MCTs for quick energy and less body fat

Jelmer briefly touched on it in his article about coconut oil: "Something to do with the length of the fat chains, but you, just like me, probably do not understand much of that". As it happens, I am an exception to that because I once wrote an article of more than 7,000 words about MCTs. In that respect, Jelmer is right and it is fairly complex material.

On the other hand, I am also known for using too many words rather than too few to make something clear. That is why I will now attempt both to explain what MCTs are exactly and what they can do for you, and to keep it somewhat short and understandable. I will therefore limit myself, at least for this part, to the effects on fat burning, energy supply and satiety.

What are MCTs?

MCT stands for Medium Chain Triglyceride. Triglycerides are simply fats, a glycerol molecule connected to three fatty acid molecules. Almost all animal and plant fats are triglycerides [1]. The fatty acids to which glycerol is connected can consist of different numbers of carbon atoms, which determine their length. Based on this number of carbon atoms in the chain, we distinguish short chains (6 or fewer), medium chains (6-10) and long chains (10 or more). The shortest chain consists of 2 carbon atoms, while the longest chain contains 22 carbon atoms. In nature, long chains with 12 to 18 carbon atoms are most common.

This does not mean, incidentally, that all three chains have to be the same length. If two of the three chains are medium length, for example, it is called an MCT.

This shorter chain length gives this fat, despite carrying the somewhat stigmatized label "saturated", a few special properties.

MCTs and digestion

The length of the chains determines how fats are processed after eating [2]. Medium-chain fatty acids provide fewer calories than long chains, namely 8.3 per gram instead of 9 per gram [3]. More importantly, they provide this energy faster and more effectively, so less is used for fat storage [4 to 8].

Before long-chain fatty acids (LCTs) enter the blood and can be used as energy, they have to go through a long process. I will not go through that whole process this time (emulsified, split, converted into micelles and chylomicrons). What matters is knowing that it takes six to eight hours and that during those steps the fatty acids can also be partly stored as body fat [9,10].

After passing through the stomach and being absorbed by the intestine, MCTs enter the blood immediately, which means they provide energy quickly and almost nothing is stored as body fat. Once they reach the cell, they also reach the cell's power plant faster. Unlike LCTs, MCTs do not need carnitine to pass the inner membrane of the cell. In the cell's power plant, the mitochondrion, they are converted into ATP and ketones, which ultimately provide energy.

MCTs, fat burning and weight

The faster, more effective absorption would therefore lead to less fat storage, but also to reduced appetite. Most studies on this have shown that MCTs do indeed reduce body fat and weight. A quote I have cited before comes from a researcher at McGill University in Canada who has conducted several studies on MCTs [4,5,6,10].

Consumption of MCT oil as part of a weight-loss plan improves weight loss compared with olive oil and can thus be successfully included in a weight-loss diet. Small changes in the quality of fat intake can therefore be useful to enhance weight loss.

- Marie St. Onge

Although I only saw for this article that some of her studies were funded by a company that makes a weight-loss product based on MCTs, her studies do not seem biased because of that. Especially because she herself also conducted studies that found no differences compared with MCTs. At least, when it came to body weight and body fat percentage. In those studies too, however, calorie expenditure and fat burning were higher with MCTs. Even if that did not yet lead to a lower body fat percentage, you could optimistically think that this effect still needs to happen. My main objection, however, is that in her studies 40% of the calories in the diet came from fats, either MCTs or LCTs. Normally you want to get 20% to 25% from fats. Forty percent is therefore not representative, although it may have been chosen to make it easier to see the different effects of the fats. Ultimately, however, we want to know what it actually does for you under normal circumstances.

In summary, I found six studies that saw a positive effect from MCTs, plus the above-mentioned study that was a "doubter" (more burning, but no less body fat or weight), compared with 2 "negative" studies. Three of those six positive studies were by the Canadian researcher. One study showed no difference despite using 40% fats, either 16 grams of olive oil or 16 grams of MCTs [11]. The researchers involved point out, however, that olive oil itself is already burned faster than LCTs, so the differences may be smaller. A second study that saw no effect compared only 3 grams of MCTs with a weight-loss drug and not with MCTs, so that is not really relevant [4,5,6,8,10,11,12,13,14].

Although there are therefore some comments to make, the studies generally seem to show a positive effect.

Less hunger through MCTs

Fats in general are said to make you feel less full and therefore make you feel hungry again sooner after eating [15,16]. As with the studies showing that saturated fats can have unpleasant effects, this has mainly been studied for LCTs and not for MCTs. LCTs reduce your appetite about as little as a glass of water or a placebo [17]. Unfortunately, different fats are often used for this kind of research, so you do not know the effect of the different fats [18].

