Don’t understand ketones,


Please forgive my ignorance & confusion. I’ve been trying to get an answer to this for a while but,… My “Google-Fu” SUCKS. :smiley:

I can’t seem to find a definitive answer to what exactly is the function of the Ketones Im testing for?.

I am having a little trouble reconciling the amount of key tones being excreted in the urine with my day’s dietary intake. Some days when it seem like I’ve taken in a higher number of carbs, I test really high for key tones also. Other days,… even tho my carbs are real low, sometimes I can barely see any key tones in my urine.

Are the ketones in my system/blood/urine? Are these actually the FUEL my body uses/burns after converting fat for energy? OR,… are they the byproducts of having already metabolized fat for energy?

In other words does having a lot of them in my blood just mean I’m excreting extra keytones that I’m not metabolizing? Or does it mean I’ve metabolized a lot of fat therefore I am excreting a lot of key tones?

I have the urine test strips and this occasional apparent discrepancy between my arb intake and the amount of keytones I test postfor has always left me a little befuddled.


(Robin) #2

Welcome to the forum.
You’ll get some good info from others soon enough.
I’ve never seen the point of measuring. I just assume if I’m eating under 20g carbs, I’m good.
That approach has been working for 3 years and 75+pounds ago.

BUT… You are in good company. Many folks here put great stock into ketones and measuring them.
Thanks for joining us. You got this!


I never measured ketones and I am not a very knowledgeable one about them either (I have read about keto bodies and their importance but retaining and even being an educator myself, nope, not that much)… But we do use ketones so if you have little in your urine, it doesn’t mean anything about your ketosis, you may be just more effective at making the right amount and not a ton more like in the beginning. No idea about blood ketones but maybe the same…?
I track my intake, I get feedback from my body so I personally couldn’t care less about the actual levels. Well I don’t need “deep ketosis” if that exists, I am a quite healthy individual who even can even handle some (even a lot) carbs now and then. It is more important for therapeutic keto.

(Alec) #4

My understanding of all this is:

  1. Ketones are a by-product of fat burning in the liver.
  2. Importantly, the goal of the ketogenic diet is not to create ketones, hence a lot of people here (including me) will tell you they don’t bother measuring ketones.
  3. The basics of the ketogenic diet is to eat less than 20g of carbs in a day, the rest of your food should be protein and fat. If you are doing that, it is almost inevitable your body will make ketones, and you really don’t need to measure them.
  4. The point of the keto diet is to use fat as your primary fuel source. But ketones are also used for fuel as and when they are made by the liver.
  5. Therefore don’t focus on ketones… simply focus on minimising carbs to below 20g per day.

(Pete A) #6

The basics of the ketogenic diet is to eat less than 20g of carbs in a day, the rest of your food should be protein and fat. If you are doing that, it is almost inevitable your body will make ketones, and you really don’t need to measure them.


(Chuck) #7

It is not necessary that everyone has to be at or below 20 carbs. I stayed in the ketogenic range with 50 carbs, it just depends on the individual.

(Bacon is a many-splendoured thing) #8

Welcome to the forums!

A ketone is a specific type of chemical recognised by a carbonyl group (with a double bond between a carbon and an oxygen) in the middle. Our logo is the chemical picture of a carbonyl group. The molecular groups attached to the two carbon atoms at the bottom (the “legs” of the logo) determine the type of ketone it is.

The human body produces three chemicals when in ketosis. Two of them, acteone and acetoacetate, are actual chemical ketones. The third is called β-hydroxybutyrate, and it’s not actually a ketone, but it’s produced by the same processes. So you will often hear or read the phrase “ketone bodies” in recognition of that fact. But people sometimes just call all three chemicals “ketones” for the sake of simplicity.

What is a ketone body? It is made during the process of metabolising a fatty acid. My favourite metaphor is that a ketone is to a fatty acid as charcoal is to wood. They are both partially metabolised/burnt versions of the original item (fat/wood). Most cells, when they metabolise a fatty acid, continue all the way to the end products of CO2 and H2O. However, when we are in ketosis, the liver makes ketone bodies to fuel cells that can use them.

