrant one acceptable and one not? thanks so much!

Caroline Fuerte
28 days 23 hours ago

Hi Mark, I know this is a small detail, but I’m having a hard time understanding why half n half would be a no but cream a yes. Are they really so different? When I look on the carb count for half n half it is still only a gram. thanks!

Naomi W.
Naomi W.
28 days 19 hours ago

Caroline, check out my previous comment. If not having half-n-half in your coffee is a deal-breaker, then drink it.

Brian Stanton
28 days 22 hours ago

Hi Mark, I think you make a strong case for using coffee to enhance a fast. It makes me wonder what Dr. Satchin Panda, the brilliant Time Restricted Eating researcher, would say about all this – as he’s on the record recommending water only.
Another great article though, looking forward to meeting you at Paleo FX this year.

Stephany Pritchard
27 days 23 hours ago

I’m glad you mentioned Dr. Panda. I was wondering the same thing. From what I understand, anything beyond water triggers the enzymes that would prevent a autophagy. Is that incorrect?

KidPsych
KidPsych
28 days 22 hours ago

Take away: Coffee awesome!

kate
kate
28 days 22 hours ago

What about decaf coffee? Does it still have the benefits listed above?

Jordan Korte
Jordan Korte
28 days 4 hours ago

I would really like to know the answer to this, as well! I find that I feel muuuuch better when I abstain from caffeine, but love my coffee so still drink decaf.

virginia
virginia
27 days 22 hours ago

I understand that decaf still has caffeine, it just to a lower extent. Did you ever consider 1 coffee per day of regular coffee and decaf there after?

Karen
Karen
28 days 22 hours ago

Frappuccino? would that break a fast?

LlamaAnna
28 days 5 hours ago

Given the ridiculous amount of sugar in it I’m sure it would.

Mister_Root
Mister_Root
28 days 19 hours ago

Great post! I will sure stick to black espressos when I don’t intent to breakfast (most of the days actually).

“Nutmeg is fine, too. Just avoid psychotropic doses.” Thanks Mark laughed out loud here. I recall my buddies doing that when I was a teen but never resolved to try that psychedelic. Good thing too, “tumbling down the stairs without getting hurt or feeling anything” as my friend reported still goes against Primal Law #9 in my book!

Naomi W.
Naomi W.
28 days 19 hours ago

I’ve been fasting every Monday for the past 3 years. That’s 36-hrs from Sunday night till Tuesday morning. Not having coffee would be a deal-breaker for me. I have 3 cups of coffee on Monday, each with 1 T of half-n-half. If you think that’s not good enough, then stuff it. I always feel wonderful after my fast, and my body is trained to not need constant food-stuffing-in-my-face to regulate my blood sugar. When others are feeling weak and dizzy from lack of food, I can keep going and going like the Energizer Bunny.

Hugh Jorgan
28 days 17 hours ago

Personally I don’t think people should regularly schedule their fasts, should be more random, keep the body guessing… more “Primal” this way. Just my 2c.

Pam
Pam
28 days 19 hours ago

The link about nutmeg was very informational!

Becky
Becky
28 days 19 hours ago

Thoughts about Crio Bru and fasting?

KTT
KTT
28 days 17 hours ago

Hi Mark, what about taking some BCAA’s during the fast to spare muscles? I’m trying to gain muscle and do my fasted workouts with some BCAA’s in my water bottle. Does this limit the fast? Thanks!

Piper Kirby
27 days 21 hours ago

KTT. Amino acids are protein and protein breaks the fast. Sorry!

Prin
Prin
28 days 14 hours ago

In the tea post, would you please clarify effects of mixing even tiny amounts of protein with green tea? I read that it reduces the beneficial effects of fat burning.

Shary
Shary
28 days 4 hours ago
Plain green tea and black coffee are basically flavored water. When you start adding other components it becomes a horse of another color. Some people throw everything but the kitchen sink in their coffee. Doing so likely does break the fast, but there are degrees of fast-breaking. For instance, coffee (or tea) with a small amount of half & half in it–which does contain protein–isn’t nearly as much of a fast-breaker as, say, a chocolate chip cookie. Seems to me it’s all about how much work your digestive system has to do as to whether you can call it fasting… Read more »
Laura H
Laura H
27 days 16 hours ago
Actually, the digestive enzymes in your body (including, to some extent, insulin) are activated first by the flavor of food. So, even black coffee, tea and just flavored water could activate your digestive system enough to interfere with a fast. I’ve found it easier to prevent hunger while fasting by not introducing any flavor, I stick only to filtered water. Better safe than sorry, if I’m going to fast I want to make sure I’m not taking in anything at all that may hinder the results. All the articles fudging with whether this or that will break a fast are… Read more »
Eva
Eva
26 days 23 hours ago

I identify with this one; I find that coffee in general increases my appetite (I am currently trying to ween myself off of it, to at least take a break; took a 15 day break once, and felt great)…but I love the stuff! Yes; using Swiss Water decaf to help come off the coffee. Am currently researching how coffee may be increasing my cortisol. For me, a true fast would be without the caffeine. 🙁

Christian
Christian
28 days 13 hours ago

I put 2 tablespoons of soy lecitine in my black coffee – it contains plenty of choline which is superb for your brain – and it’s almost fat, so it should not break the fast, or does it?

