A: Hey, Kenny! This is a great question. And as concise as it is, it’s not quite so simple to answer. So, let’s unpack it a bit.

Believe it or not, this question—and variations of it—is one of the most frequently asked questions when it comes to intermittent fasting. “Does ‘x, y, or z’ break a fast?” Kinda funny that one of the first questions people ask about fasting is what can they can get away with (putting in their mouths), isn’t it?

Here’s the deal: If you put anything in your mouth that’s not water—calorie-containing or not—it technically breaks the fast.

There are, of course, some nuances. And I think the real question starts with what you’re trying to get out of fasting. Here are a few things to consider, some of which get completely overlooked:

• Autophagy. If you’re turning to intermittent fasting to upregulate autophagy, which essentially involves “cleaning up” cellular garbage, I’d lean toward consuming nothing other than water. This is especially true if you’re opting for time-restricted feeding, which doesn’t involve terribly long periods of fasting.
• Circadian rhythms. “Meal times have more effect on circadian rhythm than dark and light cycles,” according to Dr. Satchin Panda, leading researcher on circadian rhythms, which regulate appetite, GI function, nutrient absorption, hormone secretion, enzyme activity, and more. In simple terms, even if you’re not consuming calories, carbs, other nutrients, or even other non-suspecting low- or no-calorie compounds (e.g., no-calorie sweeteners, herbal extracts), one could make the argument that doing so wakes up certain organs (e.g., liver, pancreas)—effectively starting the body clock. That’s not necessarily a bad thing. It’s just something to keep in mind.
• Spirituality. Although often overlooked, the benefits of fasting transcend well beyond the physical realm. There are game-changing mental, emotional, and spiritual benefits that can be realized. Many find fasting is a liberating experience that frees them from the emotional shackles of food. When going deeper into a fast (24 – 48+ hours), folks often report never-before-experienced mental clarity and energy.

With those generalities out of the way, let’s talk MCTs, aka medium-chain triglycerides. Even though they technically break a fast, the potential benefits MCTs can offer may outweigh any potential downsides, particularly in the context of intermittent fasting. Let’s unpack those benefits.

4 Benefits of MCT Oil

1). MCTs are like a fasting “cheat code.” The health benefits of intermittent fasting seem to hinge on caloric restriction and ketone production. And MCTs may help support both. In the case of the former, if you’re still restricting calories, then it’s likely benefits will ensue.

In the case of the latter, the body ramps up ketone production in response to depletion of carbohydrate stores (i.e., liver glycogen) and carbohydrate restriction (i.e., low, stable blood glucose levels). Essentially, if you’re not consuming carbohydrate (or a meaningful amount of protein) during the fasting window, then it seems it wouldn’t have a negative effect.

MCTs are healthy, functional fats, so they don’t violate these rules. Having said that, MCTs may spare liver glycogen (i.e., they may be burned preferably over your liver’s stored carbohydrate). In that sense, they may hinder the body’s ketone production.

2). MCTs may help accelerate the transition to fasting. For many people, going from “normal” eating to time-restricted feeding or even more intensive forms of fasting can be a monumental challenge—mentally and physiologically. MCTs may aid the transition in more ways than one.

For starters, MCTs may help support metabolic flexibility and help flip the metabolic switch (more below). Practically speaking, many people who are predominantly “sugar burners” have a stubborn metabolism that struggles to shift into “fat-burning” gear. Many report that using MCTs can help encourage that healthy metabolic flexibility.

Additionally, for those folks who have trouble digesting the notion of fasting, using MCTs can help quell concerns and provide a nutritional bridge during the fasting period. In other words, MCTs can be a crutch to help people realize they’ll be okay without food for longer periods than they’re used to.

3). MCTs may help flip the metabolic switch. As mentioned in both points above, a key physiological outcome of fasting is the body’s shift from relying heavily on burning sugar for fuel to preferentially using fat and fat-derived byproducts called ketones, which are also key signaling molecules in addition to being an efficient form of fuel.

Researchers refer to this as “flipping the metabolic switch.” It explains “the body’s preferential shift from use of glucose to fatty acids and fatty-acid derived ketones.” MCTs (and one MCT in particular, known as caprylic acid, or C8 for short) fit into the equation because the body preferentially converts them into ketones. In other words, we may help flip the metabolic switch by increasing ketone levels.

4). MCTs may help enhance the effects of fasting. In addition to enhancing ketone levels, MCTs may also support caloric restriction, which is another key player in driving the benefits of intermittent fasting. For example, studies have shown that MCTs increase satiety, reduce appetite, and decrease total caloric intake. In that regard, if using MCTs during the fasting period results in a net negative energy intake, it seems like a win-win, particularly if you’re interested in weight loss.

Does MCT Oil Break a Fast? Here’s a Recap

At the end of the day, Kenny, the take-home point is this: Consuming MCTs (or any other non-water item) technically breaks the fast. However, that isn’t necessarily a bad thing, as the calculated use of MCTs offers tremendously positive practical significance.

Having said that, if the main objective revolves around autophagy or spirituality, then I’d lean toward not consuming anything besides water. Even in those cases, because the fasting periods may be longer overall, there may be application of MCTs in the early hours/days to help ease and accelerate the transitory phase.

Hope this helps, my friend!