Jelmer briefly mentioned in his article about coconut oil, “Something to do with the length of the fatty acid chains, but you, like me, probably don’t understand much about that.” Let me just happen to be an exception because I once wrote an article of over 7000 words on MCTs. In that regard, Jelmer is correct, and it is indeed a quite complex matter.
On the other hand, I am also known for using too many words rather than too few to make something clear. Hence, I will attempt here to both explain what MCTs are and what they can do for you while keeping it somewhat brief and understandable. At least for this part, I will focus on the effects on fat burning, energy provision, and satiety.
What are MCTs?
MCT stands for Medium Chain Triglyceride. Triglycerides are simply fats, a glycerol molecule bound with three fatty acid molecules. Almost all animal and plant fats are triglycerides [1]. The fatty acids with which glycerol is bound can consist of different numbers of carbon atoms, determining their length. Based on the 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, mainly long chains with 12 to 18 carbon atoms are found.
However, this does not mean that all three chains have to be the same length. For example, if two of the three chains are medium in length, it is called an MCT.
This shorter chain length means that despite bearing the somewhat stigmatized name “saturated,” this fat has some 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, resulting in less being utilized as fat storage [4 to 8].
Before long-chain fatty acids (LCTs) enter the bloodstream and can be used as energy, they must undergo a long process. I won’t go through that process this time (emulsified, hydrolyzed, converted into micelles and chylomicrons). It is important to know that it takes six to eight hours, and during those steps, the fatty acids can also be partly stored as body fat [9,10].
MCTs enter the bloodstream immediately after passing through the stomach and being absorbed by the intestine, providing rapid energy and almost no storage 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 through the cell’s inner membrane. In the cell’s power plant, the mitochondria, they are converted into ATP and ketones, ultimately providing energy.
MCTs, Fat Burning, and Weight
The faster, more effective absorption would therefore result in less fat storage, but also in reduced appetite. Most studies on this have shown that MCTs actually reduce body fat and weight. A quote I have cited before is 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 noticed 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 by this. Especially since she has also conducted studies that showed no differences regarding MCTs. At least, when it came to body weight and fat percentage. However, in those studies, calorie expenditure and fat burning were higher with MCTs. Even though this did not lead to a reduced body fat percentage yet, one could optimistically think that this effect is yet to occur. My main objection, however, is that in her studies, 40% of the calories in the diet came from fats, whether MCTs or LCTs. Normally, you want to get 20% to 25% of calories from fats. Forty percent is therefore not representative, but this may have been chosen to more easily understand the different effects of 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 compared to MCTs, and the above-mentioned study that was a bit uncertain (more burning, but not less body fat or weight) against 2 “negative” studies. Three of those six positive studies were from the Canadian researcher. One study showed no difference despite using 40% fats, either 16 grams of olive oil or 16 grams of MCTs [11]. However, the researchers involved point out that olive oil itself is burned more quickly 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 product and not with MCTs, so not really relevant [4,5,6,8,10,11,12,13,14].
Although there are some criticisms, the studies generally seem to demonstrate a positive effect.
Less Hunger with MCTs
Fats in general are said to make you less satiated and therefore feel hungry faster after eating [15,16]. Like the studies showing that saturated fats can have negative effects, these have mainly looked at LCTs and not MCTs. LCTs reduce your appetite just as little as a glass of water or a placebo [17]. Unfortunately, for these types of studies, different fats are often used, so you don’t know the effect of the length of the fatty acid chain. We do know that MCTs reduce appetite in the hours after eating, possibly even longer [18]. Therefore, you can safely include them in your diet if you want to lose weight, but also if you don’t want to gain weight anymore.
However, keep in mind that this does not mean that you should just drink MCT oil if you want to lose weight. The fact is that MCT oil has fewer calories per gram, but more calories per tablespoon than other fats. There are also MCTs in coconut oil. Since coconut oil also consists of LCTs, it does not have the same satiating effect as MCT oil, but it does have a number of other positive effects, including weight loss [19,20].
Conclusion
MCTs are not just a new hype but have been around for a long time, and many studies have shown that they do indeed help with weight loss. They have a positive effect on fat burning and reduce the feeling of hunger. You should not see them as a replacement for all fats in your diet, but as a beneficial addition.
I hope this helps you to better understand the concept of MCTs.
1. https://www.ncbi.nlm.nih.gov/books/NBK234014/
2. https://pubmed.ncbi.nlm.nih.gov/1819831/
3. https://pubmed.ncbi.nlm.nih.gov/1577980/
4. https://pubmed.ncbi.nlm.nih.gov/10435134/
5. https://pubmed.ncbi.nlm.nih.gov/11880549/
6. https://pubmed.ncbi.nlm.nih.gov/18326600/
7. https://pubmed.ncbi.nlm.nih.gov/23651522/
8. https://pubmed.ncbi.nlm.nih.gov/23632752/
9. https://pubmed.ncbi.nlm.nih.gov/22519434/
10. https://pubmed.ncbi.nlm.nih.gov/27129075/
11. https://pubmed.ncbi.nlm.nih.gov/11880549/
12. https://pubmed.ncbi.nlm.nih.gov/12532160/
13. https://pubmed.ncbi.nlm.nih.gov/22569085/
14. https://pubmed.ncbi.nlm.nih.gov/18296368/
15. https://pubmed.ncbi.nlm.nih.gov/17416292/
16. https://pubmed.ncbi.nlm.nih.gov/11158939/
17. https://pubmed.ncbi.nlm.nih.gov/17826170/
18. https://pubmed.ncbi.nlm.nih.gov/18326600/
19. https://pubmed.ncbi.nlm.nih.gov/19437058/
20. https://pubmed.ncbi.nlm.nih.gov/26940344/
