Bulletproof Coffee And Intermittent Fasting Explained

It seems like everyone’s doing some sort of intermittent fast. Fasting's benefits entice me, but I get hangry easily, so I’ve skipped this wellness trend. Though I recently heard you can drink bulletproof coffee while intermittent fasting. Sip rich, satisfying coffee while fasting? Yes! Wait… is there a catch? It’s my mission to find out.

Drinking bulletproof coffee while intermittent fasting will break your fast; however, it won’t negate all benefits of this eating pattern. While you won’t experience the full range of fasting results, your body should maintain ketosis, and you might even experience some enhanced fasting effects.

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So, drinking bulletproof coffee (you may know it as keto or butter coffee) does influence your fasting results, but it might not sabotage the specific results you’re after. I’m intrigued. Which results are still possible or potentially even boosted when you drink bulletproof coffee while intermittent fasting?

Intermittent Fasting (Briefly) Explained

Intermittent fasting has been found to help us live longer, healthier, fitter, leaner lives. This way of eating can encourage weight loss, fat-burning, and longevity while boosting our brains and helping us fight diseases and repair our cells.

From Eat Stop Eat and OMAD to 16/8 and 5:2, there are so many ways to go with the intermittent fasting trend. All plans have something in common: switching between set periods of fasting (for up to 48 hours at a time) and eating for wide-ranging wellness benefits.

When we don’t eat regularly throughout our waking hours, we deplete our sugar stores and burn fat for energy instead. And when our main fuel is fat, marvelous changes happen in our bodies and brains that bring about intermittent fasting’s impressive results.

As impressive as the results are, if there’s a hack to improve them, I want in. Many bulletproof coffee fanatics swear that coupling this cultish creamy coffee with intermittent fasting can maximize many of fasting’s effects. Could there be a way to make fasting not only more doable but also more effective?

Does Bulletproof Coffee Affect Intermittent Fasting Results?

It turns out there is a catch. A big one. If you’re drinking standard high-calorie bulletproof coffee, you’re technically not fasting. So you won’t get the same benefits.

You see, to trigger the changes in your body that will let you experience fasting’s full benefits (including the longevity boost, cell-healing, and disease-fighting), you should take in close to zero calories and nutrients during your fasting period.

Bulletproof coffee is made from high-quality coffee, unsalted grass-fed butter, and fast-digested medium-chain triglyceride (MCT) oil. The ingredient quantities vary, but it's usually a cup of coffee, 1–2 tablespoons of butter, and 1–2 tablespoons of MCT oil.

This rich brew gives you a good dose of calories and fat (about 235 calories and 26g of fat per cup made with coffee and 1 tablespoon of each of the fats), so, strictly speaking, drinking bulletproof coffee will break your fast and cut down the number of benefits you’ll experience.

Calories And Fat In Bulletproof Coffee

Here’s a closer look at the fat and calories in bulletproof coffee’s ingredients:

Ingredient Calories Fat
1 cup (8 oz) coffee 2 0
1 tablespoon MCT oil 130 14g (14g saturated fat)
1 tablespoon butter 102 12g (7g saturated fat)


The Downsides Of Drinking Bulletproof Coffee While Fasting

If you drink bulletproof coffee while intermittent fasting, you’ll experience diluted disease-fighting, anti-aging power. This is because the calories and fat you swallow in your coffee reduce the effectiveness of a process called autophagy, which is responsible for fasting’s protective, regenerating effects.

Autophagy is your body’s way of clearing out damaged cells and replacing them with healthier ones to help your body and brain age better. If you’re fasting to get these specific effects, stick to drinking only water during your fasting period.

If you're fasting for weight loss, bulletproof coffee's high-calorie content might work against your goal. Remember to factor in these calories when you plan the meals for your eating periods so you don’t go over your target number of calories for the day.

Something else to keep in mind if you’re watching your calories: bulletproof coffee gives your body energy and fat, but hardly any other nutrients. So, choose the rest of your calories wisely. Eat nutrient-dense foods during your eating periods to give your bod all the vitamins, minerals, and other nutrients it needs to thrive.

Another potential pitfall of making bulletproof coffee your daily brew, whether you’re intermittent fasting or not, is that it’s high in saturated fat. While it’s inconclusive whether saturated fat increases your disease risk, many health experts warn against eating mega-doses of this type of fat.

We all respond differently to high-fat diets. Some of us will experience raised cholesterol levels and heart disease markers, while others will stay within healthy ranges. So, to be safe, keep track of your cholesterol levels if you start drinking bulletproof coffee on the reg.

The Benefits Of Drinking Bulletproof Coffee While Fasting

Although bulletproof coffee’s high calorie and fat content will influence your fasting results, this isn’t necessarily a bad thing. Depending on your reasons for fasting, drinking this fat-fortified coffee might even make it easier for you to reach your goals.

Drinking Bulletproof Coffee Can Make Fasting Easier

An obvious perk of drinking bulletproof coffee while fasting (the one I find especially attractive) is that it makes you feel full and, therefore, more likely to stick it out till the end of your fasting hours. It’s the fat, particularly the MCT oil, that fights off hunger so you can keep going strong without urges to nibble.

Drinking Bulletproof Coffee While Fasting Can Energize You

Bulletproof coffee can also help you feel alert and focused and give you lasting energy. There are two mechanisms behind the sustained energy boost:

1) MCTs are broken down quickly and can then either be used as an instant energy source or turned into ketone molecules and saved for later longer-lasting energy.