Relatively few studies have investigated the responses of specific fats and fatty acids on food intake. Furthermore, studies have used different fats and fatty acids making it almost impossible to draw conclusions. However, it is clear that not all fats are equal in their effect on appetite and associated biological processes.

- Rania Abou Samra. "Fat Detection: Taste, Texture, and Post Ingestive Effects."

For MCTs, it appears that they actually reduce appetite. This makes it easier to eat less [19 to 22]. Naturally, that makes losing weight mentally a lot easier.

How many MCTs and when?

That is still difficult to say based on the studies. There is, however, an upper limit to what your gastrointestinal tract can process in a certain amount of time, namely 30 grams per three hours [23]. In practice, this means that stomach and intestinal complaints, especially in the beginning, often determine how much you can take. The tendency to vomit and suffering from diarrhea are not unusual side effects when you take too much. This often determined the maximum dose given to participants in studies. For example, when they received 85 grams of MCTs, performance during cardio declined instead of improving because of stomach complaints [24].

The negative effect of MCT ingestion was associated with increased gastrointestinal complaints (ie, intestinal cramping). These data suggest that large amounts of MCTs (85 g) ingested during prolonged submaximal exercise may provoke gastrointestinal problems leading to decreased exercise performance.

- A.E. Jeukendrup, Universiteit van Maastricht

Apparently, however, it is worthwhile to get a substantial part of your fats from MCTs. In Sri Lanka, where fats mainly come from coconut oil, proportionally 38 to 138 times fewer people die from ischemic heart disease than in other countries. This is the lowest figure worldwide. Coconut oil, the largest natural source of MCTs, contains 86% saturated fats, of which 68% are MCTs [25]. This is suspected to be related to the cholesterol-lowering effect of MCTs.

With 30 to 45 grams per day divided over two or three moments, many people are already close to a recommended daily amount of fats. This of course depends on your total required calorie intake. Suppose you need 3500 kcal per day, of which 25% comes from fats. That is 875 kcal from fats. 875 divided by 2 is 437.5, which could be the number of kcal you want to get from MCTs. As stated, they provide 8.3 kcal per gram. So 437.5 divided by 8.3 brings you to just over 52 grams of MCTs.

If you take the MCTs as a kind of pre-workout, you can choose to take, for example, 15 ml in the morning and 30 ml before training. There should therefore be at least three hours between these moments to prevent stomach complaints because the amount cannot be processed. Complaints can arise faster when MCTs are taken on an empty stomach. I used to mix them into my (cold) Brinta in the morning and with fast carbohydrates before training. Taking MCTs together with carbohydrates provides an additional benefit. This appears to make the burning of the MCTs happen even faster [23,26].

Incidentally, 30 ml is not automatically a "safe dose" for your stomach. It may still need to get used to it. I noticed myself that 30 ml, about two tablespoons, did not go entirely well in the first week. If that fast energy has to exit quickly through the back, you would rather be on your own toilet than the one at the gym (I unfortunately found that out too late). It may therefore pay to start with a maximum of 15 ml, or one tablespoon. Others even advise a quarter tablespoon. In any case, it is smart to wait fifteen to twenty minutes after taking it before leaving the house. Then at least you know how your stomach reacts before you leave the safe harbor of your own toilet.

Natural or synthetic MCTs?

If you want to get MCTs from a natural source, you are, as mentioned, mainly dependent on coconuts. They also occur in smaller amounts in dairy and palm kernel oil. Since the 1950s, MCTs have been synthesized from coconut oil, which means you can get 100% MCTs [25].

This can be more attractive than the natural variant. When taken together, MCTs can work differently than when taken separately [27,28]. The "problem" with mixing MCTs with LCTs in one meal is that researchers do not yet know exactly what influence this has on the burning of both the MCTs and the LCTs. What is certain, however, is that MCTs cannot provide their energy as usual when LCTs are also taken [27]. According to one study, this ultimately makes you burn more body fat, paradoxically, because more ketones are produced [28]. In another study, fewer fats were burned [28]. Different ratios were used in these two studies, so clear conclusions cannot yet be drawn.

However, that concerns total fat burning. If you look at the speed of burning as the priority for an energy supplier before or after training, it seems plausible that you would not want to mix the MCTs with LCTs. Because the MCTs cannot supply their energy to the muscles through the normal route, this delivery is delayed.

Part II: MCTs and glycogen sparing

In a next article about MCTs I will discuss another alleged property, namely that MCTs would spare glycogen (fuel for the muscles), which would reduce muscle breakdown.

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