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Last updated: October 29, 2026 · By Martin Smith · How I research
Coconut oil and MCT oil are often talked about as if they were the same thing, especially on keto. They aren’t. This guide explains what MCT oil is, how it differs from ordinary coconut oil, what the studies say about MCT oil on keto, and the side effects to know about before you try it.
The short answer: MCT oil is a concentrated supplement made mainly of two medium-chain fats, C8 and C10. Coconut oil is a cooking fat that contains only small amounts of those two; its main fat is lauric acid (C12), which the body handles more like a long-chain fat. So research on MCT oil doesn’t carry over to coconut oil, and coconut oil raises LDL (“bad”) cholesterol more than other plant oils.
What is MCT oil?
MCT stands for medium-chain triglycerides: fats built from fatty acids with 6 to 12 carbon atoms. MCT oil supplements are made mainly of two of them:
- C8 (caprylic acid)
- C10 (capric acid)
They’re usually separated out of coconut or palm kernel oil. Because these fats are shorter than the long-chain fats in many foods, they’re absorbed quickly and travel straight to the liver, where they’re used for energy (Harvard Nutrition Source). Some of them are turned into ketones there, which is why MCT oil is popular on keto.
Coconut oil vs MCT oil: the key difference
The fats they contain. Roughly half of the fat in coconut oil is lauric acid (C12) (Harvard Nutrition Source; Ghani et al., 2018). The coconut oil used in one study contained only about 3% C8 and 5% C10, the two fats that make up MCT oil (Vandenberghe et al., 2017).
How the body handles them. Lauric acid sits between medium- and long-chain fats, and it behaves partly like both. Reviewers warn that research on pure MCT oil can’t be applied directly to coconut oil (Wallace, 2019). Harvard’s nutrition department goes further: lauric acid “is not an MCT” and is absorbed more slowly and processed like other long-chain fats (Harvard Nutrition Source).
Ketones. In a small study of 9 healthy adults who took two doses of different oils in one day, pure C8 raised blood ketones the highest. Coconut oil’s peak was only about a quarter of C8’s (Vandenberghe et al., 2017). Another small study, in 15 young women, found that both coconut oil and an MCT oil raised ketones more than a long-chain oil did (Furuta et al., 2023). So coconut oil isn’t zero, but if raising ketones is your aim, the evidence points to C8-rich MCT oil rather than coconut oil.
Cholesterol. A review of 16 trials found that coconut oil raised LDL cholesterol more than non-tropical vegetable oils such as olive or sunflower oil. It didn’t change body fat, blood sugar or inflammation markers compared with those oils (Neelakantan et al., 2020). The American Heart Association advises replacing saturated fats like coconut oil with unsaturated fats to lower LDL and heart disease risk (Sacks et al., 2017). In MCT oil trials, blood lipids didn’t change compared with long-chain fats (Mumme and Stonehouse, 2015), but those trials were short.
MCT oil and keto
On a keto diet, your body makes ketones from fat because carbohydrates are kept very low. MCT oil can raise ketones a little even without strict keto:
- Mild ketosis on a normal diet. In 8 healthy adults who took MCT oil four times a day for four weeks, building up the amount over the first week, ketones rose mildly and stayed raised during the day. The researchers reported no side effects in this small group (Courchesne-Loyer et al., 2013).
- Big differences between people. In a study of 25 people, including healthy adults over 65, ketones rose with larger doses of C8 oil. But the response varied a lot from person to person and from day to day, and it was affected by body fat and by what people had eaten beforehand. Age didn’t explain the differences (Juby et al., 2021).
What about weight loss? A review of 13 trials found that swapping long-chain fats for MCTs led to modest reductions in weight and body fat. The authors also found signs of commercial bias and asked for larger independent studies (Mumme and Stonehouse, 2015). A 2024 review in people with overweight or obesity found a small effect for diets with pure MCT oil, but not for oils that mix medium- and long-chain fats (He et al., 2024). In these trials MCT oil replaced other fats; it wasn’t added on top. Adding spoonfuls of oil to your usual diet adds calories.
If you’re interested in other ways people try to raise ketones, my guide to BHB salts covers the ketone supplements sold for keto.
MCT oil side effects and who should be careful
Stomach problems are the main side effect. A review of MCT oil studies found that side effects were mainly stomach discomfort and diarrhea, and recommended starting low and increasing gradually (Lin et al., 2021). In a two-week trial in healthy older adults taking 30 g of an MCT product a day, diarrhea was the leading side effect, affecting three in four people. The side effects were mostly mild to moderate, but about one in ten people stopped because of them. The same trial found no improvement in memory or thinking (O’Neill et al., 2019).
Talk to your doctor before taking MCT oil if you:
- have a liver condition, because MCTs are processed in the liver
- have diabetes, especially if you take medicine that lowers blood sugar or you’re following a keto diet
- have high cholesterol or heart disease (this applies to coconut oil too)
- are pregnant or breastfeeding
- take regular medicine or have any long-term health condition
How to take MCT oil
- Start small. The review above suggests starting with about 5 g (roughly a teaspoon) and building up slowly (Lin et al., 2021).
- Spread it out. Taking it with food or splitting it into smaller amounts during the day may be easier on your stomach.
