Does MCT Oil Break a Fast?

Many people use medium-chain triglyceride (MCT) oil to support fat burning and energy levels, but does MCT oil break a fast? Technically, yes–but only slightly.

While MCTs may temporarily shift fat burning from stored body fat to dietary fat, they also provide a ketone boost that can help extend fasting periods and support keto adaptation.

Find out why MCT oil can be beneficial while fasting and learn how to integrate these health-promoting fatty acids into your Healthy Keto® and intermittent fasting plan. 

What are MCTs?

MCTs are medium-length chains of fatty acids found in foods such as palm oil, coconut oil, dairy products, nuts, and seeds.

There are four primary types of MCTs: 

• Caproic acid (C6)
• Caprylic acid (C8)
• Capric acid (C10) 
• Lauric acid (C12)

Each type differs slightly in how quickly it’s metabolized, with C8 and C10 being the most efficient.

Unlike long-chain fats, MCTs have a shorter carbon structure. This allows them to bypass the typical digestive process requiring bile and enzymes for breakdown. Instead, they’re directly absorbed into the bloodstream and quickly converted into ketones by the liver.

Ketones are energy-efficient molecules synthesized during the breakdown of fat. Compared to glucose, they provide a cleaner and steadier fuel source that doesn’t cause insulin spikes and generates fewer free radicals, making them ideal for sustained mental and physical energy.

This explains why MCT oil is a popular tool among those practicing intermittent fasting or following a low-carb diet.

Watch the video below to learn if MCT oil will break a fast.

What is MCT oil?

MCT oil is a concentrated source of MCTs, typically extracted from coconut or palm oil. 

Unlike whole-food sources such as dairy or unrefined coconut oil, which also contain long-chain triglycerides, MCT oil contains only isolated medium-chain fats. 

The high concentrations of fatty acids in MCT oil allow direct and rapid absorption, providing nearly instantaneous energy to the brain and body.

What is intermittent fasting?

Intermittent fasting (IF) is a meal time schedule that cycles between eating and fasting periods, typically with eating windows of 1 to 8 hours. 

Caloric restriction during fasting periods helps maintain steady blood sugar and insulin levels, which pushes the body to shift from burning sugar to using stored fat for energy.

IF is a key part of the Healthy Keto lifestyle, which focuses on combining intermittent fasting with nutrient-dense, low-carb meals.

IF can promote a wide range of health benefits when combined with a nutritious diet, including reduced hunger and cravings and steady energy levels. It also supports cognitive wellness, mood balance, metabolic health, and autophagy which can promote healthy aging and longevity.

Will taking MCT oil while intermittent fasting break my fast?

Because MCT oil contains calories, it will technically break a fast, though the impact is minimal and may be beneficial depending on your health goals.

While MCT oil may temporarily shift your body from burning stored fat to burning dietary fat, it also delivers an immediate source of ketones.

“The ketones derived from MCT oil can help your body adapt to fat-burning more smoothly,” explains Dr. Berg. “It may also support mental clarity, steady energy, and satiety while fasting, potentially helping address common effects of keto flu, including low energy, brain fog, and food cravings.”

That said, once you’re fully fat-adapted, you may not need MCT oil during fasting windows–but it can still be used strategically for an energy boost or workout support. 

However, if your primary goal is weight loss, limiting MCT oil while fasting can help your body tap into its own fat reserves rather than relying on dietary fat for energy. 

Benefits of MCT oil

MCT oil can be a powerful tool to help make your intermittent fasting routine more effective and sustainable.

Here are four ways MCT oil can support your success on a Healthy Keto and intermittent fasting plan.

1. Supports metabolic health

MCTs are associated with fat oxidation and thermogenesis, which may support metabolic function and weight management, especially when combined with intermittent fasting and low-carb eating.

Research published in Pharmacological Research highlights that MCT consumption was linked to increased fat-burning and energy expenditure, and may help promote normal insulin sensitivity.¹

2. Promotes cognitive wellness

MCT oil raises ketone levels, providing an efficient energy source that easily crosses the blood-brain barrier. This can help support mental clarity, focus, and sustained brain energy, especially during fasting or low-carb eating.

Evidence published in the International Journal of Molecular Sciences suggests that enhanced ketone production from MCT oil, particularly while following a ketogenic diet, may promote mitochondrial function and help maintain healthy brain cell activity as the body ages.²

3. Supports energy levels

Unlike long-chain fats, MCTs are immediately absorbed and converted into ketones, which can deliver clean, sustained energy to the brain and muscles. 

