Measuring Ketosis With Ketone Strips: Are They Accurate?
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Many people following keto diets want to be in ketosis, a natural state in which the body burns fat for fuel.
For this reason, people are curious about whether they are doing enough (via carb restriction) to achieve this state.
As a result, ketone strips are a popular tool that numerous people use as a way of measuring ketosis.
However, just how accurate are they?
And how do they compare to alternate methods of measuring ketones?
What is Ketosis?
Anyone following a standard high-carbohydrate diet will be burning glucose for energy.
However, the body can use both carbohydrate and fat for fuel (1).
When carbohydrate intake is very low, the body switches to burning fat for energy. As this happens, our body enters a state of ketosis.
Ketosis is a natural biological state during which our body burns fat for fuel. While we are “in ketosis,” our blood levels of ketones—a by-product from the breakdown of fats—rise.
Measuring these ketones (also known as ‘ketone bodies’) can, therefore, provide a hint as to how deeply our body is (or isn’t) in ketosis.
For this reason, ketone strips—which measure the level of ketones—have become increasingly popular in recent times.
What are Ketone Test Strips?
For people who want to know if they’re in ketosis, ketone test strips are a cheap and simple way of detecting ketone levels.
They are otherwise known as ‘ketone sticks’ and work by urinalysis to tell us the volume of acetoacetate in our urine.
If you don’t know what acetoacetate is, then let’s start at the beginning.
First of all, there are three types of ketone body;
- Acetoacetate
Acetoacetate is one of the two main ketone bodies, and it is present in urine.
We can test for it by using ketone strips.
- Beta-hydroxybutyrate
Beta-hydroxybutyrate is created from acetoacetate, and it is the second of the main ketone bodies.
This ketone body shows up in our blood, and blood ketone meters can tell us the volume.
- Acetone
Acetone is also a ketone body, although not as prevalent as acetoacetate and beta-hydroxybutyrate.
The breakdown of acetoacetate produces acetone, and it is present in our breath.
How Do Ketone Strips Work?
You can probably guess the finer details, but if you want to know how to use ketone strips, the process looks like this;
- Take a urine sample in a clean container/jar of some sort
- Hold the end of the strip in the urine for a few seconds
- Shake the strip to remove any excess “liquid” before removing from the container
- Wait 15 seconds until the ketone strip changes color
- Comparing the color of your ketone strip to the color chart will let you know if you’re in ketosis (and how deeply).
Here is a video of someone doing it;
Knowing how to read the ketone strip is important too, so here is the color chart;
The color on the far left means that no ketones are present, and the pink colors signify a light to medium state of nutritional ketosis.
As we move further to the right, the darker purple shades suggest a very strong level of ketosis.
| State of Ketosis | Ketone Level (mmol/L) | Ketone Level (mg/dL) |
| Very light | 0.1 – 0.5 | 1 – 5 |
| Light | 0.6 – 1.5 | 6 – 15 |
| Medium | 1.6 – 3.0 | 16 – 30 |
| Strong | 3.1 + | 31 + |
What Level of Ketone Bodies is Best For Health?
For those aiming to be in ketosis, what kind of reading should we strive for?
I have a feeling that many will look at the table and automatically assume that ‘strong’ is best.
However, for the average person just looking to take care of their health—or maybe lose some weight—higher levels are not necessary at all.
If you’re in the ‘light’ range, then your body will be burning fat for fuel, and you’ll have ketone levels that are many multiples of the average person.
In short, aiming for a random ‘optimal’ ketone number isn’t the right approach.
Listening to your body and seeing how you feel? That’s the right way to go about it.
Note: If you are undertaking a ketogenic diet for a medical purpose, speak to your physician about this. Therapeutic ketosis levels may be very different to what the average person needs.
How Accurately Do Ketone Strips Measure Ketosis?
On the negative side, ketone strips are not always as accurate as most people believe.
For example, here are a few circumstances in which an inaccurate reading could be possible;
Ketones in Urine Don’t Give a True Indication of What’s Happening in the Body
Ketones in Urine Don’t Give a True Indication of What’s Happening in the BodyIn the first place, any ketones which go unused by the body are excreted via urine (2).
To put that differently, urine strips only show the number of excessive ketones that our body couldn’t use.
Therefore, just because the level of ketones in urine is small doesn’t mean that the levels in our blood are also small.
Nor does it mean that we are not in ketosis.
For this reason, blood ketone levels are a more accurate way of measuring ketosis than ketone test strips.
Hydration – Does Over/Under Hydration Affect Ketone Levels?
First of all, this idea relates to how well hydrated (or dehydrated) someone is, and whether this state impacts the ketone strip reading.