Ketone bodies have many uses throughout the body. They can serve as alternative fuels to glucose or fatty acids, and β-hydroxybutyrate has a role in healing damaged intestinal walls, because it helps restore the tight junctions that are loosened when someone has leaky gut syndrome. The three ketone bodies also have powerful hormone-like effects throughout the body. Acetone has an important role in brain function, and β-hydroxybutyrate, among other things, affects the genes that control our endogenous (built-in) defences against oxidative stress.

We measure ketones primarily as a way of gauging the effect of our low-carbohydrate, high-fat, ketogenic diet. The point of the diet is actually to lower serum insulin levels below a certain threshold by restricting carbohydrate intake, and we know that insulin is low enough when the liver starts producing detectable amounts of ketone bodies. We cannot measure insulin at home, but there are simple home tests for the three ketone bodies. The ketones circulate throughout the blood stream, and they are excreted in breath and urine.

It is easiest to measure acetone in the breath, acetoacetate in the urine, and β-hydroxybutyrate in the blood, but all three ketone bodies are found in all three locations. The definition of nutritional ketosis is a blood level of β-hydroxybutyrate of 0.5 mmol/dL or higher. Fasting levels of ketones tend to be higher, starting around 4.0 mmol/dL and going up to around 7 or 8. Doctors start worrying about diabetic ketoacidosis when β-hydroxybutyrate reaches 10.0 mmol/dL, but symptoms don’t manifest until around 20.0.

When we first embark on a low-carbohydrate ketogenic diet, the liver produces ketones in abundance. The skeletal muscles have to go through a period of adaptation, in which they are busy reactivating certain metabolic pathways and in healing the mitochondria that were damaged by too much glucose (carbohydrate). Skeletal muscles prefer fatty acids, but until they readapt to metabolising them, they have to limp along on ketone bodies. That is why ketones are so easily detectable at the beginning.

As the muscles become fat-adapted or keto-adapted, as we call it, the liver starts matching ketone production more closely to demand, and people often (though not always) see a drop in excreted ketone levels. Even serum β-hydroxybutyrate tends to drop a little, as once the muscles are metabolising fats, there is not such a great need. Some organs prefer ketones, particularly the brain, since fatty acids cannot cross the blood-brain barrier. If ketones are available, the brain will use them in preference to glucose. Some cells, however, require glucose. The big example is our red blood corpuscles; they lack mitochondria, so they cannot metabolise fats or ketone bodies.

All right, that seems like a long enough biology lecture for now. I hope it helped. If I missed something, or you have any further questions, feel free to post them.


My Apologies!! LoL! It would appear I got my answer while writing the following rant!
So,… in the immortal words of Emily Lotela,
“Never Mind!” :rofl::man_shrugging::man_facepalming:

So I’m looking for ways to word this so that I don’t unnecessarily upset the community or come off as some sort of angry, entitled noob,…

I do appreciate the advice and thinking on why it is I shouldn’t necessarily bother to test for ketones. But that wasn’t really what I was asking about. Im here looking for some information not necessarily instruction on the lifestyle.

Whenever I try to Google anything about keto, ketones or ketosis,… I either get a LOT of information on diabetes, or I get RECIPES. :man_shrugging:

I never seem to find any information on what exactly ketones are and how/why they’re being produced in my system when I reduce my carbs.

For me,… right now,… keto is a TOOL im using for weight loss. Nothing else. Its Not necessarily going to be a lifestyle choice . And as a tool for weight loss,… I am trying to understand and optimize what’s going on and why I test as having the amount of key tones that I do.

And again, NOT meaning to insult, impugn, or malign anybody,… I seem to have gotten some conflicting information again.

@Alecmcq replied first that key tones are a BYPRODUCT of fat metabolism. And then said in the same reply, that ketones are produced by the liver to be USED as fuel. Now I think I understand how that can BOTH be true. If that’s actually what’s going on, If so, I presume it’s possible because FIRST, fat needs to be converted by the liver into ketones in order for me make use of The fat as an energy source,…? But Im only guessing.

