What is the Ketogenic Diet?

What is the Ketogenic Diet?

Are you unsure of what exactly the ketogenic diet is and how it works? Does talk about carb counts and ketones sound confusing? Are you looking for a diet to help you achieve the physique and health you’ve always wanted? If you answered yes to any of those questions, then you’re in the right place. I’m going to walk you through what the ketogenic diet is, and what it does to your body. I’ll also go over why the ketogenic diet is safe for most people. Lastly, we’ll go over a few variations on the ketogenic diet and if they might be right for you.

Keto: plain and simple

Simply put, the ketogenic diet is one that allows your body to enter into a state of ketosis. Your body enters into ketosis when you restrict the number of carbohydrates you consume. When your body is in ketosis it is largely using fat for energy.

There it is. If you read the three sentences in the above paragraph, you now understand more about the ketogenic diet than most people. In fact, let me make it even simpler:

If you don’t eat carbs, your body burns fat.

That is the ketogenic diet defined in one sentence. There are a few different fuel sources your body can burn for energy. The two main sources are carbs and fats. When you have a diet where carbs are plentiful, then carbs will be your bodies main energy source. That’s simple enough. If you eat carbs your body is going to burn carbs. But, if you significantly reduce the number of carbs you eat, your body is forced to turn elsewhere for energy sources. Your body’s largest energy reserves are its fat stores, so, that’s where it goes.

The Traditional Ketogenic Diet

The ketogenic diet is nothing new. Traditionally, people all over the world, especially the farther away you move from the equator have eaten low carb diets, at least seasonally, for thousands of years. Furthermore, the ketogenic diet was used to treat epilepsy and seizures in the early 20th century and is still used today in situations where medication and other methods are not effective.

The ketogenic diet is typically regarded as a high fat, moderate protein, and very low carbohydrate diet. The general daily macronutrient calorie percentage breakdowns are 70/25/5. What does that mean? In a given day you should get 70% of your daily calories from fat, 25% from protein and 5% from carbohydrates. Depending on individual goals, those ratios can fluctuate somewhat. Some individuals who are highly active may desire to consume a greater amount of protein. Others, for therapeutic reasons, may wish to drop the protein percentage even lower. There is also, zero carb ketogenic diets whose motto is “eat meat, drink water.” They tend to only eat meat and organs and are sometimes known as the carnivore diet. In those cases, their carbohydrate level is even lower than 5%. If you have a certain calorie goal another way to calculate your desired macros is to calculate the amount of protein you want to consume, add 20 grams carbohydrate allowance for the day and then fill out the rest of your calories from fat.


Regardless of how you choose to decide your macronutrient breakdown, there is one overarching goal of the ketogenic diet. That one goal is actually what makes it a ketogenic diet in the first place. That goal is for your body to remain in a state of ketosis. The metabolic state of ketosis is what separates a ketogenic diet from a simple low carb diet. All ketogenic diets are low carb. Not all low carb diets are ketogenic. Whether or not your body is in a state of ketosis is the deciding factor between the two. But a more practical definition is that a ketogenic diet tends to stick to 20 net carbs or less for the day. You also may hear it defined as an ultra-low carb diet.

The main problem with the term “low carb diet” is that there is no set definition of what that means. The ketogenic diet is clearly defined in the medical, scientific and nutritional literature. “Low carb” can mean whatever the person writing wants it to mean. It’s subjective. I’ve seen low carb defined as less than 30 grams of carbs a day. I’ve also seen the low carb title attached to a diet consuming over 100 carbs a day. With no clear definition of the term, the term becomes useless.

What is Ketosis

If a ketogenic diet is defined by your body being in a state of ketosis, then what does that mean? As I stated above, that means your body is utilizing ketones and fat for fuel. But, what are ketone bodies?

There are three ketone bodies found in the human body: acetoacetate, beta-hydroxybutyrate, and acetone. During periods of prolonged carbohydrate restriction, your liver begins to break down fatty acids into ketones for energy elsewhere in the body. This process is known as ketosis.

Your liver first produces acetoacetate followed by beta-hydroxybutyrate. Acetone is a little different because it is created by the spontaneous breakdown of acetoacetate and is largely exhaled. This is why when someone is starting a ketogenic diet you may pick up a faint nail polish remover smell from their breath. That is because nail polish remover usually contains acetone. Acetone is also what is being measured by devices that analyze your breath to register if you are in ketosis.

