Dear Mark: What Breaks a Fast Follow-Up

For today’s edition of Dear Mark, I’m answering a round of questions drawn from the comment section of the “What Breaks a Fast” post. You folks had tons of follow-up questions about whether other types of foods or compounds break a fast. Does a teaspoon of honey? Does elevated insulin from BCAAs? Does coconut milk? Does pure prebiotic fiber? What about longer fasts—are they recommended? And how about unsweetened cocoa powder? What explains my ability to predict your questions? Do sausages break a fast? Does liquor? How should you exercise? (For questions on supplements, check out this week’s feature: “What Breaks a Fast: Supplements Edition.”)

Let’s dig right in:

Hey, what about honey? 1 tsp in morning tea?

A teaspoon or less of honey is fine and won’t negate the benefits of fasting. I alternate between doing collagen coffee and coffee with cream and teaspoon of sugar (which was my typical morning coffee for over a decade). No reasonable person should fear a teaspoon of sugar or honey.

For what it’s worth, honey isn’t “just” sugar. It elicits a more beneficial (or less negative) metabolic response than other forms of sugar.

I’m shocked about the BCAA. I used to fast and take BCAA’s (yes, to continue dynamic exercise). I used to find it extremely difficult to fast compared to now when I fast without taking them. Does that mean that the insulin response made fastic more difficult?

It’s possible. Insulin impairs lipolysis—the release of stored body fat into circulation for energy usage—and the success of fasting depends on lipolysis. Without lipolysis, you can’t access all that stored energy.

Thank you very much for this info!! I am a butter-coffee-for-breakfast drinker, and I always worry about the ingredients breaking a fast. Could you please comment on coconut milk (in the can)? I love putting that in my coffee/breakfast.

Coconut milk is a less concentrated source of medium chain triglycerides, or MCTs (as in MCT oil). MCTs convert directly to ketones, making MCT oil and to a lesser extent coconut oil or coconut milk a potential “boost” for fasting. Still, energy is energy, and any energy you take in is energy you won’t be pulling from your body.

I find MCTs and coconut to be more useful when someone is just getting the hang of fasting or ketosis—as a nice boost to get things moving in the right direction.

Keep your coconut milk under a tablespoon and you’ll be fine.

Does prebiotic (resistant starch) fiber break a fast? Acacia senegal or potato starch? Thanks!

No. If you’re worried, test your postprandial blood sugar after eating the fiber.

Great input Mark as someone 3days into a 7day water fast with electrolytes of course what’s your view on longer fasts.

Check out the post I wrote on long fasts. Potentially beneficial but the risks accumulate the longer you go. You just have to be even more careful and methodical.

How about unsweetened cocoa?

A tablespoon runs just over 12 calories (depending on the brand; some cocoa powders contain more fat and thus more calories), with around a gram of net carbs and a gram of fat. Also a nice source of potassium and magnesium, along with a ton of polyphenols which can have fasting-mimicking effects on their own.

Eating enough unsweetened cocoa powder to knock you out of your fast would be incredibly repulsive. Probably impossible.

Cocoa is definitely a nice addition.

Okay it’s almost creepy the way Sisson answers my questions before I even ask them! I was wondering about this yesterday and then this post popped up in my inbox.

How does he do that…? ?

Kraft-Heinz has a strong relationship with Google and Amazon, and the Kraft acquisition gave me access to Alexa/Google Home datasets and the ability to predict what my readers are wondering about.

Just kidding, though it’s scarily not out of the realm of possibility anymore.

What about a small snack of paleo sausages, smoked or dried? So meat and fat (beef, pork or lamb), and some spices. Maybe 100g worth.

Well, that’s a legit snack bordering on a small meal. That will break the fast, but it’s not all for naught. There is the whole “fasting-mimicking diet,” where you eating very few calories for several days out of the week and retain many if not most of the benefits of full-on fasting.

Let’s just say if you ate a small snack of paleo sausages on your “fasting” days, you’d still be way ahead of 99% of people.

But do try a full-on fast at least once. You might surprise yourself.

Great post! What about alcohol? Specifically, a shot or 2 of liquor. I would assume beer and wine would break a fast, but what about whiskey or tequila?

