What MCTs Actually Are (And Why They Got Popular)
Medium-chain triglycerides, or MCTs, are a type of fat that gained rapid popularity in the wellness world for their supposed ability to boost fat burning, enhance mental clarity, and fuel workouts. Unlike long-chain fats found in most foods, MCTs contain shorter carbon chains, typically ranging from six to twelve carbons, which changes how they are digested and used by the body (1).
The four main types of MCTs are:
- C6 (caproic acid)
- C8 (caprylic acid)
- C10 (capric acid)
- C12 (lauric acid)
The shorter the chain, the faster the body absorbs and transports the fat directly to the liver, where it can be converted into ketones. C8 and C10 are the most common in MCT oil supplements because they are most efficiently turned into ketones (2). This unique pathway bypasses the slower lymphatic fat absorption used by longer-chain fatty acids (3).
The promise was simple: “A fat you can eat that helps you burn more fat.”
This marketing pitch exploded during the early keto boom. Popularized by Bulletproof coffee and promoted by influencers as brain fuel and fat-burning oil, MCTs were positioned as a shortcut to ketosis, energy, and weight loss. Coffee with butter and MCT became a trend not because of its nutritional completeness, but because of the promise of feeling full and mentally sharp while supposedly burning fat faster.
But feeling energized is not the same thing as reducing body fat.
The surge in popularity also created confusion. Many people started using coconut oil as a substitute for MCT oil, unaware that lauric acid (C12), the dominant fat in coconut oil, does not behave like true MCTs. While technically medium-chain in length, it is metabolized more like a long-chain fat (4). That means the benefits linked to MCT oil do not necessarily apply to standard coconut oil.
Even within MCT products, quality and composition vary. Some blends contain mostly C8, which produces more ketones and tends to be gentler on digestion, while others include more C10 or even traces of C12, which slow the metabolic benefits and may increase the chance of GI distress (5).
MCTs got their reputation because they absorb quickly and convert to ketones, but that speed does not automatically translate to sustainable fat loss. Energy from MCTs still counts as calories, and the body will burn them before tapping into stored fat. That distinction matters (2).
💡 Key Takeaway: MCTs got popular for their fast-burning properties, but speed of absorption is not the same as sustainable fat loss.
The Metabolic Hype vs. Real-World Results
The most common misconception about MCTs is that they somehow melt away body fat on their own. This belief often comes from the fact that MCTs raise blood ketone levels, especially C8 and C10 oils, which are rapidly converted in the liver into ketones like beta-hydroxybutyrate (6). But producing ketones from dietary fat is not the same as burning stored body fat. Ingesting MCTs may increase ketones, but the source of those ketones is the MCT oil itself, not from your love handles.
This is one of the most misleading sleights of hand in modern diet culture.
MCTs are still calories. They are quickly absorbed and burned, but they can still add to total caloric load and displace other foods that might offer more satiety or nutrient density. If you add MCTs to your diet without reducing calories elsewhere, it becomes fuel the body must burn before accessing fat stores (2).
Clinical studies looking at MCTs and weight loss often involve very short durations, small sample sizes, or tightly controlled calorie-restricted diets where MCTs replace other fats—not simply get added on top (2). When MCTs replace long-chain fats in a low-calorie context, there may be modest benefits to thermogenesis or appetite suppression. But this is not how most people use them.
In the real world, most people pour MCTs into smoothies, coffees, or meals without adjusting anything else. This often increases total caloric load and pushes the body to burn the MCT instead of creating a calorie deficit.
The energy boost people feel from MCTs is real. Because they bypass normal fat digestion, they can be rapidly oxidized for quick fuel, which may lead to mental clarity or reduced brain fog. But that short-term lift should not be confused with long-term metabolic transformation (7).
In some cases, MCTs may even lead to overeating. If they blunt hunger temporarily without supporting satiety or fiber intake later, they can trigger rebound cravings once the rapid fuel is burned off. This is especially common when MCTs are consumed without adequate protein or during long fasts.
💡 Key Takeaway: MCTs may support energy but rarely drive long-term fat loss without dietary precision.
When MCTs Might Actually Help
Despite the hype, MCTs are not useless. They do have niche metabolic applications when used intentionally and with precision.
One of the most studied and practical uses of MCTs is during low-carb transitions. When someone reduces carbohydrates drastically, the body goes through a temporary lag in energy production, often referred to as keto flu. During this period, MCTs can serve as a rapid source of ketones, easing fatigue, brain fog, and low energy while the body adjusts to fat metabolism (8).
Another well-supported use is for neurological energy support. In individuals with cognitive decline, epilepsy, or insulin resistance in the brain (sometimes described as “type 3 diabetes”), ketones from MCT oil may provide a more efficient fuel source than glucose. This is one of the few contexts where ketone production may be beneficial independently of weight loss (9).