Im neither a doctor or a nutritionist so I’m not exactly sure how fat is used & metabolized once the body starts using it instead of carbs.

Once again, if I could just get some information,…

“Are the ketones themselves what I’m ACTUALLY metabolizing/ burning for energy AFTER having acquired/converted them from FAT?

OR,… are the ketones present as a metabolic Waste product because Ive already converted fat to usable energy and ketones are what’s left to excrete?

I appreciate your patience with me, and any insight you can give me into my inquiry. Thank you :sunglasses::+1:t2:

(Bacon is a many-splendoured thing) #10

I hope my earlier post helped answer that question. The body has basically two metabolic states, determined by the serum insulin level.

The most common state, given our current governmental dietary advice, is a state of metabolising glucose and storing fat. Insulin levels are high because of the excessive carbohydrate intake, and we store fat because of the high insulin level. This mechanism is very similar to how a bear puts on fat by eating berries in the autumn, so that it has fat to live off while hibernating during the winter.

The other state, which some people argue is really our natural state, is a state of metabolising fatty acids and ketone bodies. The low insulin level signals to the liver to make the small amount of glucose that the body actually needs (gluconeogenesis) and to make ketone bodies (ketogenesis). The value of ketone bodies was described in my earlier post.

A high glucose level in the blood is damaging, and can be fatal, which is one of the reasons a high carbohydrate (glucose) intake elicits a pronounced insulin response. This response puts the body into glucose-metabolising mode and drives the glucose that the skeletal muscles can’t handle into the adipose tissue for storage. As the fat cells get overwhelmed, they start resisting the insulin signal, so the pancreas has to secrete more and more insulin in order to deal with the glucose load.

Hyperinsulinaemia is just as damaging to the body as hyperglycaemia, so the benefits of eating in a way that keeps serum glucose and insulin low are obvious. However, this advice runs counter to the entrenched dietary guidance that has been handed down since 1980, so the ketogenic diet is quite controversial. However, insulin-resistance has been implicated in gout, Type II diabetes, Alzheimer’s disease (often called Type III diabetes), obesity, hypertension, cardiovascular disease, many (if not all) cancers, systemic inflammation, most mental problems and motor-neuron diseases, and so forth.

The point of a ketogenic diet is the restoration of metabolic health. The chronic diseases that plague people on the standard Western diet are all manifestations of hyperinsulinaemia/insulin-resistance, and lowering serum insulin can relieve those conditions. The ability to mobilise fatty acids from our adipose tissues is a delightful side effect. Many people come to us seeking to use keto for fat loss, and end up delighted with the improvement in their health.

Most people find it more helpful to think of a ketogenic diet as a permanent change in their way of eating, than as a quick weight-loss fix. For one thing, the keto-adaptation process I mentioned takes generally four to six weeks, in most people. The real benefits of a ketogenic diet often don’t manifest themselves till that point. For another, a low-carb ketogenic diet turns the standard dietary advice upside down, and that often requires a psychological adjustment.

And don’t obsess over your ketone levels. Measuring them is primarily for the sake of knowing that insulin has dropped low enough to put us in fat-metabolising mode. Without carbohydrates in the diet, our body turns to metabolising fatty acids, both from our diet and from our bodily fat stores. The presence of ketones is an indication that we are in that state, and the absolute measured value is not particularly indicative of the speed of fat loss.

It is a kind of joke to say this, but it is also true. The easiest test to see if you are in ketosis is to ask two questions:

  1. Are you eating less than 20 g/day of carbohydrate?
  2. Are you breathing in and out?

If you can answer Yes to both questions, you are in ketsosis.

(KM) #11

Yay Paul!!! :heart:

“What are ketones”?

Um … er … well … I … ah yes, this Is the ketogenic forum, but … mmm … ask Paul. It’s sort of embarrassing. (For me, I mean, I’ve been here on and off for five years and I couldn’t comfortably answer that with any degree of self assurance). Nevertheless, thank goodness for Paul!