When alcohol enters the system, utilization of all other energy sources is suspended until the alcohol is burned. Back in 1999, researchers did a study where they gave fasting adult men the equivalent of a couple shots of liquor. They stopped releasing stored body fat, stopped burning body fat, and began burning way more acetate (a product of ethanol metabolism). They didn’t exactly “break” the fast, but all the metabolic trajectories we love about fasting took a big pause.

Good morning Mark,
How does one exercise in the morning while fasting? When to eat?

You can exercise any way you like, but I change how I train based on when I’m going to break the fast with food.

If I’m going to break the fast with a meal right after, I train any way I like. I’ll do sprints, HIIT, weights, anything.

If I’m going to keep fasting after the workout, I like to stick to strength training and low-intensity movement (walking, hiking, standup paddling). The strength training is essential during a fast because it’s an anabolic signal to your muscles—move it or lose it. Simply lifting heavy things during a fast can stave off muscle loss.

That’s it for today, folks. Thanks for stopping by.

TAGS:  dear mark

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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18 thoughts on “Dear Mark: What Breaks a Fast Follow-Up”

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  1. These questions get so fun and I am still hoping to hear if taking medications break a fast? Any thoughts? Ideally anti-anxiety medications.

  2. “No reasonable person should fear a teaspoon of sugar or honey.”

    Thanks Mark! There’s so much paranoia in the world. Good call.

    1. And it “helps the medicine go down, in a most delightful waaay!” 😉

  3. Fasting is all about the context in which you are doing it and what your goals are. Some of these questions are just plain silly (you really eat just cocoa powder to break a fast). Anything that stimulates digestion is breaking a fast whether it has calories or not.

    1. And, one must remember that digestion starts in the mouth with the activation of the taste buds and saliva glands. Therefore, something that just has “taste” with no calories is going to break your fast. That means, you can have plain water. Period. Otherwise, you are breaking the fast to some degree.

  4. “Simply lifting heavy things can stave off muscle loss.” Thank you! This is a great reminder! Just fasting can cause you to lose muscle. I will incorporate lifting during fasts.

  5. WRT BCAA, I’d expect that the insulin response would be at the same time as a glucagon response and therefore would not impair lipid metabolism.

  6. Simply lifting heavy things can stave off muscle loss. Thank you! This is a great reminder! Just fasting can cause you to lose muscle. Well written…with some great inputs.
    this is chock full of useful information I read a lot of blog posts but this is very informative
    I can’t wait to dig deep and starts utilizing the resources you have given me. your exuberance is refreshing. I will incorporate lifting during fasts.

  7. Just a friendly reminder that drinking on an empty stomach is probably not a good idea… ?

  8. I kept reading through your other posts about women and IF. I’ve been doing it trying to do the 16/8 for last couple weeks. I didn’t know there were prerequisites to starting it I think I manage all except I’m not a keto dieter. I do eat more fat and protein than carbs simply because I can’t eat grains except rice occasionally. I read that this type
    Of IF can cause chronic stress which my body does Not need lol! However I do enjoy it because I’ve never been an early eater and I feel sharper and even when I’ve had times I couldn’t exercise I maintained my weight and didn’t gain which is of course extremely easy for this 48 year old perimenopauser!

  9. What about a half scoop of metagenics thermaphaseprotein detox powder in water? Will this break my fast?

  10. You featured and answered the first question I asked! Thank you.
    And those guacamole bites look amazing! I’ll have to try those.

  11. Mark,
    One item I did not see addressed was a green supplement, such as Athletic Greens or Amazing Grass. I typically drink a scoop with a large glass of water in the morning. Does it break my fast?

  12. CBD Oil should be considered as anti-anxiety medication as it is used broadly to treat various health disorders

  13. Thanks for all of your informative and rational dietary advice Mark. My wife and I love your creamy citrus dressing 🙂

  14. In the case of alcohol, what if I’m ingesting it very, very slowly, in very small sips? Say, a glass of wine over the course of 1h. I guess it’d apply to other things as well (although I can’t see myself sipping a single coffee with some cream for that long)?

  15. “Keep your coconut milk under a tablespoon and you’ll be fine.” Your previous post had this same advice for every source of pure fat.

    Is this simply to limit the amount of additional calories you will have to burn? Or is the amount of fat inversely proportional to the magnitude of the fasts benefits?

    I frankly don’t care about the 200 additional calories of 2 tablespoons of grass fed butter in my coffee, unless of course it proportionally decreases the effectiveness of autophagy for example.

    Thanks Mark!