TanyaEve
TanyaEve
28 days 13 hours ago

This is really helpful, thanks! I was wondering about this as a typical day for me is bulletproof coffee with some collagen, mid-morning coffee with a splash of cream and then not eating till lunchtime. If I really feel the need for breakfast, I’ll have it, though. I might play around with having collagen later in the day, if I’m not so busy on those days, or sometimes just going for black coffee instead.

Joanna
Joanna
28 days 10 hours ago

What about prescription medications and autophagy? I take daily thyroid meds in the morning on an empty stomach. Since I fast til lunch, I can push this forward until 9 or 10 am, keeping it within an overall 10 hour window (eating in just 6 hours). Sometimes I think it would be good to fast 36-72 hours to really amp up autophagy, but is that a waste of time if I still take the meds?

Jojo
Jojo
28 days 6 hours ago

Hi Mark, can you address another proposed benefit of fasting and the impact coffee could have on it? I’m speaking of… let’s call it ‘digestive rest’. In at least one interview, another researcher suggested that ingesting anything other than water during a fast would trigger the production of digestive enzymes with a lifespan of about 10-12 hours. So keeping all eating (including black coffee) inside that window would be the only way to avoid producing more of these enzymes and allow the digestive system to rest during the fast. Would appreciate your thoughts.

Kim
Kim
28 days 6 hours ago

Hi! Terrific article. What are your thoughts on Swerve?

Stephen
Stephen
28 days 5 hours ago

Can someone explain how non-dairy powdered creamers play into this?

I assume because it’s processed it must be bad, but what impact does it have in our diets and especially with fasting?

Mark
Mark
22 days 20 hours ago

First ingredient in those is “corn syrup solids.” No thanks.

Elizabeth Resnick
28 days 5 hours ago
This was super helpful…thank you! I do put collagen and fat (coconut oil or grass fed butter) in my coffee, along with other “add -ins” depending on my mood. Many times raw cacao, maca and cinnamon. I just find doing the collagen in the am insures that I actually take it, and it is the one thing that I can’t live without (mostly for my skin…firmer now at 51 than ten years ago) Some days the blended coffee holds me till lunch or beyond, other days (like today) I’m truly hungry in the am. So for now I’m just going… Read more »
Art
Art
28 days 3 hours ago

Mark, I’ve hard Dr. Rhonda Patrick and Dr. Satchin Panda say that consuming anything the body has to metabolize starts some biological clock having to do with your circadian rhythm. So I’ve been operating under the assumption anything but water breaks fast. What say you?

Daniel
Daniel
27 days 17 hours ago

I also listened to that podcast. My take is that I’m not taking a break from my circadian rhythm, so drink that coffee and let it get started.

Bobby
28 days 19 minutes ago

It’s good to know that it does not break my intermittent fast. I try to fast one day a week for 18 hrs or so and usually drink three cups of black coffee during that time. I fast from 8:00 one evening till late afternoon the next day. Typically I end it with small protein snack around but try to keep it under 100 calories. I am interested in the upcoming blog post about fasting and tea.

Joanne
Joanne
27 days 21 hours ago

Why is there no mention of coconut milk or coconut cream ?

David
David
27 days 18 hours ago

Thanks for this website. It clarifies so much hard to understand nutritional complications. Keep it up and health to all.

Marchie Hya Condon
27 days 16 hours ago

Hi Mark,

I always wondered..

therefore normal, organic, full cream milk in coffee would be FOOD that instantly breaks the fast..

Thank you for clarifying

Warmly,
Marchie

Laura H
Laura H
27 days 16 hours ago

That’s OK, I’ll continue to truly fast by sticking to drinking only filtered water and not taking any supplements or adding anything to my water. That way I’m not taking any chances that the fast is being broken or minimized by adding chemicals or nutrients that change the benefits I’m fasting for. I’ve done 12 day water-only fasts with no problem at all, so there is no need to add anything and hope it’s not breaking the fast.

Larissa Nowak
27 days 16 hours ago

What are your thoughts on goat milk?

