MCT + Chili Make a Pretty HOT Pair: 50% Increase in Diet Induced Thermogenesis in Well-Controlled Human Trial

If you like chili oil, go for it, otherwise perform the reality check before ruining your taste-buds.
While the word "thermogenic" still carries much weight in the world of the average fitness maniac, SuppVersity readers like yourself should know better than to go crazy over rodent study #1021412 showing "potent thermogenic effects" when an extract from an exotic herb in Dr. Oz garden was administered once in an equivalent dosage that would require you to ingest the whole package of the corresponding "brand new, revolutionary" fat burner that's marketed by the said study.

Human study + no exotic herbs - so does it work?

Well with the study at hand, things are somewhat different. Firstly, the experiment Miriam E. Clegg, Mana Golsorkhi and C. Jeya Henry conducted was done with human, not rodent "subjects". Secondly, the "supplements" they used were no exotic herbs from Dr. Oz Garden or whatever remote region in the Himalaya they were simple MCT oil & Chilis - 20g of 30g of a hot chilli spice blend (Gourmet garden, Northampton, UK), to be precise the former and 30g of. And thirdly, the a +50% increase in diet induced thermogensis could actually make a difference - in the very long term and if you are using it on top of a energy restricted diet.
Figure 1: Macronutrient composition of the iso-caloric test meals; *due to the lower energy density of long-chain triglycerides, only 18.4 g of sunflower oil was used to match the energy content of the meals (Clegg. 2013)
In a randomized controlled fashion, the subjects, 7 healthy volunteers (6f 1m; 25.7±3.6 year;
1.69±0.09 m; 62.5±7.5 kg) who had reported fasted to the lag in the morning of the testing days, consumed a standardized English breakfast consisting of  consisting of an egg omelet, tomato, mushroom, sausage, bacon, toast and some "good old" orange juice.
Suggested read: "Capsaicin - 2.56mg to Keep Your Metabolism Running on a Diet. Cold Thermogenesis - 5°C for 6kcal/h. Mobile Phones - 0.853 W/kg Pulsed EMR to Mess Up Neuro-transmitters" | read more
"The cooked breakfast was prepared with chilli and MCT oil, chilli and sunflower oil, bell pepper and sunflower or bell pepper and MCT oil added to the omelet.

Glucose was added to chopped bell pepper to give it a similar macronutrient and energy cost as the chilli mix. The chilli mix consisted of 60 % chilli (cayenne, habanero). The capsaicin content of the chilli blend was estimated about 2,000 ppm capsaicin (based on information provided by the manufacturers). According to this, the 30 g chilli blend added to breakfast meal was comparable to the amount of chilli used (30 g) in earlier studies to assess the effect of chilli on metabolic parameters." (Clegg. 2013)
The resting metabolic rate of the subjects had been deterimned before breakfast, while the diet induced thermogenesis (DIT) was quantified for 15 minutes they "broke their fast" (learn more about "breaking the fast" here) and then every 30 min within the following 6h.
Suggested read: "Are You Still Burning Calories or Already Losing Fat? Study Shows: 5x15 Min HIIT Reduce Body Fat & Improve Fitness Twice as Effectively as 5x40min of Classic Cardio" | read more
"The energy expenditure increased postprandially following all four breakfasts reaching a peak in the chilli–sunflower oil and pepper–sunflower oil at 1 h and at 2 h in the chilli– MCT oil and pepper–MCT oil, respectively. [...]

There were significant differences in total DIT and percentage DIT between the different breakfast meals (P=0.003). [...]

Chilli–MCT had the highest EE, and pepper–sunflower oil had the lowest. It was noted that the increased energy expenditure occurred between 2 and 6 h postprandially; analysis of these data alone substantiated the results above.
Interestingly, the rate of fatty acid oxidation did not vary significantly. Well, with one exception: The difference between the contribution of fats to the total energy expenditure was significantly different for the pepper–sunflower oil and pepper–MCT oil (P=0.032) trials. Similarly, the meal induced elevation in carbohydrate expenditure was more pronounced in the +MCT trials than in the + sunflower oil trials, but neither of these effects resulted in measurable differences in terms of satiety, hunger, fulness or prospective food consumption, which were all identical across the groups.

Real-world Significance and the Theory of Relativity

The same goes for symptoms of gastrointestinal distress, which is something that's actually a little surprising. After all, both MCTs and chili have been described as potential gut irritants in certain populations, yet none of the participants appeared to suffer more during the corresponding testing conditions.
Figure 2: Ratios are important, but total increases in energy expenditure of max. 12kcal are simply laughable (Clegg. 2013)
So, we do have a side-effect 50% increase in diet-induced thermogenesis? Awesome... well, you look at the absolute value of post-prandial energy "wasting" in response to the selection of the "right" oils and take into consideration that a previous study showed that the "fatty oxidation bonus" from MCTs vanish over time (learn more), it remains questionable, whether even these, allegedly pronounced increases in diet-induced thermogenesis will do anything.

Remember: "The only consistent finding among [fat loss trials on both ends of the low vs. high carb spectrum] is that adherence - the degree to which participants continued in the program or met program goals for diet and physical activity - was most strongly associated with weight loss." (Pagato. 2013)
Bottom line: Personally, I don't think it's worth to spice up your food with "MCT + chili" - unless, of course, you like it this way. If that's the case the extra 12kcal of energy expenditure are something I believe few of you will mind.

If, on the other hand, you are just telling yourself that you like your food with chili and MCTs, you should not be wondering that all your past weight loss efforts have sucked. If there is anything that really messes with weight loss success, it's not low postprandial thermogenesis, but not sticking to one's diet; and if the food you eat does not only contain less energy than you want, but also tastes like fiery crap, falling off the wagon and not achieving your fat loss goals is almost guaranteed; and if that happens your relatively large (~50%), but in absolute terms already irrelevant increase in daily energy expenditure is not going to help you.

  • Clegg ME, Golsorkhi M, Henry CJ. Combined medium-chain triglyceride and chilli feeding increases diet-induced thermogenesis in normal-weight humans. Eur J Nutr. 2013 Sep;52(6):1579-85.
  • Pagato SL, Appelhans BM. A Call for an End to the Diet Debates. JAMA. 2013;310(7):687-688.
Disclaimer:The information provided on this website is for informational purposes only. It is by no means intended as professional medical advice. Do not use any of the agents or freely available dietary supplements mentioned on this website without further consultation with your medical practitioner.