What is the Keto Diet?

The Keto Diet – What Is KETOSIS?

The keto diet is by far one of the most controversial and fascinating diets I have yet to research. While it has been utilized within the medical community for decades, it has recently hit mainstream as a weight loss method.

I have questions, such as why would people want to emulate starvation to lose weight? Is this diet sustainable? Most importantly, is it a “lifestyle diet” like some people are claiming it to be? I am in search of knowledge and a deeper understanding.

Before You Read Further:  please know that I am not, nor have I ever claimed to be, a doctor or scientist. I have never worked on a case study that examines ketogenic diets or ketone supplements. Within the keto diet blog series, I make no claim that the statements are 100% accurate and true. My goal is not to tell anyone if this diet is right or wrong for them. My goal is provide a reliable non-biased source of information backed by scientific-based research.

So, let’s now learn what the keto buzz is all about!


The ketogenic diet is not new. In fact, keto diets have been used by the medical community since the 1920s to help treat epilepsy. Since the 1960s, they have been used to treat clinical obesity. There is emerging evidence that the keto diet may also help with diabetes, polycystic ovary syndrome, acne, neurological diseases, select cancers, pain and inflammation, the amelioration of respiratory and cardiovascular disease. (1) Check out The Charlie Foundation for Ketogenic Therapies to learn more about how the ketogenic diet is being used to help treat certain illnesses.

Today, we see the keto diet hitting mainstream mainly for weight loss, and not under the care of a practitioner.  Some people are practicing a nutritional ketogenic diet, using only real food. Others use a combination of a nutritional keto diet and exogenous ketone supplements.

Ketone supplements are supposed to help elevate ketone bodies in the blood so one can get into ketosis quicker. With keto diets becoming so popular, and people always wanting quick results, the demand for ketone supplements has increased. We are seeing brands popping up everywhere. I will speak more on exogenous ketone supplements in another subsection of this blog series.


Before we look further at the keto diet, we must understand what it is to be in the state of ketosis.

  1. Glucose is your body’s primary fuel source.
  2. Glucose is formed within the body from eating carbohydrates, such as fruit, veggies, berries, leafy greens, milk sugars, wheat, grains, candy, pop, etc.
  3. To reach ketosis, you must greatly reduce glucose levels by limiting carbohydrates in your diet to about 5% of your total daily calories.
  4. You also must consume a diet high in fat, generally 70-85% of your total daily calories.
  5. Protein intake must be limited to about 10-25% of your total daily calories.
  6. This diet needs to be maintained every day to reach ketosis.
  7. Once your body is depleted of glucose, it will search for a new energy source so it can function and stay alive.
  8. The body will metabolize fat to generate a new source of energy.
  9. Through the metabolism of fat, higher levels of ketone bodies are produced in the blood.
  10. These ketone bodies are then utilized by the body as the primary energy source.
  11. This process is called ketogenesis, which is the necessary process required to bring you to the metabolic state of ketosis. (2)

Simply put, ketosis is a normal metabolic state where the body utilizes fat, in the form of ketones, as its primary fuel source instead of glucose.


Now, it’s not so simple for everyone, not that the keto diet is simple by any means. Imagine eating only 5% of your total daily calories from carbohydrates. To put this in perspective, on a 1500 calorie ketogenic diet for weight loss, your daily macro-nutrient profile could look like this:

  • Fat:  75% of total calories; 125 grams; 1125 calories
  • Protein:  20% of total calories, 75 grams; 300 calories
  • Carbohydrates:  5% of total calories; 19 grams; 75 calories

Keep in mind that this calculation above is just one of many variations. While the standard ketogenic diet ratio is 4:1 (4 grams of fat to 1 gram of protein and carbs combined), this is not set in stone. We know that every ‘body’ is different. Some people need to eat lower amounts of protein and higher amounts of fat. Also, some people may only need a few days to enter into ketosis where others may take several weeks. There are many individual factors to take into consideration, such as your current metabolic state.

Also, if you aren’t tracking your calories and macronutrients, then you won’t know for sure if you are in ketosis. People can eat a low carb diet and still NOT be in ketosis.  You will need a device to measure your ketone levels in your blood, breath, or urine. There are several gadgets on the market that can help you do this.


An interesting fact to know is that the central nervous system, the brain and spinal cord, can not directly use fat as an energy source. It prefers glucose. When it sees that there is no glucose available to utilize, it goes through the ketogenesis process described above, which generates the ketone bodies. When the ketone bodies reach a certain concentration, they are then utilized by the central nervous system as an energy source. This is how our brain can use “fat” as fuel. (3)

Think about the cave men, hunters and gatherers, people who have very little food, or people lost or stranded without food. During times of starvation, or prolonged periods of no carbohydrate consumption, ketosis allows us to stay alive.


One can stay in ketosis for as long as they like, given they can maintain the low carb high fat ketogenic diet with no severe side effects or health risks.

However, as soon as glucose levels becomes sufficient enough to supply the central nervous system with energy again, you will be “knocked out of ketosis.” Glucose is a quicker and more efficient energy source for the brain and body to use than fat. To stay in ketosis, you have to really watch your carb intake.

Are their benefits and risks of staying in ketosis long-term? For sure, and that will be discussed in a future subsection.


To sum it all up, ketosis is a metabolic state where the body utilizes fat instead of glucose as its primary fuel source. Your body enters this state by eating an extremely low carbohydrate high fat diet. It can take days or weeks to enter into ketosis, depending on the individual. To stay into ketosis, you maintain the diet!

I hope this explanation was simple enough to get a basic understanding. If not, please feel free to ask questions in the comments section below. Also, if you have anything to add, feel free to speak your mind.

Scientific sources:

(1)(2)(3) Paoli, A, et al. “Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets.” National Center for Biotechnology Information. June 26, 2013. Accessed October 14, 2017. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3826507/

Additional sources:

MacIntosh, James. “Ketosis: What is Ketosis.” Medical News Today. March 21, 2017.  https://www.medicalnewstoday.com/articles/180858.php

Dieter, Brad. “The Ketogenic Diet.” Science Driven Nutrition. July 13, 2016. http://sciencedrivennutrition.com/the-ketogenic-diet/

Lindsey Thompson, Lindsey. MS, RD, CSP, LDN. and Turner, Zahava Turner, RD, CSP, LD. “The Classic Ketogenic Diet: Evidence, Diet Calculation and Case Reports.” Nutricia Keto University. July 29, 2015. https://www.nutricialearningcenter.com/globalassets/pdfs/neurology/ckd-july-webinar-final.pdf?epieditmode=False

Fran, Shelly. “The fat-fueled brain: unnatural or advantageous?” Scientific American. October 1, 2013. https://blogs.scientificamerican.com/mind-guest-blog/the-fat-fueled-brain-unnatural-or-advantageous/

DISCLAIMER:  The information in this weblog is provided “AS IS” with no warranties, and confers no rights. This weblog does not represent the thoughts, intentions, plans or strategies of GO FIT LIFE! It is solely my opinion. Feel free to challenge me, disagree with me, or tell me I’m completely nuts in the comments section of each blog entry, but I reserve the right to delete any comment for any reason whatsoever (abusive, profane, rude, or anonymous comments) – so please, keep it polite.
Get a FREE copy of my NEW Walk-Run 5K Ultimate Beginner Training Guide when you sign up for my weekly newsletter. I provide insider weight loss tips, healthy recipes, workouts and special promos only for my subscribers. JOIN HERE!

Related Articles


Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.