Keto Coffee for Beginners: Butter vs. MCT Oil Explained

Keto coffee is brewed coffee blended with fat, usually butter, MCT oil or both. Butter mainly adds creaminess, flavor and saturated fat. MCT oil adds medium-chain fats that the body turns into ketones more readily than ordinary fats, but too much at once commonly causes stomach discomfort or diarrhea. For a first cup, Bulletproof’s own recipe starts newcomers on 1 teaspoon of MCT oil and builds up over several days, and blends the coffee for 20-30 seconds until it looks like a creamy latte.

This guide explains what each fat adds, what the published studies on MCT oil found, and how to make a first cup. It draws on the Bulletproof recipe, USDA nutrient data, the US Dietary Guidelines and peer-reviewed studies on MCT oil. It is general information, not medical advice. If you have a medical condition, take regular medication or are pregnant, ask your clinician before adding a high-fat drink to your routine.

What Is Keto Coffee and Why Do People Drink It?

Keto coffee, often called butter coffee or Bulletproof coffee, comes from Bulletproof. The company says entrepreneur Dave Asprey created the recipe after an experience with yak butter tea in Tibet. Its current recipe is 1 cup (8-12 ounces) of brewed coffee, 1 tablespoon of C8 MCT oil and 1 tablespoon of grass-fed ghee, blended for 20-30 seconds until it looks like a creamy latte; the same page says you can adjust the amount of butter or ghee.

People on low-carbohydrate or ketogenic diets drink it as a breakfast replacement that adds fat without adding carbohydrate. Bulletproof markets it for sustained energy, fullness and focus. Those are the company’s claims. The studies below measured blood ketones and side effects; they did not test butter coffee as a breakfast.

The Science Behind Fat in Your Coffee

The research on this drink is mostly research on MCT oil. MCTs are triglycerides with fatty acids 6 to 12 carbons long. A 2017 study by Courchesne-Loyer and colleagues explains that they are absorbed quickly from the gut into the liver and broken down faster than long-chain fats, which is why they raise blood ketones.

What the studies found:

• MCT oil raises ketones modestly. In that study, 10 healthy adults took 10, 20 or 30 g of MCT oil with breakfast. Compared with breakfast alone, MCT oil taken without emulsification doubled ketone production, with no significant difference between the three doses.
• C8 is the most ketogenic type tested. A crossover study of 9 adults by Vandenberghe and colleagues found that pure C8 (caprylic) oil produced the highest ketone response of the oils tested. Coconut oil, in the same study, peaked at 25% of the C8 ketone peak.
• Emulsifying helped. In Courchesne-Loyer’s study, MCT oil emulsified into lactose-free skim milk raised ketones 2- to 4-fold, more than the same dose taken unemulsified. The total number of side effects did not differ significantly between the two forms, but there was less diarrhea with the emulsion at the 30 g dose.
• Caffeine may add a little. A 2021 review in Frontiers in Nutrition says consuming MCTs with caffeine may slightly increase their ketogenic effect.

None of these studies measured weight loss, focus or hunger from keto coffee, so they do not show that the drink does any of those things.

Butter in Keto Coffee: What You Need to Know

Bulletproof’s 2013 recipe card calls for 1 tablespoon of grass-fed, unsalted butter or ghee, building up to 2 tablespoons or more over several days.

What Does Butter Add to Your Coffee?

Bulletproof’s card says grass-fed butter adds “a rich creaminess” to the coffee. It also adds energy and saturated fat. USDA FoodData Central lists unsalted butter at 717 kcal and 50.5 g of saturated fat per 100 g, and 1 tablespoon at 14.2 g. By those figures, 1 tablespoon of butter adds about 102 kcal and about 7.2 g of saturated fat.

That saturated fat is the main thing to weigh. The US Dietary Guidelines advise adults to get less than 10% of daily calories from saturated fat, which their fact sheet translates into a simple rule of less than 20 grams a day on a 2,000-calorie diet. Two tablespoons of butter, the amount Bulletproof’s card suggests building up to, would come to about 14 g by the USDA figures, before any other food that day.

Butter, in short:

• Adds the creaminess Bulletproof describes.
• Contains dairy.
• Adds a substantial share of the saturated fat the Dietary Guidelines suggest for a whole day.
• Has no ketone data in the studies above, which tested MCT oil and coconut oil, not butter.

MCT Oil in Keto Coffee: The Quick Energy Booster

MCT oil is a concentrated product, not the same thing as coconut oil. The Vandenberghe study notes that MCTs are typically purified from coconut oil. The coconut oil it tested contained 3% C8 and 5% C10, while the classic MCT oil it tested was 55% C8 and 35% C10. The authors conclude that the medium-chain content of coconut oil was only enough to stimulate ketone production modestly.

What Does MCT Oil Add to Your Coffee?

