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Does Bulletproof Coffee Break a Fast?

Bulletproof coffee, sometimes called butter coffee or keto coffee, is a high-fat, high-energy drink intended to start your day off right. It combines coffee, MCT oil or just coconut oil, and grass-fed butter to make your morning coffee that much more energizing.

It was created for the bulletproof diet but has become popular among keto dieters and those who follow other low-carb, high-fat diets.

In this article, we’re going to take a deep dive into bulletproof coffee.

Does Bulletproof Coffee Break a Fast?

Technically, bulletproof coffee does break your fast. Intermittent fasting is defined as a period of not consuming any calories, so a bulletproof coffee will break this. However, the aim of fasting is to move your body into the metabolic state of ketosis to promote weight and fat loss.

A bulletproof coffee, being high-fat and low-carb, will not move you out of ketosis. That is why it is often used on the ketogenic diet.

While it does technically break your fast, you can consume bulletproof coffee during fasting periods on any intermittent fasting method and still remain in ketosis.

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What Is Bulletproof Coffee, and How Do You Make It?

Bulletproof coffee, or butter coffee, is black coffee made from high-quality coffee beans. It is supplemented with fats, including high-quality grass-fed butter and MCT oil, usually derived from coconut oil.

It is very important that you use high-quality fats in your bulletproof coffee to ensure you’re getting the right kind of fats in your drink.

Bulletproof coffee is considered a good way to start your day. Unlike many processed and refined breakfast options, this coffee does not increase blood sugar levels and leave you with hunger cravings.

Instead, this coffee can help you feel satiated and more alert and helps your body remain in the fat-burning state of ketosis for a little longer, promoting weight loss.

Generally, drinking 2–3 cups of butter coffee each week is recommended. In addition,  you should drink it earlier in the day to wake you up for the best effect.

Bulletproof coffee recipe

A standard bulletproof coffee recipe looks something like this:

  • 1 cup of black coffee
  • 1–2 tablespoons of MCT oil
  • 1–2 tablespoons of grass-fed butter or ghee

How Bulletproof Coffee Affects Fasting

Bulletproof coffee is a high-fat, high-energy drink that you can consume during fasting periods. Though it will technically break your fast, the coffee can still help you to remain in ketosis because it does not raise your blood insulin levels.

It is generally recommended that you drink coffee in the morning to get the energy boost you need from it to start your day. Whatever time your fasting or eating window starts, refrain from drinking anything caffeinated after 3 pm so as not to affect your sleep.

Intermittent fasting may seem like a daunting way of losing weight which is why you should always work up to long fasting periods. You could also use an app like the DoFasting app to make it easier.

The app provides a space for you to track your food, calorie, and water intake and space to follow your progress. It also offers fasting-friendly recipes suited to a range of dietary restrictions for you to try out.

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5 Benefits of Bulletproof Coffee

Bulletproof coffee comes with many health benefits, which is why it is so popular with fasters and those on the keto diet. Below we have listed some of the benefits you may experience if you choose to drink bulletproof coffee.

1. Promotes fat burning

As butter coffee helps you to remain in ketosis, it helps to promote fat burning. Ketosis is the state in which the body burns stored fat for fuel rather than blood sugar which can help to promote weight loss and fat reduction.

2. Controls hunger and promotes the feeling of satiety

Bulletproof coffee is known for its ability to help you feel less hungry and promote feelings of satiety. This helps you to stay on track with your fast and can help to promote a reduced caloric intake, which also supports weight loss.

3. Stabilizes blood sugar

As this coffee is low in carbs and high in fat, it will not raise insulin levels in the blood. This can be useful to those with type 2 diabetes as it can help them manage blood sugar levels and may promote insulin sensitivity.

In addition, stabilizing blood sugar levels helps you to remain in ketosis for longer, making sure the body burns fat for as long as possible.

4. Boosts your exercise results

There are a few reasons that bulletproof coffee is great for exercise and is a good choice for a pre-workout drink. To begin with, MCT oil can promote ketone production and boost your blood ketone levels. Ketone bodies give your muscles the fuel to work out harder and for longer.

Caffeine is also a great stimulant for a workout. You will find that if you drink coffee before a workout, you will last longer. It also speeds up your metabolism, which helps you to burn fat faster while exercising.

5. Improves brain function

Bulletproof coffee is thought to boost brain function, improve focus, and promote mental clarity. MCT oil helps raise blood ketone levels, and ketone bodies are an excellent fuel source for the brain.

In addition, caffeine helps to improve alertness and focus, and it helps you to feel more energized.

Are There Risks to Drinking Coffee While Fasting?

As with many aspects of fasting, drinking coffee may come with some risks while fasting. These risks include:

  • It could increase your blood pressure: Those with high blood pressure should consult a medical professional before consuming black coffee on their fasts, as coffee on an empty stomach can raise blood pressure.
  • May cause sleep problems: Drinking coffee too late in the day can cause difficulty sleeping and insomnia, so you need to avoid it after about 3 pm.
  • Could cause gut and digestive problems: Drinking coffee on an empty stomach can activate the digestive system and should be avoided by anyone fasting to reset their digestive system.
  • May irritate the stomach lining: As an acidic drink, coffee may irritate your stomach when drunk on an empty stomach.

What Else Breaks a Fast?

A fast means a period of zero calorie intake, which means that eating or drinking anything with calories in it is classed as breaking a fast. However, there are methods of fasting where you can eat a small number of calories. This is referred to as ‘dirty fasting’ and allows you up to 100 calories during fasting hours.

Fasting is also used to induce a state of ketosis. Ketosis will not be broken if you continue to keep your carbohydrate intake low. Eating high-fat, low-carbohydrate foods during a fast will not disrupt ketosis.

Foods that would break ketosis include grains, starchy vegetables, sugars (like honey, maple syrup, and regular table sugar), and baked goods.

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Bulletproof coffee is a high-fat coffee drink that combines black coffee with healthy fats like those found in butter, ghee, plain coconut oil, and MCT oil. It is thought to be a good way to break your fast without increasing blood sugar and insulin levels.

Bulletproof coffee is a favorite of those following a keto diet and fasters as it does not move you out of ketosis and can help promote weight and fat loss. It may also boost your athletic performance and brain function.


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This is an evidence-based article that includes scientific citations. DoFasting’s professional writers and editors prepared the content, which a team of medical experts verified to be accurate.

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