Ketosis Versus Keto-Adapted

Adaptation to the ketogenic lifestyle doesn’t only mean reaching a state of ketosis. Learn how to tell the difference.

04 Oct, 2020

Article originally published on on 5/31/16. It has been heavily edited for re-publication.

When beginning a new lifestyle, it's common for people to want to know everything about it. Sometimes that means we come across terms with which we are unfamiliar. In regards to the ketogenic lifestyle, one of these terms, that can sometimes throw folks for a loop, is "keto adaptation."

Is It Just Ketosis?

The short answer is no. There is a definite difference between just being in ketosis and achieving the long-term metabolic state we call keto adaptation. It's easy to see, however, why this is such a confusing topic: the terms themselves are similar, and the distinction is not made easier by the common misconceptions that circulate amongst more casual keto practitioners. Let's start at the beginning: what is ketosis? 

Ketosis is a metabolic state wherein your body burns fat for fuel, and produces ketone bodies as a part of the process. There are three types of ketones: acetone, acetoacetate, and beta-hydroxybutyrate (BHB). Ketones are produced hepatically (which is a fancy way of saying "by the liver") as a byproduct of breaking down fatty acids.

That's the simple definition, but there are a few problems with this basic meaning when it comes to the ketogenic lifestyle. First, it's not specific as to how ketosis is attained. That's a problem because, by that definition, long-term starvation or severe/dangerous levels of caloric restriction could both be called ketogenic. If your body goes long enough without food or with very low levels of food, you will produce ketones and be in ketosis. That's obviously not a healthy way to go about achieving your goals.

The second difficulty with this basic definition is that there are no targets. You see, your liver is constantly breaking down fatty acids and creating ketones, but it would be difficult to say that you're constantly "in ketosis" because this process is happening at a fairly low level and your body is still mostly burning glucose for fuel. If you visited your doctor he or she wouldn't consider you as being in ketosis at all until the presence of ketone bodies in your blood and urine were fairly high.

Ketosis and Nutritional Ketosis

When you speak to someone in the ketogenic community about being "in ketosis" they likely mean that the person in question is eating a low enough carbohydrate diet that their body has shifted from burning glucose for energy to burning fat. This is ketosis in the context of the ketogenic protocol. Nutritional ketosis takes the definition a step further. 

Dr. Stephen Phinney, the grandmaster of ketogenic research (along with Dr. Jeff Volek), coined the term "nutritional ketosis." Before Phinney and Volek started doing their work (and challenging almost everything that was considered nutritional orthodoxy), the state of ketosis was associated with two primary situations: starvation and diabetic ketoacidosis, neither of which are particularly relevant to the ketogenic lifestyle as we know it. Dr. Phinney changed the standard paradigm when he coined the term, "nutritional ketosis" and defined it as a body that is in ketosis and has attained it via healthy means (aka, the "nutritional" part). He also provided a lower and upper limit to the definition. According to Phinney, nutritional ketosis is a level of ketone production between 0.5 mmol/dl and 5 mmol/dl. More recently, there has been a lot of discussion within the community about whether or not the presence of any blood ketones at all should "count" as nutritional ketosis. If you're just starting out, however, what you should know is that if you are producing ketones at a level betwen 0.5 mmol/dl and 5 mmol/dl, and have gotten there by eating a nutritive low-carbohydrate diet, then you are generally considered to be well within a state of nutritional ketosis.

What About Keto Adaptation?

Keto-adaption means you are using fat as your primary fuel source. While that seems simple on its face, it doesn't only mean you're in ketosis. It means your body has so adapted to using fat for fuel that it goes to that well first, and becomes incredibly efficient at doing so. Hence, the primary part.

In order for fat to be your body's primary fuel source, a few things have to happen: 

  1. You have to remove glucose/glycogen as an optional fuel source.
  2. You have to produce ketones within the "nutritional ketosis" range.
  3. You have to produce ketones within the "nutritional ketosis" range long enough for your body to switch to fat as your primary fuel source.

When those things happen, you're keto adapted. With keto adaptation typically comes an increase in energy and mental clarity, as well as a return to baseline (and often exceeding it) of athletic and physical performance. Your body is essentially "used to" converting and utilizing fat to fuel your daily activities. This can take as little as a few weeks, to half a year or more, depending on the individual and their level of metabolic health. Athletes and people who are very healthy and fit tend to adapt pretty rapidly. Yo-Yo dieters, people with health problems, and those with known metabolic disorders can sometimes take many months to fully adapt. If you're in one of those latter categories, this does not mean you won't lose weight in the meantime. It simply means that your body may not function at its peak ketogenic level until you're fully adapted.

How Does the Body Adapt to Ketosis?

One major technical reason the keto adaptation process doesn't happen immediately is because of the interplay between the energy needs of your skeletal muscle and your brain. When ketone levels are low, your muscles will use ketones for fuel. As those levels increase, your muscles will burn fat, instead (remember, ketones are byproducts of fat metabolism). Your brain, on the other hand, will use ketones in proportion to the amount present in the blood. In other words, the more ketones in your blood, the less ketones your muscles use (muscles start to use fat, directly, instead of ketones), while your brain uses ketones at a consistent rate in relation to the available supply. When you reach a point where your muscles are using fat for fuel and your brain is using ketones for fuel, you are keto-adapted. This is a process that takes time and is heavily dependent upon the adaptability of your muscles.

Why Adapt?

As stated earlier, reaching keto adaptation means that the initial drop-off many experience in energy, clarity, and athletic performance comes roaring back. Adapting also means your body will be more equipped to handle the occasional unexpected deviation. We live in a society wherein our eating circumstances are not always within our direct control. Pretty much every ketonian has, at some point, been to a restaurant or a friend's house or made a food choice on the fly that resulted in an unplanned "oops." Finding out that you ate something you thought was friendly but was decidedly not can be an unpleasant experience, even when your body is adapted, but that adaptation means it will recover sooner. Instead of starting at square one, well-adapted persons can usually bounce back into ketosis fairly quickly. 

Adaptation also makes experimentation with various aspects of the protocol more amenable to success. Whether you'd like to try fasting, carb cycling, or lower-fat/higher-protein versions of the lifestyle, your body's being well adapted to a ketogenic state makes it much more adaptable otherwise.

The Final Word

As the ketogenic way of eating gains popularity, many diets and health protocols have laid claim to the title "ketogenic." While some may help you achieve the state of ketosis, doing so in a healthy way that will help you sustain long-term health and weight loss benefits is paramount. By following a standard ketogenic protocol, you are more likely to not only reach ketosis, but to do so in a "nutritional" way. Allowing your body the time it needs to fully adapt to maintaining a state of nutritional ketosis is essential to recovery and experimentation. All of which will ultimately help you reach your own Ketogenic Success in the healthiest way possible!


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