Exogenous ketones vs MCT oil: what to choose and for whom

When the choice is between a ketone drink and a can of MCT oil, the decisive factor is not what is "stronger" but why you need ketosis. The editorial team has put together a practical guide: who benefits from MCTs, for whom exogenous ketones are appropriate, and when both products can safely be skipped.

Where to start the choice

The question "which is better - ketones or MCT" has no universal answer, because these products solve different tasks. Before buying either of them, it is worth honestly answering three questions for yourself: why do I need ketosis, how do I eat now, and how much am I willing to spend. The answers determine whether a supplement is needed at all.

MCT oil is first and foremost a dietary fat with special properties. It is logical to regard it as part of the diet rather than as "sports doping." Exogenous ketones are a short-acting functional product that for a few hours raises the level of beta-hydroxybutyrate regardless of what a person has eaten.

Another factor is expectations. Many buyers hope that ketone drinks will help them lose weight. Studies do not confirm this: exogenous ketones do not accelerate lipolysis, and MCTs add calories. If the main goal is weight loss, the priority remains energy balance, and supplements play at most an auxiliary role.

Finally, it is worth assessing your health. People with diabetes, kidney, liver or pancreatic disease, as well as those who limit salt because of blood pressure, should clear any of these supplements with a doctor. For a healthy adult, both products in reasonable amounts are considered safe.

Who is better suited to MCT oil

MCT oil is best suited to people who already follow a ketogenic or low-carbohydrate diet. For them it is a convenient way to add a fat that is rapidly oxidized and partly converted into ketones. The oil is added to coffee, smoothies, salads or protein shakes; it has no pronounced taste and does not harden in the refrigerator, unlike coconut oil.

The second group is those who want gentle support of ketosis during the transition to a keto diet, when the body is not yet adapted. In the study by St-Pierre and colleagues (2019), different MCTs varied in their effect on ketone levels depending on composition, and products with a high content of caprylic acid (C8) acted most strongly. So when choosing it is worth looking at the composition, not just at the word "MCT" on the label.

MCT oil is also advantageous in terms of price: the cost per serving is much lower than that of ketone drinks. For long-term daily use this is a weighty argument. At the same time, its calorie content makes it less suitable for those who strictly count energy and do not want to increase their diet further.

Practical tips for taking MCT oil as a dietary supplement are as follows:

• start with one teaspoon (about 5 ml) together with food to assess tolerability;
• gradually increase the serving over 1-2 weeks, dividing it into several intakes;
• do not take a large amount on an empty stomach or immediately before intense training;
• choose a product with the stated percentage of C8 and C10 and account for its calorie content in the daily diet.

Who is better suited to exogenous ketones

Exogenous ketones make sense for those who need a fast and noticeable rise in ketone levels without a prolonged diet. These may be people experimenting with ketosis but unwilling to give up carbohydrates, or those going through a difficult period of adapting to keto eating who want to soften it.

Ketone salts are more affordable and more pleasant in taste, but they give a moderate rise in β-HB and contain a lot of minerals. For people who sweat heavily and lose sodium this may even be a plus. For those who have elevated blood pressure or limit salt, on the contrary, it is a significant minus, and the composition on the label must be checked without fail.

Ketone esters are a choice for the few. They provide the highest ketone levels, as shown in the review by Stubbs and colleagues (2017), but they have a sharp taste and a high price. They are used mainly in scientific research and in professional sport as an experimental tool under the supervision of sports-nutrition specialists.

Ketones will not suit those counting on "energy for training instead of carbohydrates." Even in the study by Cox and colleagues (2016), where the effect was positive, ketones were given together with carbohydrates, not instead of them. The ACSM consensus (Thomas et al., 2016) keeps carbohydrates the main fuel for intense exercise.

For athletes: the choice depending on the type of load

For endurance athletes the question of ketones comes up most often. Here the editorial team advises caution. Research results are contradictory: after the optimistic work of Cox and colleagues came the study by Leckey and colleagues (2017), in which a ketone diester worsened the time-trial performance of professional cyclists and caused stomach problems.

If an athlete still wants to try ketones, it should be done only in training, not before an important start, and only as a supplement to the usual carbohydrate strategy. New products on competition day are a classic mistake that can cost the result because of an unpredictable stomach reaction.

MCT oil is practically unsuitable for intake directly during exercise. The review by Jeukendrup and Aldred (2004) showed that the tolerable amount is too small to make a noticeable energy contribution, while larger portions cause digestive upset. MCTs can be used in sport only as part of main meals.

In strength sports and bodybuilding the arguments in favor of either of these products are insufficient today. Protein, creatine and the overall calorie content of the diet have an incomparably greater impact on results than ketone supplements.

How not to make a mistake when buying

The market for ketone products is full of marketing promises, so the label should be read carefully. For MCT oil the main thing is the fatty-acid composition. A product consisting mainly of C8 or a blend of C8 and C10 works differently from an oil high in lauric acid. Powdered MCTs often contain carriers, for example acacia gum or maltodextrin, which changes their properties.

For ketone salts it is important to look at the amount of β-HB in one serving and at the mineral content. It is also worth paying attention to whether the form is stated - D-β-HB or a racemic mixture. Manufacturers rarely spell this out, but it is precisely the D-form that is natural for the body and better studied.

Ketone esters are available on the market in limited supply, and their price is substantially higher. They are worth buying only from trusted manufacturers with transparent information on composition and laboratory testing results. Products of dubious origin without a stated composition are better avoided.

Whatever the choice, it is worth remembering: if you measure ketones with a household ketone meter, it shows only the level of D-β-HB in the blood. Urine test strips measure acetoacetate and become less informative over time on a diet, so they are poorly suited to assessing the effect of supplements.

Editorial conclusions

MCT oil is a sensible choice for those who already eat on a ketogenic or low-carbohydrate principle and are looking for a convenient, affordable source of fat. Exogenous ketones are a product for a short-term rise in ketone levels when a diet is not possible or not planned.

For athletes neither option is mandatory. In endurance sports ketones can be tested cautiously and only as a supplement to carbohydrates; in strength sports, resources are better directed to basic supplements with proven effectiveness.

In any case the choice should start with the goal and state of health, not with advertising. People with chronic diseases should consult a doctor before taking them.

To understand the topic more deeply, we recommend reading our article "Exogenous ketones or MCT oil: what is the difference," as well as articles on the ketogenic diet for athletes and on electrolytes during low-carbohydrate eating.

References

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3. Cox PJ, Kirk T, Ashmore T, et al. Nutritional ketosis alters fuel preference and thereby endurance performance in athletes. Cell Metab. 2016;24(2):256–268.
4. Leckey JJ, Ross ML, Quod M, Hawley JA, Burke LM. Ketone diester ingestion impairs time-trial performance in professional cyclists. Front Physiol. 2017;8:806.
5. St-Pierre V, Vandenberghe C, Lowry CM, et al. Plasma ketone and medium chain fatty acid response in humans consuming different medium chain triglycerides during a metabolic study day. Front Nutr. 2019;6:46.
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