Ketosis (what it really is)

Many people are getting into keto. Many more people claim to be experts on the subject. The more I read other peoples work and listen to people talk on various podcasts, the more I realize that people don’t actually understand what ketosis is. Today I am going to go down the rabbit hole of what is actually happening to the body when in ketosis.

In the very simplest of terms, ketosis is the body’s way of preserving your brain and organs from starvation. Primarily the brain.

The body’s number one goal is keeping the brain alive. The brain is hungry. It is the most metabolically active organ in the body and uses about 20% calories or about 500 cals a day. The brain can only run on two things. Glucose and ketones. No matter what it still needs some glucose. It can’t run solely on Ketones. The amount it needs reduces dramatically when in ketosis but it still needs some. The need when not in ketosis is 130g per day roughly. When well keto adapted it goes down to about 40g and the rest can be provided by ketones. So why ketones and why ketosis?

When a person is starving, eating less than the body needs to keep up basic metabolic activity, the first priority is always fuel the brain. So what if you are eating a 500 calorie diet? I will say that this happens. Doctors actually put people on this diet along with HCG (a hormone released during early pregnancy that is said to reduce hunger and increase progesterone and estrogen levels). It is dangerous and immoral even according to the FDA who in and of themselves are not great in the morals department. I digress. A person that is on a 500 calorie a day diet has no way of getting enough glucose to feed the brain. Realistically even a person eating 1,000 cals a day is not getting enough glucose to feed the brain considering the standard diet is about 45% carbs. That is only 450 cals of the required 500 cals and not all of those carbs are going to be glucose. So what happens when we can’t feed the brain enough glucose?

When the brain isn’t getting enough glucose we are going to get an emergency call. The responder to this call is cortisol. Cortisol puts out a signal to his buddy glucagon. Glucagon’s job is to get glucose and get it fast. First it reaches out to the glycogen stores in the liver and muscles. It pulls that out and into the blood stream and to the brain it goes. All good for now. Needs are met. That is only going to last maybe 12 hours. Day 2 comes and the brain needs its food. Same process. Not enough glucose to feed the hungry brain so the call goes out. Cortisol spikes, glucagon goes on the hunt for glucose. This time the liver is dry and so are the muscles. What now? Well the brain is hungry and it needs that glucose so the next stop is protein and fats. The body will make about 20% of the required glucose from fatty acids and the rest has to come from protein. So that means if you have only had say 30g of the 130g required for the brain you will need about 100g to be made from fatty acids and protein. So 20% or 20g will come from fatty acids and 80g will have to come from protein. So that is 500 cals worth of protein and fatty acids and that is just to feed the brain. If you are on a 500 calorie diet, or starving, there is no way you will have this amount of either one. OMG! What now.

When the incoming energy does not meet the minimum requirements to feed the body, let alone the brain, the body will do a couple of things.

1. It will start pulling fat from fat stores, this is great cause you will get skinny right?
2. It will start breaking down body protein to use for gluconeogenesis (the creation of new glucose). This is not great. This means lean mass loss.

This is what happens when the above two things start occurring. This is where ketosis comes in. I promise. 🙂

When the body starts using fat for fuel it assumes starvation (or just a state of inadequate fuel). This is the only time in the bodies “mind” that fat would be used. In times of inadequate food to fuel it. This Breakdown of fats for fuel must mean that there is inadequate glucose to meet the needs of the brain. A few other things point to this lack of brain fuel as well such as low insulin and low blood glucose levels. Both of which would be occurring in the current situation. In this perfect storm the body starts making ketones to ensure that the brain gets enough fuel. This is great because now the need for glucose will decrease since about 70% of the brains need for energy can be met by ketones. Number one priority is keeping the brain alive. Second priority is to save organs and lean mass from being eaten to provide fuel for the brain.