Adam
27 days 13 hours ago

Thanks mark this is so timely I am currently doing IF and trying my first 24 hour fast today so will have a few cups of black coffee to get me through. Is black tea the same? Doing a gut reset and on the Pau D’Arco tea at the moment.

Prakhar
27 days 12 hours ago

At some places, I’ve read coffee on an empty stomach every day is not good. How true is that? Thank you!

Prakhar
27 days 12 hours ago

For stomach, I mean.

Mark
Mark
22 days 20 hours ago

I’ve done extended fasts with only coffee and water. No issues.

George Sadler
George Sadler
27 days 7 hours ago

So glad you posted this. I usually fast 14-16 hours every day. I generally break the fast with a cup of coffee, not because I am hungry but because I enjoy a good cup of coffee. I buy organic green coffee beans, I roast them then cold brew them. Mornings are usually 2 cups of black then in the afternoon a couple of cups with almond milk and maybe a few drops of stevia. Thanks for the article

Allison
Allison
27 days 4 hours ago

Thank you for publishing this article and slowing down the hamster wheel in my brain for at least the morning!

Vince
26 days 22 hours ago

I’ve seen both sides to this discussion before. I agree with your idea that it depends on what you’re looking for. People fast for many different reasons and define fasting in many different ways. There is no single answer to the question and that’s entirely okay.

Arnaud Marthouret
26 days 20 hours ago

I was hoping for honey, but alas didn’t see it.

Teresa Phillips
26 days 16 hours ago

So coffee increases cortisol. Is increasing cortisol a beneficial or detrimental thing to do during a fast? I speculate that it would add to stresses in the body but I suppose it matters how well a person manages cortisol.

Animanarchy
Animanarchy
25 days 23 hours ago
Well this comment doesn’t have all that much to do with coffee. More about nutmeg. Don’t get me started, eh? I will say I don’t recommend huge doses. Just reminded me that I found a previously opened but almost full bottle of Pure Leaf tea today. After holding it up to the light to examine and making sure there was nothing floating in it and then smelling it, I decided to keep it. Yeah, I’ll finish a stranger’s drink or food (got cold take-out ribs from a dumpster for breakfast yesterday!) – hope it does’t have rohypnol or something like… Read more »
Dave
Dave
25 days 8 hours ago

I recently read that the ingestion of the caffeine is what breaks the fast as the liver is activated to metabolize the stimulant.

The again, I read the first paragraph and realized that I do get hung up on minutiae !

Paleo-P
Paleo-P
24 days 3 hours ago

So, if one were to eat dinner at 6pm, and not eat again until the next day around noon (18 hours between meals)… that’s technically intermittent fasting? That *could* explain why I don’t weigh 600 lbs. Don’t get me wrong – I weigh too much, but not morbidly so. (Not yet at least, lol.)

Lisa Hughes
15 days 14 hours ago

Thanks for this. I was just wondering about it a few weeks ago.

Vania Rossi
13 days 4 hours ago

Will adding one or two teaspoons of sugar to coffee break the fast?

Aubree
Aubree
13 days 2 hours ago

Hi everyone! I’m currently having to take antibiotics to clear up an eye infection and I really want to do at least a 24-36 hour fast to stimulate autophagy and just to feel better. Love this post about coffee not interfering (what a relief!) I’m wondering if the antibiotics (the kind I’m on don’t necessarily have to be taken with food) or my other regular vitamins will inhibit autophagy? Thanks in advance!

Dailycupo
12 days 14 hours ago

I heard about breaking fast with coffee but I thought before reading this article that it’s not good for health but now I see it is totally wrong! I am gonna also try in this coming Ramadan’s fast-breaking with a sip of coffee. Thanks to this website 🙂

Michel
10 days 23 hours ago

What about using MCT powder in coffee? I am doing a program of intermittent fasting to increase autophagy, I don’t want to loose that benefit, but it’s hard for me to drink black coffee

Nic
Nic
2 days 10 hours ago
Hello I’d like some helpful honest advice regarding a coffee substitute made from malt and chicory. I have started fasting away from work and during a period of little exercise due to injury but when I go back to work; 12 hrs a day, 7 day week for 4 weeks I will be exercising again. I gave up caffeine in January and cut swiss water decaf in march. This has hugely improved concentration, irritability and irrational emotions, and my sleep. Getting rid of the coffee lost the bloats and constant gurgling. So I found a coffee substitute because nothing else… Read more »
Matt
Matt
1 day 5 hours ago

Not related to coffee, but what are you thoughts on BCAAs during a fast? Specifically, for those that participate in intense training (cross fit, HIIT, bodybuilding, etc) during the fasted period, do you think adding BCAAs is beneficial or does it break the fast? Does it have a similar impact to the fast as you describe collagen in this post?

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