Q: A lot of pros are using ketone esters. Do they really work?

A: Not as well as one would think. Here’s why:

This blog will rely on several new reviews by the academic experts on endurance sports nutrition. These publicized reviews are de facto Position Statements of what we know now.

For decades, strong science and the normal practice of training and running in ultramarathons has focused on hydration and carbohydrates to push human performance to its limits. Here is the consensus of research right now: “Research outcomes suggest that daily dietary carbohydrates (up to 12 g·kg−1·day−1) and multiple-transportable carbohydrate intake (∼90 g·hr−1 for running distances ≥3 hr) during exercise support endurance training adaptations and enhance real-time endurance performance” (Costa et al., 2019).

But this knowledge is not exactly easy to apply in the field – as Costa et al. state: “Whether these intake rates are tolerable during ultramarathon competition is questionable from a practical and gastrointestinal experience.” At First Endurance, we know how challenging it can be to get your nutrition right. That’s why we designed our line to work as a system so there’s no more guesswork about what you should take and when. In fact, another recent review on ultramarathon nutrition (Tiller et al., 2019) lists Sports Drinks (hydration, carbs, electrolytes) as the first Food Suggestion to take during ultramarathons (Table 4, page 11). Costa, et al., recommend carb drinks during ultramarathons (Table 1 on page 5).

Back to ketones. Because getting enough carbs to fuel exercise performance is difficult, other fuel sources can be used to add to, extend, or even replace carbohydrates. Fat and protein metabolites (breakdown products) are the only other practical choice, and both are involved with ketone bodies (aka ketone esters).

Note that a ketogenic diet (high fat diet) is not the same thing as ingesting preformed ketone esters. Let’s look at where the science is right now on ketone bodies and ultraendurance performance.

In theory, adding ketone esters, which normally increase in the bloodstream during exercise, can increase the number of ways to make ATP, which keeps your muscles working and your brain working too. Here is what the experts have distilled so far:

Despite the potential efficacy of other ergogenic aids (e.g., ketone ester, MCTs, vitamins, etc.), there are limited data to support their use, and further research is warranted” (Tiller et al., 2019).

In the world of science-speak, this is not a condonement. It leaves the evidence door slightly ajar in case future studies show something practical and significant (the “we do not want to have egg on our faces” mentality), and for researchers to get funding for more studies.


But if there was big merit in ketone esters during ultramarathons, it would have surfaced with a better evidence rating. We are looking for As, not Cs or Ds. Bs may be helpful in the right settings. This review listed B/C/D ratings for the whole lot of “…other ergogenic aids…” without specifying where ketone esters sat.

Looking a little closer at the human performance publications on ketogenic diets, they have so far flunked out for ultraendurance performance (Evidence statement (category B/C) by Tiller et al., page 7). One crossover study of supplemental ketone esters showed a significant performance enhancement for distance (2% average, P<0.05) after lab cycling for one hour at 75% VO2max, followed by a 30 minute go–as–far-as-you-can period (90 minutes total). (Cox et al., 2016). The amount of ketone bodies ingested was 34 grams, which was 40% of the calories provided (the rest was glucose), compared to 100% of similar calories from glucose. 3/8 subjects showed a notable increase in total meters cycled. While this is encouraging, the exercise setting is different from ultramarathons and may not apply to long exercise time periods. In less controlled, real-life settings, these experimental conditions will probably not be met by most users, which means blunting reproducibility of these findings in real life.

Also, the cost of 34 grams of the ketone ester used ((R)-3-hydroxybutyl (R)-3-hydroxybutyrate ketone ester) is expensive; 12 servings of HVMN ketone ester costs $350.10, or $29.17/serving. Each serving has 25g of ketone ester – which is only 75% of the amount used in the study.

Other studies of ketone ester supplementation and endurance exercise have found significant decreases in performance (Leckey et al., 2017; O’Malley et al, 2017; Prins et al., 2020). It is now apparent that supplementing with ketone esters is not the same as a long-term ketogenic diet for exercise performance (Shaw et al., 2020), and is perhaps even worse than null for performance benefits.

As of right now, adding small amounts (a few grams or less) of some sort of ketoester, along with carbohydrates, is not detrimental during long-term endurance performance. However, trying to replace carbs with ketoesters does not look promising for widespread use in ultramarathons or other long-term endurance efforts.

Too many problems have arisen:
1) High cost per serving ($29.17 for 75% of the amount used in the study)
2) Complexity of usage & dietary practices
3) Stability, supply, taste, gastric tolerability issues
4) Which ketoesters to use?
5) Bulk of human performance studies are not finding improvements in long-term exercise
6) There are downsides I do not want to get into right now for taking high levels of ketoesters/ketoacids that reach to the epigenetic levels of cells that, if persisted, would impair overall health, and of course, exercise performance.

There are a few Laws of Nature that, to me, at best, will always limit use of ketone esters during long-term endurance performance. This is not a fad to follow.

May 12, 2020 — Luke Bucci
Tags: research

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