Let’s get one thing clear right from the start, ketones are not keto. Period.

Now, you might be wondering what exactly do I mean by that?

With all the buzz around the keto diet for fat loss, we are beginning to see a surge of supplements on the market to capitalize on the concept of ketosis by directly selling ketone salt supplements. What’s fascinating is that ketones are only hot, because ketosis is the new hot trend in the dieting world, and it seems that most people do not actually understand how exogenous ketones work, or if it even provides similar effects of nutritional ketosis.

It is easy to be confused about the difference between ketone salts, and nutritional ketosis. In fact, those supplement companies are banking on you not understanding the difference. However, in reality, ingesting ketones is in no way the same as adopting a ketogenic diet.

Today we’re going to be pulling back the curtain on ketones and revealing what these ketone supplement companies really don’t want you to know. If you’ve seen these product on the market or simply want to clear up the confusion between ketones and ketosis, then you need to read this article...


Ketones vs Keto

As discussed in last week’s ketosis summary, the sole proven benefit of a ketogenic diet is weight loss, specifically fat loss. The concept comes from depriving the body of carbohydrates, forcing the body to convert the stored fatty acids into ketones, so that they can be burned by the other tissues in the body. In essence, you eat less so your body burns more.

So, if the entire purpose of keto is to mobilize your own endogenous fat stores through the natural production of endogenous ketones, then why would consuming exogenous ketones have a similar benefit?

The answer is that it would not; it would actually do the opposite. Recall that ketones are produced because available energy sources are low. The consumption of exogenous ketones will effectively reduce the metabolic need to produce endogenous ketones and therefore prevent the primary benefit of ketosis altogether. Because exogenous ketones are an additional external energy source, supplementing with ketones is simply increasing your caloric intake, further preventing any caloric deficit for fat loss.

The only potential for the use of ketones is in conjunction with a ketogenic diet as a dietary fat substitute. It may be common for many keto dieters to have difficulty achieving such a high intake of fat content. Therefore, for the keto dieters who have trouble eating a high fat diet and happen to be at too great of a caloric deficit, supplementing with ketones may act as a surrogate for fat intake. However, it is not true that consuming ketones on a balanced diet would have the same effect of ketosis.


Cause and Effect of Ketosis

The entire point of being in ketosis is that fatty acids are used in the production of ketones which is causing the ketosis. In order to evaluate the state of ketosis, there are a variety of products on the market to test the current level of ketosis and this measurement is often used as a readout for how much fat is being utilized. Achieving nutritional ketosis is therefore a marker of successful keto dieting. However, the actual state of ketosis itself is not causing the fat utilization, it is the fat utilization that is causing the state of ketosis. This distinction is important because when you consume ketone salts, you may measure a level of ketosis, but that type of ketosis has absolutely nothing to do with fat loss!

Supplementary Benefits of Ketone Salts?

By now, you should recognize that ketone salts are in no way related to the fat loss mechanisms of keto dieting, but they are still on the market. This is because when you catch on that they are unrelated to nutritional ketosis, they will still try to sell you on the additional beneficial features of ketone salts.


Fuel Economy

The most popular attribute discussed about ketones is the fuel economy. When analyzed at a biophysics level, it has been observed that ketones can burn at a higher efficiency than glucose alone. While this has in fact been validated to be true, the impact of fuel economy is quite overstated.

Take the example of a fuel efficient, economy car: a small, unpowerful, unimpressive vehicle with the only redeeming feature is that it can last longer between fill ups. This is exactly how beneficial ketones can be for exercise performance.

Completely independent of ketosis, ingestion of ketones will successfully displace some glucose in the bloodstream and cause a measureable increase in ketone oxidation. This can preserve glycogen and keep you energized for longer. Therefore, if you are engaging in a very low-intensity, very long-duration race where onboard energy may in fact be a limiting factor, the consumption of ketones may provide an ergogenic benefit.

With the exception of ultra marathons, ironman races, or the tour de france...etc, fuel is rarely a limiting factor, and thus energy economy is almost never a concern. In fact, when the objective is to exercise for the purpose to burn excess calories, energy efficiency is the opposite of what you want. Who wants to be on the treadmill trying to burn excess calories, when it takes longer to burn them because your ketones are too efficient?