For instance, if someone is drinking large amounts of water, then it may dilute urine to the extent that affects the reading.
On the other hand, if someone is dehydrated, then higher concentrations of ketones may be present.
However, I’m not convinced that hydration greatly impacts the reading.
Ketone strips are designed for the average person consuming typical amounts of water. If someone is seriously dehydrated or drinking extreme amounts of water, then yes… this may potentially impact the reading.
But for the average person, I don’t think hydration should significantly affect these readings.
Keto-Adaptation
Keto-AdaptationIt takes time to adapt to burning fat for fuel.
For example, you may have heard about the ‘keto flu.’
This particular name refers to the often uncomfortable period during which the body learns to use fat for fuel rather than glucose.
In other words, when someone first starts a ketogenic diet, the body won’t be using ketones efficiently (3).
As a result, it’s likely there will be a higher concentration of waste ketones in the urine in the initial stages.
Over time and as the body adapts to burning fat for fuel, it should become more adept at burning ketones for energy. As this happens, the volume of ketones we excrete will fall.
Consequently, ketone readings may go down at this time.
This disparity may be confusing since your body will be more in ketosis, yet with a lower level of ketones showing on the ketone strip.
It is a reason why ketone sticks don’t tell the full story and why their accuracy isn’t always reliable.
What Are Some Other Ways To Measure Ketones?
There are three main ways of measuring ketones in the body;
- Blood meters (beta-hydroxybutyrate)
- Breath analyzers (acetone)
- Urine strips (acetoacetate)
As we have already gone through the latter, let’s look at the other two methods.
Ketone Blood Meter
Ketone blood meters are more accurate than testing by urine strips.
However, this extra accuracy comes at a higher price.
How do blood ketone meters work?
- First, you need to insert a blood ketone strip into the ketone meter.
- After this, prick your finger to draw some blood (don’t worry, it’s just a small drop like a standard blood glucose test).
- Put the blood on the ketone strip and check the results.
This technique is simple, and as previously mentioned, levels of ketones in the blood give a more reliable indicator of ketosis than urine levels.
Breath Ketone Analyzer
While ketone breath analyzers don’t offer the same accuracy as blood meters, they have some positive points;
- The initial purchase of the equipment is more expensive than ketone strips, but it’s a one-time deal. No more purchases are necessary. Unlike the other two methods, you can re-use the breathalyzer as much as you want. It’s by far the most cost-effective way of measuring ketones.
- It’s straightforward to use and doesn’t require urine or blood.
How do breath ketone analyzers work?
They are very simple.
All you have to do is turn on the breathalyzer and then breathe into it for however long the manufacturer instructs (about 15 seconds).
Wait for a few seconds and then check the results.
What is the Best Way To Measure Ketosis?
This question has no clear answer, and it depends on what you’re looking for.
- Ketone Urine Strips: Very cheap but low in accuracy compared to the alternatives
- Blood Meters: Highest degree of accuracy at the highest price
- Breath Ketone Analyzer: Expensive, but you only pay once since it needs no ketone strips. Probably somewhere in the middle when it comes to accuracy.
Final Thoughts
Ketone strips are a reasonably accurate—and cheap—way to detect someone’s (approximate) state of ketosis.
For someone attempting to ‘enter’ therapeutic levels of ketosis, ketone testing is a valuable tool.
However, they are probably not necessary for the average person who just wants to lose a bit of weight or finds a keto diet beneficial.
That said, they can be a useful way to check that those new to ketogenic diets are on the right track.
For information on when excessive ketone levels can be an issue, see this ketoacidosis guide.
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61 thoughts on “Measuring Ketosis With Ketone Strips: Are They Accurate?”
Inaccuracy issues with keto strips do make sense. After all, the urine is never the truest indication of what’s going on in our bodies. It can help but it seems that the results should always be considered carefully.
Quite right – random tests don’t always tell the whole story.
The inconsistencies is these strips somewhat discourage some of us in using them because one can never tell ABSOLUTELY if they are right on point. All the same, I think they are pretty darn useful. Thanks for sharing this info Michael
That pretty much sums it up – they are useful, but (usually) not necessary!
Thank you very much! I was searching around the internet for “just simply stated” information and found it here. And another thank you for the Ketone Level Chart. Added it to my phone for ready reference at a glance!
Thanks, Luis! Hope you find them both useful.
I have been on a Keto diet for 8 weeks and I have lost 12 pounds. My Keto sticks always register negative. I figure if I am eating Keto foods and losing weight then I should not worry about the test strips. Your thoughts?