MCTs may also help in meals that are very low in fiber and fat, such as protein shakes or collagen drinks, where a small dose of easily absorbed fat enhances calorie absorption or satisfaction. A tablespoon of MCT oil in a low-fat, low-fiber context may stabilize energy or reduce post-meal blood sugar swings—but that only works when the meal is controlled and not already energy-dense (10).
There is also a slight thermogenic effect from MCTs compared to long-chain fats. In tightly controlled research, MCTs slightly increased daily energy expenditure in participants, likely due to their rapid oxidation and lower storage potential. But the margin was small, usually around 100 to 150 extra calories burned per day when MCTs replaced other fats, not when added freely (7,10).
In other words, the benefit is real but it is small and context dependent.
The clients who benefit most from MCTs tend to be those with very specific goals:
- Managing energy in carb-restricted or fasted states
- Supporting cognition under metabolic stress
- Increasing fuel in small meals without fiber or bulk
- Reducing hunger when used as a pre-meal buffer in structured plans
Everyone else is likely just drinking oil.
💡 Key Takeaway: MCTs have specific, narrow use cases but are not magic by default.
The Digestive Catch: When MCTs Backfire
The benefits of MCTs depend heavily on dose, type, and individual tolerance. And for many people, the digestive system is the first place MCTs show their limits.
Medium-chain triglycerides are absorbed rapidly, but that same speed can overwhelm the gut. A common side effect of MCT oil, especially in liquid form, is loose stools, bloating, or even outright diarrhea. These symptoms tend to show up when intake exceeds tolerance, which varies by individual and the specific chain length of the oil used (11).
C8 (caprylic acid) is generally the most tolerable and ketogenic of the MCTs. C10 (capric acid) is slightly slower to absorb and more likely to cause discomfort. C12 (lauric acid) behaves more like a long-chain fat and often contributes to fat malabsorption symptoms when consumed in excess. Many cheap MCT oil blends contain higher amounts of C10 or C12, which increases the digestive burden (2,11).
Clients with IBS, bile acid sensitivity, or small intestinal bacterial overgrowth (SIBO) often find that MCTs trigger bloating, nausea, or cramping. That is because MCTs bypass standard fat digestion, meaning they hit the small intestine quickly and can alter motility or gut-brain signaling. In these individuals, even modest doses can backfire.
Powdered MCTs may be slightly easier to tolerate due to slower release, but they often contain added binders or fibers that create other digestive complications. That means even “cleaner” options come with trade-offs.
Another problem is overpouring. Because liquid MCT oil is tasteless and mixes easily into coffee, smoothies, or broths, it is common to underestimate portions. A tablespoon may become two or three without measuring. This is especially problematic when the person is already eating a high-fat diet, adding MCTs to an otherwise complete meal rather than using them as a strategic replacement.
Finally, it is worth clarifying that coconut oil is not MCT oil. Coconut oil contains mostly C12 (lauric acid) and a blend of longer-chain saturated fats that do not produce the same metabolic or digestive profile. While coconut oil has its place in cooking or skincare, it is not a reliable substitute for the metabolic effects seen in purified C8 or C10 oils (12).
If you feel bloated, gassy, or sprinting to the bathroom after using MCT oil, your gut is not broken. It is giving you biofeedback.
💡 Key Takeaway: If MCTs leave you bloated or sprinting to the bathroom, the signal is clear.
Frequently Asked Questions
Do MCTs actually burn body fat?
Not directly. MCTs are rapidly converted into ketones, which may support energy, but the fat being burned is the MCT oil itself—not stored body fat.
What is the difference between MCT oil and coconut oil?
MCT oil is refined to contain mostly C8 and C10 fatty acids, which absorb quickly and support ketone production. Coconut oil contains mostly C12 (lauric acid), which behaves more like a long-chain fat and is not as effective for ketone generation.
Why do MCTs cause digestive issues for some people?
MCTs bypass traditional fat digestion and hit the small intestine quickly. This can trigger loose stools, bloating, or cramping, especially at higher doses or in sensitive individuals.
Can I use MCT oil while fasting?
MCTs technically break a fast because they contain calories, but they may support energy and mental clarity during intermittent fasting windows. They are best used intentionally, not as an excuse to overconsume fat.
Are powdered MCTs better than liquid?
Powdered MCTs may be easier on digestion for some people, but they often contain additives like fibers or emulsifiers that may cause issues of their own. Always check the ingredient list.
✏︎ The Bottom Line
MCTs are not useless, but they are not magic either. They were marketed as fat-burning fuel, but in reality, they are simply fast-burning fat. For a narrow group of people such as those in deep ketosis, managing neurological issues, or navigating low carb transitions, MCTs may be a useful tool.