Fuel Preference

There is growing evidence that ketone ingestion can independently affect the preference of endogenous fuel selection toward fat oxidation. This would be the first convincing argument about ketones if it turned out to be true and practical. Unfortunately, relevance of this claim may not be very realistic.

A 2016 research study, published in an extremely high impact journal, conducted a thorough analysis of how exogenous ketones could affect fuel preference. It is important to first recognize that this research studied elite cyclists who tend to have higher levels of intramuscular triglycerides and an increased susceptibility to oxidize fatty acids. Secondly, the dose of ketone ingestion was at 573 mg/kg body weight, representing between 45 g - 50 g of exogenous ketones per dose for the average man. To put this into perspective, this quantity of either ketone acids or ketone salts is so high that it would produce a toxic level of acid or salt in the body. Therefore for the purposes of this study the authors created a novel edible ketone ester for safety precautions. Therefore the results of this study may not be what you can expect with commercial ketone salt products for the non-elite cyclist.

The ingestion of ketones at this quantity was shown to greatly displace carbohydrates in the bloodstream and significantly spare glycogen and reduce carbohydrate metabolism. This process clearly shifts energy metabolism away from glucose but that doesn’t necessarily mean it stimulates fat metabolism a great deal.

Due to the high saturation of ketones in the body, the oxidation of ketones is what takes over rather than endogenous fat oxidation. This was shown during three separate experiments with cycling at 75% maximum power for 60 minutes. In all three trials, there was absolutely no significant increase in fat metabolism at rest or during the hour of exercise when compared to carbohydrate-only or fat-only control groups. In fact ketone-ester ingestion suppressed the release of free fatty acids from adipose tissue that occurs in response to normal exercise.

In a fourth experiment the authors investigated a moderate-intensity (70% VO2max), long duration (2 hours) cycling exercise and showed that ketone ingestion was associated increased intramuscular fat oxidation but still no improvement in free fatty acid release from other tissues.

Evidently, the ingestion of mass quantities of ketones has no acute effect on basal fat oxidation rates, or fat oxidation during high intensity exercise, but appears to have the capability to prolong exercise through increasing intramuscular fatty acid dependence and sparing carbohydrates during low/moderate-intensity, long duration activities. However, this is of course dependent on you ingesting approximately 50 g of ketone ester prior and during exercise.

Bottom Line on Ketones

To clear up any confusion, consuming exogenous ketones are not the same as adopting a keto diet. While it may not be for everybody, a keto diet may or may not be something that benefits you as a method of quick fat loss. There may be potential for the use of ketones in conjuction with a ketogenic diet is as a fat substitute, do not be fooled that consuming ketones will be a way to achieve ketosis that will shed body fat.

Alternatively, if you are looking for a supplement to improve endurance longevity, then maybe a ketone supplement might be something you could try. Although, be cognisant that the research on how ketones can improve endurance is still in its infancy and a lot of data has yet to be uncovered. They certainly are not advisable for any high-intensity exercises and there is also evidence that they may hinder exercise-induced adaptations to endurance activities. However, if you’re interested in their acute effects on endurance performance, the current research has observed approximately a 2% improvement in endurance performance when taking 573 mg/kg body weight prior to, and during exercise.

Lastly, if you think that adding ketones to your diet will help you burn body fat (ie. fat from fat cells), then you are not really understanding the current body of research on exogenous ketones. Adding ketones shifts your body into burning those ketones, and potentially intramuscular triglycerides (if you’re an elite cyclist with high levels of intramuscular triglycerides), but there a complete lack of evidence indicating any body fat loss.

Bottom line, although there seems to be some attractive features for the use of ketones, the research shows no practical evidence for ketones to be beneficial for the purposes of either burning of body fat, or significantly improving exercise performance at this time.

As we await for further research, the big picture of how ketones may become a true ergogenic supplement may change over time. My philosophy is to adapt with the current research, and currently, ketones do not hit the mark yet for me.


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