MCT oil

An easily absorbed fat, taken for weight, appetite and energy on keto diets.

People take it for

Weight and appetite
Ketogenic diets
Mental clarity
Physical activity

A plain-English overview, not advice. Written from published reviews and trials and from what people say in public forums.

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What is MCT oil?

Medium-chain triglycerides, or MCTs, are fats made of shorter fatty-acid chains, mainly eight and ten carbons long (C8 and C10), which the body handles differently from the longer-chain fats in most everyday food. It is sold as an oil that blends C8 and C10, or as a pure C8 (caprylic acid) product, and is also added to some foods and drinks. Because these shorter chains are absorbed and used for energy more quickly than ordinary fats, and can be turned into ketones, it has become popular with people on ketogenic and low-carb diets and with people watching their weight. Trials have tested it on its own and alongside ketogenic diets, most often at daily doses from around 10 g to 30 g.

Why do people take MCT oil?

Weight and appetite

The thinking. MCT oil is absorbed and used for energy more quickly than most other fats, and researchers have linked this to feeling fuller and eating less. That is part of why it turns up in weight-management circles, often compared with coconut oil, which the body handles more like an ordinary long-chain fat.

What research has found. One trial found that a breakfast containing MCT oil left people feeling fuller and eating less at a later meal than the same amount of coconut oil or a plain vegetable oil. Another, in people receiving inpatient care for anorexia nervosa, found that higher daily amounts of MCT raised the appetite hormone ghrelin more than lower amounts did. Research here is still young: a few studies so far, mostly pointing the same way.

Ketogenic and low-carb diets

The thinking. On a very low-carbohydrate diet the body increasingly turns to ketones, made from fat, as a fuel. MCT is turned into ketones more readily than most other fats, which is the idea behind taking it specifically alongside a ketogenic or low-carb way of eating, rather than relying on fat from food alone.

What research has found. A crossover trial in healthy adults found that pure C8, the most ketogenic fraction of MCT, raised blood ketone levels, and that the size of the rise depended on how much carbohydrate was eaten alongside it. A separate six-month trial of a ketogenic MCT drink in people with mild cognitive impairment found a clear rise in ketones, with little overall change across a wider panel of cardiometabolic and inflammatory measures compared with a placebo drink. Studies here point in different directions, so this one is still being worked out; the dose, how long people took it and who took part all seem to matter.

Mental clarity and focus

The thinking. The brain can run on ketones as well as glucose, and MCT is one of the quickest ways to raise ketone levels, so some people take it hoping for steadier mental energy and focus, particularly on a low-carb or ketogenic diet. The same idea has led researchers to test it in older adults and in people with early memory problems, where the brain’s use of glucose can decline.

What research has found. Results have been mixed. In healthy young adults, a few weeks of a C8:C10 blend brought better scores on some attention and memory-style tasks but no change on others; in healthy older adults, a ketone-raising form of MCT brought no clear improvement in cognitive tests. A review of trials in people with mild cognitive impairment or Alzheimer’s disease found a small improvement in general cognitive scores, but not in specific areas such as memory, language or attention. The studies disagree, so this is unsettled: dose, duration and who took part all seem to shift the result.

Physical activity

The thinking. Because the body can turn MCT into a ready source of fuel, some people take it around exercise or everyday activity, on the idea that it gives muscles an energy source that does not depend on carbohydrate stores, alongside its more established role on ketogenic diets.

What research has found. One trial gave healthy older adults MCT oil daily for three months and used scans to see how walking-related leg and hip muscles used glucose. Glucose use in those muscles fell and their density rose in the MCT group, alongside a rise in blood ketones. Few studies have measured this yet, so there is little to go on either way.

What does MCT oil do in the body?

Ordinary fats in food are mostly long chains of carbon atoms, and the body takes its time absorbing and breaking them down. The fatty acids in MCT are shorter, six to ten carbons long, and the body metabolises them more quickly, using them for energy sooner than it would a typical long-chain fat.

That quick route to energy is also a quick route to ketones: the liver can turn MCT into ketones, an alternative fuel that the brain and muscles can draw on alongside, or instead of, glucose. This is the same shift in fuel that happens more broadly on a ketogenic or very low-carbohydrate diet, which is part of why MCT oil is often taken alongside that way of eating. Medium-chain fats have also been studied for their effect on the gut’s community of bacteria and on how the body manages weight.

What do people say about taking MCT oil?

These are anecdotes people have shared, not evidence.

What people like

Most of these threads sit on a diabetes and low-carb forum, so views may lean more sceptical or cost-conscious than a general audience would be.
Several people say MCT oil is more palatable than coconut oil, and that a powdered form is easier to tolerate and dissolves better in drinks.
A few describe a subjective lift in mental clarity or fullness after taking it, though none had measured this against a placebo themselves.
One poster took it specifically around training on a low-carb diet, saying it suited athletic performance better than eating carbohydrate beforehand.

Common complaints

Cost is the complaint that comes up most: several people stopped buying MCT oil because they saw it as expensive for an uncertain benefit.
A recurring view across these threads is scepticism that MCT oil does anything a low-carb diet or plain coconut oil would not do anyway.
A couple of people mention digestive upset, including one describing an unpleasant urgency, when MCT oil was taken in more than a small amount.

How people take it

The commonest way mentioned is stirred into coffee or hot chocolate, sometimes with butter or cream, rather than taken on its own.
More than one poster advises starting with half to one teaspoon taken with food, building up gradually to avoid stomach upset.
Some use an MCT powder rather than the liquid oil, saying it mixes into drinks more easily and sits better on the stomach.
Several people said they use plain coconut oil instead of buying MCT oil specifically, often citing price as the deciding factor.

Read from these public discussions:

MCT Oil....Anybody using it? (Diabetes.co.uk forum, 2017)
MCT Oil (powder) (Diabetes.co.uk forum, 2018)
MCT oil (Diabetes.co.uk forum, 2019)
MCT oil (Diabetes.co.uk forum, 2022)
MCT Oil vs Coconut Oil (T Nation forum, 2017)

What forms of MCT oil are there?

Form	What’s different	Per serving, on products we list
MCT oil (C8 + C10)	A blend of C8 (caprylic) and C10 (capric) fatty acids, in ratios such as 60/40 or 70/30.	not in our price tables yet
Pure C8 (caprylic)	Pure C8 (caprylic acid) alone, without the C10 that a blended oil also carries.	not in our price tables yet

What else is worth knowing about MCT oil?

A review of 33 studies and 1,100 participants found gastrointestinal symptoms, especially diarrhoea, abdominal pain and nausea, were the most commonly reported side effect of taking MCT, with reactions more often moderate to severe at higher doses.
In one trial of a 30 g daily dose, diarrhoea was reported by all participants during an initial short test and by three-quarters of participants during a longer follow-up.
Trials comparing MCT oil directly with other fats found no change in total, LDL or HDL cholesterol, but a small rise in triglycerides.
A trial that compared the two directly found MCT oil more effective than coconut oil at reducing food intake, and rated as more palatable, so the two are not simply interchangeable even though they are often discussed together.

If you take medication, are pregnant, or have a health condition, check with a pharmacist or GP first.

The research behind this page (14 studies)

How much does MCT oil cost?

That depends on the form and the pack, so we work out the price of the same dose of every MCT oil product we can find and rank them.

Compare MCT oil prices per dose