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Ketosis, Ketones, and How It All Works

Ketosis, Ketones, and How It All Works


Ketosis is a process that the body does on an everyday basis, regardless of the number of carbs you eat. Your body can adapt very well, processing different types of nutrients into the fuels that it needs. Proteins, fats, and carbs can all be processed for use. Eating a low carb, high fat diet just ramps up this process, which is a normal and safe chemical reaction.

If you’d like to visit one of my favorite sites on ketosis and the science behind it – check out http://www.ketogenic-diet-resource.com/

When you eat carbohydrate based foods or excess amounts of protein, your body will break this down into sugar – known as glucose. Why? Glucose is needed in the creation of ATP (an energy molecule), which is a fuel that is needed for the daily activities and maintenance inside our bodies.

If you’ve ever used a calculator to determine your caloric needs, you will see that your body uses up quite a lot of calories. It’s true, our bodies use up much of the nutrients we intake just to maintain itself on a daily basis. With glucose, if you eat enough food, there will likely be enough excess that your body doesn’t need.

There are two main things that happen to glucose if your body doesn’t need it:

  • Glycogenesis. Excess glucose will be converted to glycogen, and stored in your liver and muscles. Estimates show that only about half of your daily energy can be stored as glycogen.
  • Lipogenesis. If there’s already enough glycogen in your muscles and liver, any extra glucose will be converted into fats and stored.

So, what happens to you once your body has no more glucose or glycogen? Ketosis happens.

When your body has no access to food, like when you are sleeping or when you are on a ketogenic diet, the body will burn fat and create molecules called ketones. We can thank our body’s ability to switch metabolic pathways for that.

These ketones are created when the body breaks down fats, creating fatty acids, and burned off in the liver in a process called beta-oxidation. The end result of this process is the creation of ketones, which are used as fuel by the muscles and brain.

Efficient Brain on Ketones
Although glucose is the main source of fuel for most people, these fatty acids are used by the brain cells when carbohydrate or food intake is low. In simpler terms, since you have no more glucose or glycogen, ketosis kicks in and your body will use your stored/consumed fat as energy.

Ketosis is pretty amazing, and in fact, gets even better. Studies show that the body and brain actually prefer using ketones, being able to run 70% more efficiently than glucose. From an evolutionary standpoint, this makes perfect sense.

Our ancestors didn’t always have access to food, and they certainly didn’t always have access to glucose. Their body was feasting on the fat from the last woolly mammoth or saber-toothed tiger.

So, How Does Ketosis Work?

When fat is broken down by the liver, glycerol and fatty acid molecules are released. The fatty acid is broken down further, in a process called ketogenesis, and a ketone body called acetoacetate is produced.

Acetoacetate is then converted into 2 other types of ketone bodies:

  • Beta-hydroxybutyrate (BHB) – After being keto-adapted for a while, your muscles will convert the acetoacetate into BHB as it’s preferred by the brain as fuel.
  • Acetone – Can sometimes be metabolized into glucose, but is mostly excreted as waste. This gives the distinct smelly breath that most ketogenic dieters know.

Over time, your body will expel less ketone bodies, and you may think that ketosis is slowing down. That’s not the case, as your brain is burning the BHB as fuel, and your body is trying to give your brain as much efficient energy as possible.

This is commonly why long-time low carbohydrate consumers will not show deep levels of ketosis on their Ketostix.


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Spectrum Expeller Pressed Organic Coconut Oil
Sunbeam 76893.05 Kitchen Bake 5-Piece Bakeware Set

The glycerol that was created will be converted into glucose in a process called gluconeogenesis. This is a normal metabolic process that creates glucose from the amino acids in protein, lactate from the muscles, and the glycerol from fatty acids.

Glucose is needed by the body, in small amounts, to maintain good health – but carbohydrates aren’t needed. Your liver will always make sure you have enough glucose in your bloodstream for the body to perform healthily, no matter what.

In fact, about 56% of excess protein will be turned into glucose in your blood stream – this is why too much protein is a bad thing and can knock you out of ketosis. Don’t worry – as long as you are following your macros, this will not be a problem for you.

woman starvation
As long as you are eating enough protein and fats each day, the liver can perform gluconeogenesis from the amino acids and fatty acids you ingest. This is important, because if you are not eating enough protein, your muscle tissues will be burned to make the glucose that your body needs.

It’s important to note that ketosis and starvation is two different things. Starvation happens when you have no food sources. Your body will start to convert the protein in your muscles to glucose, causing muscle loss.

Yes, you lose weight in starvation; your body also converts the fat in your stores to glucose in order to survive. But this is not healthy. Do you want to look like a ragdoll of skin and bones? Didn’t think so.

In normal states, we have fat stores to be used, and the ketogenic process will help us preserve our muscle tissue by using ketosis and the ketone bodies we create for fuel.

Special thanks to Daerina at Reddit, for designing this awesome infographic for us!

Ketosis Infographic

As always, I appreciate any shares that you give to your social networks! Let me know your thoughts on ketosis in the comments below :)

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  1. So I take it glucose produced via gluconeogenesis doesn’t generate an insulin response?

    • Ryan, it does create an insulin response but not a large one. The glucose that is formed during gluconeogenesis is normally used to keep our glucose at a necessary baseline. If you’re overconsuming on protein, the excess glucose can cause an increased insulin response, though.

  2. Great breakdown of ketosis. I liked the point about not detecting urine ketones after awhile of being in ketosis. Any data on blood ketones dropping after awhile? Many of us use blood meters now, which detect blood ketones (and is a lot more accurate).

    • Thanks a lot!

      Your blood ketones don’t usually drop too much unless you’re starting to bring up your other macros like protein and carbs. Although, after a while, your body will be using your ketones more effectively than when it isn’t deeply keto-adapted. Hope that answers your question – I try to keep it relatively simple for people just starting out.

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