2) Fat can slow the absorption of caffeine, potentially extending caffeine’s energizing effects.

Drinking Bulletproof Coffee While Fasting May Boost Fat-Burning

If it’s a more sculpted body you’re after, and you can’t see yourself getting through your fast without a cup of buttery java, breathe easy knowing bulletproof coffee doesn’t appear to interrupt fasting’s fat-burning ketosis process.

It’s believed bulletproof coffee might even fire up fat-burning and help reduce fat storage. Again, we have MCTs to thank for these effects.

Drinking Bulletproof Coffee While Fasting May Help Your Gut

More perks of MCTs: when combined with coffee's caffeine, these fats can speed up your metabolism a little and might also help keep everything moving smoothly through your digestive system. MCTs may also improve your gut environment by encouraging good bacterial growth. And a healthy gut promotes overall wellbeing.

Drinking bulletproof coffee while fasting boosts your brain clarity, energy levels, and metabolism while also improving your gut environment, helping you stay regular, curbing your cravings, and keeping you feeling satisfied – and it does all this without knocking you out of fat-burning ketosis.

Lite Bulletproof Coffee Recipe

Here's a way to sneak in a creamy-ish coffee drink without changing your fasting results too much: mix just 1 teaspoon of coconut oil or MCT oil with your coffee. Experts say the fat and calories in this skimpy version of bulletproof coffee are unlikely to trigger a significant metabolic reaction.

You can either stir the oil into your coffee or whizz the ingredients in a high-speed, heat-resistant blender until frothy (about 30 seconds). The result: an MCT-enhanced, creamy, vegan-friendly coffee.

Can You Make Bulletproof Coffee With Decaf?

If you’re sensitive to caffeine or just prefer to avoid it, you can make your bulletproof coffee decaf.

You won’t get the benefits of the MCTs-caffeine combo, but at least you’ll sidestep the jitters.

Can You Add Sweetener To Bulletproof Coffee While Fasting?

You probably know that sweetening your bulletproof coffee with sugar or honey is a no-no, as you want to skip carbs to keep your blood sugar and insulin levels stable, but is it okay to use calorie-free artificial sweeteners?

Although these sweeteners don’t contain enough energy or nutrients to break your fast, they can still trigger changes in your body that clash with fasting goals.

Curiously, artificial sweeteners can make you hungry – something you definitely want to avoid while you’re fasting. The sweet taste tells your body to release insulin. The insulin can then drop your blood sugar, which can ultimately rev up your appetite.

Artificial sweeteners have also been found to unbalance the gut environment, increasing your weight gain risk.

How Much Bulletproof Coffee Should You Drink While Fasting?

Whether you make your bulletproof coffee skinny, decadent, or decaf, stick to max one cup a day. And if you're fasting for weight loss, remember to add your coffee's calories to your daily total.

Depending on how you make your bulletproof coffee, you’ll get up to 470 calories and 52g of fat per cup (this is for a cup of coffee with 2 tablespoons of MCT oil and 2 tablespoons of butter added).

If you add just 1 tablespoon each of MCT oil and butter to your coffee, you’ll cut the calories and fat in half: about 235 calories and 26g of fat per cup.

For the lite version, with only a teaspoon of MCT oil or coconut oil added to your cup of coffee, you’ll get about 40 calories and 5g of fat.

Does Black Coffee Affect Fasting Results?

Since it’s bulletproof coffee’s calories and fat that break your fast, does calorie- and fat-free black coffee break your fast? Most experts say no. It’s believed that 1–2 cups of black coffee generally won’t give you enough calories or nutrients to create a big enough metabolic change to break your fast.

So, drinking a cup of black coffee during your intermittent fast shouldn’t break your fast or sabotage your results.

The Benefits Of Drinking Black Coffee While Fasting

Moderate amounts of black coffee can affect intermittent fasting results in a good way, however.

Coffee might strengthen fasting benefits like enhanced brain function and dropped risk of inflammation and heart disease. And the caffeine hit might even stop your appetite from raging out of control.

Research says that drinking moderate amounts of coffee while intermittent fasting might also decrease your risk of diabetes, age-related brain diseases (like Alzheimer’s), and metabolic syndrome (characterized by symptoms including raised blood pressure, cholesterol, and blood sugar levels).

The Downsides Of Drinking Black Coffee While Fasting

If you start downing bottomless cups of coffee to keep yourself going during your intermittent fast, you'll take in too much caffeine, which will likely make you jittery, get your heart racing, and up your blood pressure.

Drinking too much coffee will always cause problems, but it's especially troublesome when you do it on an empty stomach while fasting. By overdoing the caffeine, you risk developing not only the shakes but also spiking your cortisol (stress hormone) levels.

High cortisol levels can stimulate a hormonal response that increases blood sugar. When you're buzzing from excessive caffeine, you might also struggle to get decent shuteye, which can harm your metabolic health over time.

If you’re fasting for better blood sugar control and metabolic health, drinking too much caffeine will clash with this goal. Rather limit yourself to a cup a day.


If you’re fasting to fire up your fat-burning and get your blood sugar levels under control, you might be able to get the results you want without giving up your daily creamy coffee hit. Just keep it to one cup a day (whether bulletproof or black) and eat plenty of nutrient-dense foods during your eating periods.

Perhaps you're like me, likely to ditch your fast at the first hunger pang. If this is the case, drinking bulletproof coffee might stop you from nibbling during your fasting hours. You might not experience total fasting benefits, but you’ll still get more benefits than if you’d broken your fast to eat a pancake stack with extra syrup.



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