MCT oil adds fat that is readily turned into ketones, which is the reason it is in the recipe. Check the calories and the C8/C10 split on your bottle’s label, because they are not the same for every product.

The main drawback is the gut. The 2021 review says MCTs are safe at doses up to 1 g per kg of body weight, but that gastrointestinal discomfort and diarrhea are common side effects, especially for people who are not used to them. In an older study it cites, three of seven participants had abdominal discomfort and diarrhea after about 23 g of MCT oil. In Courchesne-Loyer’s study, side effects increased with dose: 2 were reported at 10 g of unemulsified MCT oil and 11 at 30 g.

Starting small is the advice in both the company recipe and the research:

• Bulletproof says to start with 1 teaspoon if you are new to MCT oil and build up over several days.
• The 2021 review suggests starting at 5 g and increasing only if there is no diarrhea or other abdominal trouble.
• Courchesne-Loyer’s group reported better tolerance in its longer feeding studies when people started at a low dose and increased it gradually over at least a week.

Butter vs. MCT Oil: Head-to-Head Comparison

Factor	Butter	MCT oil
Why it is added	Creaminess	Ketones
Ketones	Not the fat tested in the studies above	Modest rise; C8 highest in the Vandenberghe study
Energy	About 102 kcal per tablespoon (USDA)	See your product’s label
Main caution	Saturated fat, about 7.2 g per tablespoon (USDA)	Stomach discomfort and diarrhea, more likely at higher doses
Dairy	Yes	No

Who Should Use Butter?

Butter suits you if creaminess matters most and you tolerate dairy. Count its saturated fat against the rest of your day.

Who Should Use MCT Oil?

MCT oil suits you if raising ketones is the goal or you avoid dairy. Build the amount up slowly.

Why Not Use Both?

The Bulletproof recipe uses both: MCT oil for ketones and butter or ghee for body. If you combine them, introduce the MCT oil at a teaspoon first, as the recipe suggests, so you can tell which ingredient your stomach is reacting to.

How to Make Your First Cup of Keto Coffee

The method below follows Bulletproof’s recipe card, with the beginner MCT amount the company recommends.

What You’ll Need

• 8-12 ounces of freshly brewed coffee, made your usual way
• 1 tablespoon unsalted butter or ghee
• 1 teaspoon MCT oil, building up over several days
• A blender, or a handheld milk frother

Step-by-Step Instructions

1. Brew the coffee.
2. Put the coffee, butter and MCT oil in the blender. Hot liquid builds steam pressure in a closed blender, so follow your blender’s instructions for hot liquids. Vitamix, for example, says to let hot liquids cool for 3-5 minutes before adding them and warns that an unvented lid can let pressure build up.
3. Blend for 20-30 seconds, until the drink is frothy and looks like a creamy latte with no film of oil on the surface.
4. Pour and drink it while it is warm.

No blender? Bulletproof suggests putting everything in a large mug and using a milk frother until the drink is mixed and creamy. Stirring with a spoon does not emulsify the fat, so it tends to sit on top.

Frequently Asked Questions

Can I drink keto coffee if I’m not on a keto diet?

Yes, but count it as food. Butter alone adds about 102 kcal per tablespoon by USDA figures, plus whatever the MCT oil adds, and the butter’s saturated fat counts toward your daily total.

Will keto coffee break my intermittent fast?

It adds calories, from the butter and the MCT oil. Whether that counts as breaking a fast depends on the rules of the fasting plan you follow. Plain black coffee is close to calorie-free, as the site’s guide to black coffee and weight loss explains, so if your plan allows only zero-calorie drinks, keep the fats for after the fast.

Why does my keto coffee taste oily or separate after a few minutes?

The fat was not fully emulsified. Bulletproof’s instruction is to blend until there is no film of oil on the surface, so blend for the full 20-30 seconds, or use a milk frother if you have no blender.

Can I use coconut oil instead of MCT oil?

You can, but it is not equivalent. In the Vandenberghe study, the coconut oil contained only 3% C8 and 5% C10, and its ketone peak was 25% of the C8 peak.

Can I sweeten keto coffee?

The Bulletproof recipe has no sweetener. If you add one, check its carbohydrate content, because sugar-free syrups differ in which sweeteners they use. The site’s comparison of sugar-free coffee syrups sets out the sweetener in each one.

Choosing Between Butter and MCT Oil

Butter gives keto coffee its texture, and MCT oil gives it the ketone effect the drink is known for. Each has a cost: saturated fat for butter, and stomach trouble for MCT oil taken too fast. Bulletproof’s recipe card starts with a tablespoon of unsalted butter or ghee and a teaspoon of MCT oil, blended until no oil floats on top; increase the MCT oil only if your stomach handles it. If you have a health condition, talk to your clinician before making it a daily habit.