Many people find that adding MCT oil to coffee or tea helps them stay energized and focused during fasting periods, supporting both mental clarity and physical endurance throughout the day.

4. Enhances exercise performance

Consuming MCT oil before a workout while fasting can promote endurance, mental focus, and muscle function.

Unlike glucose, ketones are metabolized in the mitochondria without producing lactic acid. This may help promote muscular comfort and energy by minimizing the buildup of lactic acid during intense or prolonged exercise.

MCT oil vs. coconut oil

The biggest difference between coconut oil and MCT oil is their composition. Coconut oil contains a mix of long-chain and medium-chain fatty acids, with about 54 percent of its total fat content consisting of MCTs.

In contrast, MCT is a concentrated extract that contains 100 percent medium-chain triglycerides.

As a result, these two popular oils are metabolized differently. Long-chain fatty acids are more complex and take longer to break down and absorb, slowing their conversion into usable energy.

MCTs don’t require the same breakdown for absorption and provide quick access to ketones, which can be immediately utilized as an alternative energy source.

How much MCT oil should you have while fasting?

Always start slowly and increase intake gradually, as taking too much MCT oil too quickly may cause digestive discomfort or abdominal cramping.

Start with half a teaspoon of MCT oil to give your body time to adjust. Gradually increase the amount over several days, aiming for up to one tablespoon at a time and, if well tolerated, as much as four tablespoons per day.

If you are generally lean and want to maintain your weight level, you can use up to four tablespoons of MCT oil daily. 

However, MCT oil is calorie-dense and will temporarily slow the burning of body fat, so for weight management, you should lower your MCT oil intake after keto-adaptation.

How to use MCT oil on keto

MCT oil is incredibly versatile and easy to incorporate into a Healthy Keto lifestyle.

Because it’s odorless and flavorless, it can be taken straight by the spoonful, especially if you experience hunger or cravings during fasting.

Including MCT oil in protein smoothies, salad dressings, or sauces is an excellent way to boost their nutritional value and can enhance the absorption of fat-soluble nutrients such as vitamins A, D, E, and K.

While it works well as a light cooking oil, it’s crucial to keep the temperature below 320°F (160°C) to prevent oxidation.

Taking MCT oil 30 minutes before a workout may help support exercise performance. MCTs are rapidly absorbed, which can help quickly supply your muscles with energy and may promote endurance.

According to research published in Phytochemistry Reviews, MCTs are most effective when consumed after an overnight fast and paired with a low-carb meal.³ 

Additionally, the authors note that combining MCTs with caffeine may boost the ketogenic response, while emulsifying MCTs can enhance their effectiveness in promoting ketosis and help minimize potential side effects.

This explains why keto coffee, also known as bulletproof coffee, is a popular choice among those practicing intermittent fasting and carbohydrate restriction.

MCT oil coffee recipe

This creamy keto coffee is a delicious way to support fat-burning and boost your energy, without the carbs or sugar common in traditional lattes.

Total time: 5 minutes 

Servings: 1 

Per Serving: 230 calories, 25 g fat, 0 g protein, 0 g carbohydrates 

Ingredients 

1 cup black coffee, brewed

1 to 2 teaspoons MCT oil

1 to 2 tablespoons grass-fed unsalted butter

Instructions

1. Combine coffee, MCT oil, and butter in blender.
2. Blend on high for 20 to 30 seconds until mixed well.
3. Pour into mug and enjoy!

Add cinnamon, vanilla extract, cocoa powder, sea salt, or chili powder for added flavor and nutrition that won’t interrupt your fast.

Key takeaways

Does MCT oil break a fast? Technically, yes, but it has minimal effect on insulin levels and is unlikely to interfere with the metabolic benefits of intermittent fasting for most people.

MCT oil may help extend your fasting window by potentially reducing cravings and supporting energy levels. It’s also associated with mental clarity and fat-burning, and may help support normal blood sugar levels, making it a helpful tool for fasting and keto adaptation.

Flavorless and versatile, MCT oil can be added to coffee, tea, or low-heat meals. Start with a small amount and increase gradually to allow your digestive system time to adjust.

FAQs

Sources

1. https://www.sciencedirect.com/science/article/abs/pii/S104366180900276X ?
2. https://www.mdpi.com/1422-0067/22/22/12310 ?
3. https://link.springer.com/article/10.1007/s11101-024-09969-1#Sec28 ?