Don’t Fall Victim To Ketone Envy.

Ever wanted to know what it means to have more or less ketones, and how should we measure them?


A common misconception of ketones, since they are produced from fat, is that more ketones = more fat burning.

This sadly is not the case.

Let’s explore some entry level biochemistry.

So the image below  is about the most simple one that I like and we can use for our purposes. With carb reduction, fats first enter lipolysis (about 50-150g of carbs/day). Yes, someone can maintain this level of carb reduction and not be in ketosis yes still use free fatty acids (FFAs) for a lot of their energy. However, their brain is still getting it’s energy from glucose, as the brain cannot utilize FFAs. Upon reducing carbs low enough that GNG from protein and fats cannot keep up to provide the brain with energy the body decides ketones would be a better option to fit the bill.


Ketone Diagram
The Ketone Diagram


Blood Ketones

So, now that we are in ketosis, our liver is producing all these ketones. Where do they go? They circulate in the blood. Blood ketone testing is considered the most accurate way of testing ketosis levels because this is the “fuel tank” for ketone usage. I’ll come back to why this still is an inaccurate way of measuring ketone “use” or keto-adaptation.

Blood Ketone Meter
Blood Ketone Meter


Urine Ketones

Urine ketones are considered the most common way but tell you literally nothing about how many ketones you used. The equivalent is looking at how many carbon deposits an engine has trying and to figure out the gas mileage; all you are seeing is the residual byproduct that varies from situation to situation based on many factors. Urine ketones only show the excess and unused ketones that were circulating. Also, as you see in the picture above, only acetone is excreted through urine.


Urine Ketone
“Pee” Stix


Thanks to /u/fury420 from Reddit, it has been brought to my attention that acetone is the primary ketone found in urine, but there typically are trace levels of ACA as well.
Ketostix use a reagent known as nitroprusside, which reacts strongly to acetoacetate and weakly to acetone.

If you can leave this thread with one piece of knowledge it’s to stop using ketostix.

They are not for people in nutritional ketosis. They are for diabietic to ensure they aren’t going to go into diabetic ketoacidosis, which isn’t a problem for those with normal insulin function. The only thing you’ll do by using ketostix is freak yourself out wondering if that normal or if you did something wrong. Also, at worst case scenario, you could’ve done something wrong (eaten too many carbs) and caused ketones to stop being used because your body is trying to metabolize the glucose first so it flushes the ketones out of your urine and you think “whew, I’m still in ketosis” when in reality *you are only seeing ketones because you are not in ketosis.* See why they are misleading? There are many other backwards cases and I’m not going to go into them. Just don’t use the stix. Thank you.

Breath Ketones

Breath acetone is a reliable indicator of ketosis, specifically because it directly correlates with blood BHB. In other words, acetone is a byproduct of BHB and is excreted through breath. The sad part is in some cases, excess acetone itself can be excreted through the breath.

Ketonix Breath Analizer
Ketonix Breath Analizer

So to look at this whole formula it goes like this:

Liver produces ketones to circulate as blood ketones ->

You body uses what it needs and produces a byproduct in some cases (BHB) that is excreted through breath ->

Those that are not used are excreted through urine.

Back to blood ketones

If we take our car analogy, most people want to know the mileage of their car. Trying to find the mileage of our ketone use is basically impossible, because all we can see is the gas tank.

Look at it this way: energy burned is our engine, the exhaust is our breath (some waste, some natural byproduct) urine is the carbon deposits (waste of sorts), blood ketones are the fuel tank. Let’s hypothetically say our car is running 24/7, and by some mechanism there is a way that gas is automatically being refilled. When we read our fuel tank and it says 1/2 tank, that’s like seeing our ketones at 1 m/mol.

All it means is there are still ketones available. We don’t know how much is going out because we don’t know much is coming in either. We can try and gather all the exhaust, waste, and try and subtract the difference between any changes in our “gas tank,” but that would still be somewhat inaccurate because there would be too many factors to consider how much energy is actually being used.

So what does that mean for measuring ketones? Don’t worry about it.

Your body naturally tries to find an equilibrium that is necessary to run efficiently. It doesn’t want to overproduce ketones and waste energy. So often you can see endurance runners that have been in ketosis for years that run miles each day have only .1 m/mol in their blood. That is because their body is using all of their ketones at a nearly equal rate that it is producing them. It doesn’t mean that their body isn’t using ketones, quite the contrary, they are constantly doing aerobic exercise so their body is constantly using the ketones.

You’ll also see people starting keto have higher amounts because their body is trying to produce more to give them energy, but their mitochondria are not yet adapted to using ketones, so there is some produced in excess.

Don’t bother with measuring ketones. There are very few reasons to measure them once you understand that carb reduction causes ketone production and use. A few examples I can think of is to find out how certain carb foods affect you, and I can see measuring ketone levels being useful if you’re incorporating exercise and trying to figure out where your limit of ketone use vs glycogen use lies. In fact, the more that you look at and measure specific exercise issues, the more measuring ketones becomes a necessity, as per the work of Volek and Phinney in particular.

Thanks for reading. I hope that everyone who is worried about their ketone levels can now keep calm and keto on.

It seems a few people are curious what we *should* be looking at for measuring ketones. IMO a cheap breathalyzer off eBay or Amazon (~$10 USD) should measure you pretty closely to what you need to know. I’ve been able to land in between .02-.05 consistently. Myself and a few other Ketogainers are working on comparing breath readings with blood readings. Hopefully we find consistency and then everyone can have a cheap, renewable way of measuring ketones that nobody can complain about being inaccurate.


Originally posted to reddit, copied because I am the author (/u/naonin)

Here’s the link if you’re interested in the discussion:

Edited by /u/darthluiggi