The one unscientific thing I’ll add is that 20g of carb is not carved in stone. 20g total carbs is little enough to put nearly anyone into ketosis, which happens when there is very little dietary glucose intake, and the glycogen stored in liver and muscles is depleted - which usually happens within about three days. Some people don’t have to go that low, and a few people need to drop it even lower.

Edit: I do use pee sticks at times. I will show at least a trace of pink if I’m in ketosis (some people apparently don’t), and they help me determine my Upper limit of carbs. (They really don’t tell me anything about my state of ketosis other than it exists.) If I were less of a wimp I’d get a blood ketone meter, but peeing on a stick is about as close to falling on a sword as I’m going. :rofl:


@PaulL Thank you for the informative and detailed reply.

I’m definitely eating more than 20 g of carbs probably closer to the range of 30–35g. occasionally as high as 40g. In the past thosr numbers seem to work for me. I have been on the Keto diet off & on over the last 3-4 years since being diagnosed with AFIB.
(…Cardiologist required me to lose some weight,)

Oddly enough, although all my cholesterol numbers are within normal, acceptable limits. The various cholesterol components tend to switch places on KETO compared to what they are when I’m on a regular carbohydrate-based diet. My overall cholesterol remains well below 200 but My HDL goes down, LDL goes up, triglycerides go up. etc. But none of them rise to the range of being of concern.

I appreciate your taking the time to reply thank you

(Bacon is a many-splendoured thing) #13

That can certainly work, so long as you are fairly insulin-sensitive. As @kib1 points out, the 20 g/day recommendation is somewhat arbitrary. Carl and Richard set it as a level that guarantees success for everyone but the most insulin-resistant people.

Dr. Eric Westman at Duke University recommends a total of 20 g/day as well, but Dr. Stephen Phinney, who coined the term “nutritional ketosis,” recommends a 50 g/day total limit, in the hopes, as he says, that net (digestible) carbs will be under 20 g/day.

When you eat a well-formulated low-carb, high-fat, ketogenic diet, your triglyceride number should go down (because of the low carbohydrate intake), and your HDL should go up (because of the greater fat intake, especially saturated fats). The ratio of triglycerides to HDL should be under 0.9 (in most of the world) or under 2.0 (in U.S. units). LDL numbers are completely irrelevant.


Indeed, we need to be below our individual ketosis carb limit, be it 10, 20, 40 or 80g net or total carbs a day. For example, I have found that mine is about 45g net and unlimited total. It probably changes, it should if my activity drastically changes but never noticed it and I never am highly active anyway…
That’s for ketosis.
I don’t know if measuring more of some ketone bodies is good or not (I remember we want the effective β-hydroxybutyrate and pee sticks are pretty useless after a while when our body stops pumping out the one it measures like no tomorrow… blood works best I think, with the mentioned one if I remember well. I am sleepy now and postponed reading what Paul wrote but I will. one day I will memorize the stuff…) but ketosis isn’t enough for many of us. And not needed for others. I just ask my body if it feels good on my actual woe (well no, it screams its more serious problems, no asking is needed) as that matters most, not some numbers that I either can get somewhat accurately or not. But I understand wanting numbers, I track every day so I am into numbers too just different ones.

(Bob M) #15

If you’re eating a low carb/keto diet, HDL should go up, triglycerides should come down, relative to a higher carb diet. LDL may or may not change.

(Robin) #16

I think you’ll find that keto is a great way to lose weight.
Your next challenge will be keeping the weight off, but you already know that. Best of luck!
You got this!

(Harriet) #17

I have a breath ketone meter (well, it measures acetone). Since it’s right there and easy to use I have tested my breath many times throughout the day. My personal observation is that my body takes about 24 hours to reflect what I have or haven’t been eating. If I fasted on Monday, for example, my acetone stays very high most of Tuesday.

(Bacon is a many-splendoured thing) #18

Acetone is the ketone easiest to measure in breath. Acetoacetate is what the urine strips measure, and blood meters measure β-hydroxybutyrate. Though it’s probably worth bearing in mind that all three ketone bodies can be found in all three locations.


No, it’s not. That’s just a safe spot for almost everybody, but way too many think that’s some magical requirement, everybodys metabolism is different.