Now the protein breakdown part. What if you didn’t create ketones? There are some people that actually don’t. They have a genetic mutation that keeps them from creating adequate ketones. These people are very rare but they would feel absolutely terrible on a ketogenic diet. I can’t seem to find the specific gene mutation but I heard about it on a podcast with Dr. Rhonda Patrick. I digress again. If you couldn’t create ketones to fill some of the need for glucose then the body would have no choice but to breakdown lean tissue (muscle) to make it. Yes you would be losing lots of fat but you would also be breaking down body protein at a fairly high rate. About 80g a day. Before long you would have very little muscle tissue left. At this point the body starts taking organ tissue. This leads to organ failure which is how people die from starvation. Keep in mind, this would happen to everyone eating less than 1,000 cals a day but would take varying amount of time depending on how much bodyfat you have. Once you get below 4% bodyfat the body protein loss amplifies.

Now since we do make ketones, the rate at which this happens greatly reduces. Since the brain’s need for glucose drops to about 40g when in ketosis that means that the amount of protein broken down to provide glucose is greatly diminished and this is how the body protects itself from eating all of it’s lean tissue. In this starvation state, you go from running on primarily carbs to running on primarily fat. Body fat to be precise.

I know I said I was getting to the point. I am, it is just a long point. I’m getting there.

To summarize what I’ve said so far, when inadequate glucose is present to fuel the brain the body will breakdown fat for fuel which will contribute some glycerol to making glucose as well as creating ketones to fuel the brain and take the slack off of protein consumption to create glucose. Essentially the fat being used for fuel signals ketosis.

Now lets look at the ketogenic diet and see how this relates. This will be shorter. I promise.

– When you eat a ketogenic diet you are not eating enough glucose to fuel the brain. This means glucose has to be made from fatty acids and protein since the first priority is keeping the brain alive.
– This would be fine but the body’s second priority is sparing lean mass and organs.
– To keep the lean mass from being catabolized to much the body will start burning fat and making ketones so the need for gluconeogenesis is reduced and we don’t use as much lean mass.
– The other thing that happens is you eat very high fat and your body starts running on primarily fat rather than primarily carbs. Body fat and fat on your plate.

What does all of this have to do with anything? Here it is. The body cannot differentiate between running on primarily fat from inadequate calories to running on fat due to eating primarily fat. Same deal to the body.

The ketogenic diet looks the same to the body as starvation. It meets all the same criteria.

1. Not enough glucose to fuel the brain
2. Low blood sugar
3. Low insulin
4. Gluconeogenesis
5. Transition from carb fuelled metabolism to a fat fuelled metabolism.
6. Ketogenesis

So all the ketogenic diet does is trick the body into thinking it is in starvation to create an environment of fat burning rather than carb burning to spare the body from being catabolized. The big difference is, if you do it right and don’t actually starve yourself, you don’t tank your metabolism and you don’t have to starve.

There you have it. Ketosis is a hack we do to the body to trick it into thinking it is starving. I hope that makes sense. If you have questions feel free to post them to the comments. I know it got a bit long and complicated. Below are some links to further illustrate my point.

Stages of Starvation

Ketogenic Diet mimics starvation/anxiolytic state associated with Anorexia Nervosa

Keto ON!

Coach Jack

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4 Replies to “Ketosis (what it really is)”

  1. Hi Jack , I have a basic beginners question…. when we are in ketosis, does it burn body fat first or dietary fat? If we are eating high fat how does it tap into our body fat for fuel? Thank you!

    1. The body burns both simultaneously. When in ketosis the body is in a state of low insulin/high glucagon. In this state the fat cells are open and fat flows out regardless of current need. The body will take up whatever fat is in the system and ready to be absorbed for energy first. That will sometimes be dietary fat and sometimes body fat. It all sort of finds it’s way into a pool and it is a first come first serve system. Whatever fat is leftover after the bodies energy needs are met, will get converted to ketones. That is why some people will have very high ketones. Their energy needs are low and their dietary fat plus body fat released vastly exceeds the needs of the body so there is alot of leftover to go to Ketones.

  2. Very nice article thank you for explaining it. I am hoping this WOL will help to repair damage done by my MS.
    I love Common Sense Keto!

    1. It is hard to say if it will repair the damage but there is a very good likelyhood that it will slow the damage down. Best of luck on your journey and thanks for reading.

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