Your liver breaks down fatty acids into ketone bodies for use in the mitochondria of cells throughout the body. Ketones are an excellent fuel source. In fact, they are so good that your body stores excess energy in that very same fashion: FAT. However, there are a few types of cells that cannot run off of ketones and instead need glucose to function. For example, red blood cells need glucose to function. Why that is, is unimportant at the moment and will be discussed in future articles. But your body can easily make up the difference through the process of gluconeogenesis. Gluconeogenesis is how your liver can produce the small amounts of glucose your body needs if you’re not eating carbs.

Variations of the Ketogenic Diet

You may hear the acronyms SKD, TKD and CKD thrown around in keto forums and elsewhere. These acronyms stand for Standard Ketogenic Diet, Targeted Ketogenic Diet, and Cyclical Ketogenic Diet. The SKD is what we’ve been discussing so far. The TKD and CKD are largely utilized by athletes and those who engage in heavy athletic activities such as weight lifting or track. Many report losses in athletic performance on the ketogenic diet. The TKD and CKD are attempting to utilize carbs strategically to enhance athletic performance while gaining the benefits of the ketogenic diet at the same time. Some research has shown however that for individuals unaccustomed to a very low carbohydrate diet there can be weeks to possibly months of adaption time for your body. Performance could return once full adaptation to the ketogenic diet has occurred. Some have suggested that approaches like TKD and CKD are a mistake and keep your body from fully adapting. Much of this is just theory. Solid, methodical research done in this area is severely lacking.

Tired Weight LifterThe TKD is designed around the idea that a relatively small amount of carbs around training can either add a performance boost or aid in recovery post workout. The rest of the time the individual follows a ketogenic diet. On days where no intense training occurs, no training carbs are consumed. As for training carbs, between 25 and 50 grams is the number most people use. The goal of these carbs is to improve performance and recovery by giving a bump to muscle glycogen stores. Many users report benefits from this approach but as said before, research is lacking.

The CKD is similar to the TKD in that carbohydrates utilized in a strategic fashion. However, with the CKD carbohydrates are not consumed around workouts, but rather in one to two days re-feeds. During this “re-feed” large amounts of carbohydrates are consumed to fully restock muscle glycogen stores. For this theory to work muscle glycogen levels must be severely depleted between re-feeds. Heavy and high volume weight training is typically employed in this endeavor. This approach is generally not advised for those not engaged in substantial amounts of heavy training.

Whether or not the Targeted Ketogenic Diet or the Cyclical Ketogenic Diet is worthwhile or beneficial is a discussion for another time and for another article. The point here is to give you a general idea of what each is and why they are sometimes used. There are other variations as well, but this is a good overview.

Ketosis is not Ketoacidosis

It’s important to note that ketosis and ketoacidosis are not the same things. When you hear someone say that ketosis is dangerous or bad for you, they are usually confusing the two. Ketosis, as explained above is a completely normal and healthy state to be in. Ketoacidosis, however, is when ketosis has become extreme. In this case, there is such an excessive amount of ketones that the PH balance of the blood decreases to dangerous levels. Ketoacidosis typically occurs in those with untreated type 1 diabetes mellitus. That is why it is also referred to as diabetic ketoacidosis. Although ketoacidosis is a serious condition, it is essentially a non-issue for healthy individuals.

ConclusionTired Student

This article was in no way meant to be exhaustive or extensively thorough. Instead, it was meant to give a brief overview of the ketogenic diet and to serve as a groundwork for future discussions on the topics presented here. You now have a good understanding of what the ketogenic diet is and some variations on the standard version of the diet.




An early modern human from Romania with a recent
Neanderthal ancestor

Diabetic Ketoacidosis — Medscape

Diets of modern hunter-gatherers vary substantially in their carbohydrate content depending on ecoenvironments: results from an ethnographic analysis — ScienceDirect

Ketone bodies, potential therapeutic uses. — NCBI

Ketones: Your Brain’s Preferred Fuel Source — Ketogenic

Ketosis vs. Ketoacidosis: What You Should Know — Healthline

Metabolic Pathways: How the Body Uses Energy — Ketogenic Diet Resource

What is Acetone — Perfect Keto





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