For everyone else, they are often just extra calories with a side of digestive chaos.
MCTs are rapidly absorbed and oxidized in the liver, which can overwhelm the digestive system if taken in high amounts or without adaptation. Common side effects include cramping, loose stools, and bloating, especially when added to a mixed or high-carbohydrate diet (2).
If you are working toward fat loss, energy balance, and real metabolic change, start by listening to your gut. Quite literally.
Download our free eBook and learn how to stop falling for trendy fuel that backfires.
Download our free eBook
10 Weight Loss Myths That Are Keeping You Stuck – And How to Break Free
Bibliography
- Bach, A C, and V K Babayan. “Medium-chain triglycerides: an update.” The American journal of clinical nutrition vol. 36,5 (1982): 950-62. doi:10.1093/ajcn/36.5.950. https://pubmed.ncbi.nlm.nih.gov/6811460/
- St-Onge, Marie-Pierre, and Peter J H Jones. “Physiological effects of medium-chain triglycerides: potential agents in the prevention of obesity.” The Journal of nutrition vol. 132,3 (2002): 329-32. doi:10.1093/jn/132.3.329. https://pubmed.ncbi.nlm.nih.gov/11880549/
- Babayan, V K. “Medium chain triglycerides and structured lipids.” Lipids vol. 22,6 (1987): 417-20. doi:10.1007/BF02537271. https://pubmed.ncbi.nlm.nih.gov/3112486/
- McCarty, Mark F, and James J DiNicolantonio. “Lauric acid-rich medium-chain triglycerides can substitute for other oils in cooking applications and may have limited pathogenicity.” Open heart vol. 3,2 e000467. 27 Jul. 2016, doi:10.1136/openhrt-2016-000467. https://pubmed.ncbi.nlm.nih.gov/27547436/
- St-Pierre, Valérie et al. “Plasma Ketone and Medium Chain Fatty Acid Response in Humans Consuming Different Medium Chain Triglycerides During a Metabolic Study Day.” Frontiers in nutrition vol. 6 46. 16 Apr. 2019, doi:10.3389/fnut.2019.00046. https://pubmed.ncbi.nlm.nih.gov/31058159/
- Vandenberghe, Charlotte, et al. “Medium Chain Triglycerides in Sports Nutrition: Metabolic and Performance Effects.” Current Opinion in Clinical Nutrition and Metabolic Care, vol. 20, no. 4, 2017, pp. 279–285. https://pubmed.ncbi.nlm.nih.gov/28505002
- Croteau, Etienne et al. “Ketogenic Medium Chain Triglycerides Increase Brain Energy Metabolism in Alzheimer’s Disease.” Journal of Alzheimer’s disease : JAD vol. 64,2 (2018): 551-561. doi:10.3233/JAD-180202. https://pubmed.ncbi.nlm.nih.gov/29914035/
- Skartun, Oddbjørn et al. “Symptoms during initiation of a ketogenic diet: a scoping review of occurrence rates, mechanisms and relief strategies.” Frontiers in nutrition vol. 12 1538266. 26 Mar. 2025, doi:10.3389/fnut.2025.1538266. https://pubmed.ncbi.nlm.nih.gov/40206956/
- Fortier, Mélanie et al. “A ketogenic drink improves brain energy and some measures of cognition in mild cognitive impairment.” Alzheimer’s & dementia : the journal of the Alzheimer’s Association vol. 15,5 (2019): 625-634. doi:10.1016/j.jalz.2018.12.017. https://pubmed.ncbi.nlm.nih.gov/31027873/
- Wijaya, D., Wihadmadyatami, H., et al. “The Effect of Supplementation of Emulsified Medium-Chain Triglycerides and Isomalto-Oligosaccharides on Ketone Production and Appetite in Rats.” Clinical Nutrition Open Science, vol. 36, 2021, pp. 43–51. https://www.sciencedirect.com/science/article/pii/S2667268521000218
- Liu, Yeou-mei Christiana, and Huei-Shyong Wang. “Medium-chain triglyceride ketogenic diet, an effective treatment for drug-resistant epilepsy and a comparison with other ketogenic diets.” Biomedical journal vol. 36,1 (2013): 9-15. doi:10.4103/2319-4170.107154. https://pubmed.ncbi.nlm.nih.gov/23515148/
- Norgren, Jakob et al. “Ketosis After Intake of Coconut Oil and Caprylic Acid-With and Without Glucose: A Cross-Over Study in Healthy Older Adults.” Frontiers in nutrition vol. 7 40. 15 Apr. 2020, doi:10.3389/fnut.2020.00040. https://pubmed.ncbi.nlm.nih.gov/32351966/