- Mix it in. Many people add it to coffee, smoothies or salad dressings. If you’re looking at coffee add-ins, note that Java Burn, which I’ve reviewed, isn’t an MCT product: none of its six listed ingredients is MCT oil.
- Check the label. Look for the C8 and C10 content. A product sold as “coconut oil” or “liquid coconut oil” isn’t the same as MCT oil.
- Count it as part of your fat intake, not extra on top.
Coconut oil vs MCT oil at a glance
| Coconut oil | MCT oil | |
|---|---|---|
| What it is | A cooking fat | A concentrated supplement |
| Main fats | Lauric acid (C12), roughly half; small amounts of C8 and C10 | C8 and C10 |
| How the body handles it | Lauric acid is processed partly like a long-chain fat | Absorbed quickly and taken to the liver |
| Effect on ketones | Smaller than pure C8 MCT oil; still higher than long-chain oils in one small 2023 study | Raises ketones, C8 the highest |
| Cholesterol | Raises LDL more than non-tropical plant oils | No change vs long-chain fats in short trials |
| Main side effects | Higher LDL cholesterol | Stomach upset and diarrhea, especially at higher doses |
| Talk to your doctor first if | You have high cholesterol or heart disease | You have liver disease or diabetes, are pregnant, or take regular medicine |
Practical takeaways
- Coconut oil and MCT oil aren’t interchangeable. Don’t expect coconut oil to do what MCT oil studies describe.
- For heart health, unsaturated oils such as olive or canola oil are a better everyday choice than coconut oil, according to the American Heart Association advisory above.
- MCT oil is a supplement, not a shortcut. Any effect on weight in the trials was modest, and it came from replacing other fats, not adding more.
- If you want to try MCT oil, start with a small amount and talk to your doctor first if any of the conditions above apply to you.
Related reading
- What are BHB salts?: the ketone supplements sold for keto, and their sodium content.
- Leptozan review: a BHB salt supplement I’ve reviewed.
- Java Burn review: a coffee add-in I’ve reviewed.
- Green tea extract for weight loss: what the studies show, and the liver risks of high-dose extracts.
Coconut oil vs MCT oil FAQ
Is MCT oil the same as coconut oil?
No. MCT oil is mainly C8 and C10, while coconut oil is mainly lauric acid (C12) with only small amounts of C8 and C10 (Vandenberghe et al., 2017; Harvard Nutrition Source).
Can I use coconut oil instead of MCT oil on keto?
You can cook with it on keto, but it isn’t a substitute if your aim is raising ketones. In a direct comparison, coconut oil’s ketone peak was about a quarter of pure C8’s (Vandenberghe et al., 2017). It also raises LDL cholesterol (Neelakantan et al., 2020).
What are the side effects of MCT oil?
Mainly stomach discomfort and diarrhea, especially at higher doses or when people start with too much (Lin et al., 2021; O’Neill et al., 2019).
How much MCT oil should I start with?
A small amount, about 5 g (roughly a teaspoon), increased slowly (Lin et al., 2021). Check with your doctor first if you have a liver condition or diabetes, or take regular medicine.
Is MCT oil good for weight loss?
The effect in trials was modest, and it came from replacing other fats with MCTs. The authors of one review also found signs of commercial bias (Mumme and Stonehouse, 2015; He et al., 2024).
Sources
- Tricaprylin alone increases plasma ketone response more than coconut oil or other medium-chain triglycerides: an acute crossover study in healthy adults (Current Developments in Nutrition, 2017)
- Health effects of coconut oil: a narrative review of current evidence (Journal of the American College of Nutrition, 2019)
- Physicochemical properties, antioxidant capacities, and metal contents of virgin coconut oil produced by wet and dry processes (Food Science & Nutrition, 2018)
- The effect of coconut oil consumption on cardiovascular risk factors: a systematic review and meta-analysis of clinical trials (Circulation, 2020)
- Dietary fats and cardiovascular disease: a presidential advisory from the American Heart Association (Circulation, 2017)
- Effects of medium-chain triglycerides on weight loss and body composition: a meta-analysis of randomized controlled trials (Journal of the Academy of Nutrition and Dietetics, 2015)
- The impact of medium-chain triglycerides on weight loss and metabolic health in individuals with overweight or obesity: a systematic review and meta-analysis (Clinical Nutrition, 2024)
- Stimulation of mild, sustained ketonemia by medium-chain triacylglycerols in healthy humans (Nutrition, 2013)
- Assessing the impact of factors that influence the ketogenic response to varying doses of medium chain triglyceride (MCT) oil (Journal of Prevention of Alzheimer’s Disease, 2021)
- The effects of GSK2981710, a medium-chain triglyceride, on cognitive function in healthy older participants (Human Psychopharmacology, 2019)
- The ketogenic effect of medium-chain triacylglycerides (Frontiers in Nutrition, 2021)
- Postprandial fatty acid metabolism with coconut oil in young females: a randomized, single-blind, crossover trial (American Journal of Clinical Nutrition, 2023)
- Coconut oil (The Nutrition Source, Harvard T.H. Chan School of Public Health)
This article is for general information only and isn’t medical advice. Speak to your doctor or pharmacist before starting any supplement, especially if you take regular medicine. See my medical disclaimer.