Absolutely, 100% agree. If you are losing weight and feeling healthy then that is the most important thing, not some random number.
Well done on your progress too – 12 pounds in 8 weeks is great!
I started the diet a month ago and tested for the first time today with urine strip. At (or above) 16 mmol/L. Far side of the stick. Still quite lethargic and even at times weak. I have lost weight and inches (quite a bit for 4 weeks), but am not eating much (compared to my prediet intake) due to small appetite and may be losing weight for that reason alone? I thought I would be adapted by now, but with reading this high in urine, is it likely I am not burning fat/ketones yet? I am not diabetic or prediabetic as far as I know. Should I worry about how high the number is this far into the diet?
Quite a lot of points here!
1) As stated, ketone strips can be unreliable… and it would be irresponsible of me to try to guess your exact situation, so if you have any concerns at all then I would recommend seeing a doctor and explaining everything and getting a quick check-up.
2) The weight loss is absolutely because of eating less. Generally, this is one of the positives about ketogenic diets; they seem to be really beneficial for satiation and people naturally reduce their total food consumption. Not always, but often.
3) Feeling weak/lethargic after 4 weeks isn’t good. As you said, it could be as because you are eating far too little calories, or it could just be that a ketogenic diet doesn’t really fit you. There’s no one diet to rule them all, and some people do better with a slightly higher carb intake.
Hi Diane,
I can’t give personalized advice, but here are some general things that people should be aware of:
1) Ketogenic diets can have positive effects, but they aren’t the right fit for everyone – some people do better with more carbs.
2) Some people don’t eat enough food when they switch to a keto diet – they cut carbs, but don’t properly replace them with enough fat/protein.
3) So-called “keto flu” can cause people to have certain side effects such as dizziness and lack of energy – consuming enough electrolyte minerals is important when people start ketogenic diets (https://www.nutritionadvance.com/keto-flu)
A few years ago, I was eating Keto. Felt great most of the time. At one point though, I get exhausted and lethargic. I went to my doctor and found I was anemic due to a lack of folic acid and vitamin b. I adjusted my diet to be carb light, not carb free by adding more fruits and vegetables with essential vitamins I needed. Michael is right, it’s all very personal, not one size fits all. I advise that you listen to your body, check in with your doctor and adjust your diet to what your body needs to operate best.
Thanks for the input, Tif.
Great (and sensible) comments too.
Hey Michael, thank you for sharing the information, a great read!
I’ve been using keto strips, and I realized that if I leave my tested strip out longer(say one minute), it becomes much darker–why is that? It makes me from being in very light ketosis(0.5) to light state(1.5 or more). Can you shed a light on this? This makes me question the accuracy of the strips, but also brings me hope…haha…
Thanks!
To be honest, I don’t know the exact reasons they get darker with longer lengths of time… but this is a common thing and always happens. As the pack will probably say, depending on the brand, an accurate reading will be given at 15 seconds! So, whatever color it is at that time will be the (most) accurate reading.
Been on a ketone diet 10 days now dropped 11lb so over the moon my levels are showin +++80 I just wanted to use strips to check I’m doing my diet right and they worked for me as they are showing what I expected for my results did have the bad head first two days but energy levels and me feeling great at the minute.
That sounds great, Michelle.
Glad it is working well so far, and congrats on your progress!
Hi and thanks for the advise , I got my Keto urine strips today and they say I’m at 8🤔I feel great have more energy and have lost 7 pounds in 5 days but IDK
Hi Cristy,
I would pay more attention to how you feel rather than the test score. If you feel great and you have lost weight, then that’s amazing. Well done!
Hi Michael,
I started my keto diet 10 days back , starting from keto Reboot and continued on a strict low carb diet…I have lost 5.6 kgs and feel energetic..just to test whether I was in the state of ketosis I bought ketostix and measured the level…most of the times I am getting the level of 80++ initially j was happy about it but when I went to internet it’s mentioned that it might be an indication of diabetes and other things like coma and higher level might proved fatal…please clarify?
Thanks
Hi Rajan,
It sounds like you were reading about something called ‘diabetic ketoacidosis.’
This is a potentially life-threatening condition that affects people with type 1 diabetes.
On the other hand, ketosis (in a healthy person) is very different. You can see a comparison between the two here: https://www.healthline.com/health/ketosis-vs-ketoacidosis
If you have any concerns about T1D or anything else, please see your doctor/healthcare team, explain about your diet and get tested. It is always better to be safe and sure.
Why do my ketostix always come up negative? My carbs have been kept below 30g/day and I’ve lost over 50lbs in less than 90 days I just don’t understand why the ketostix are not showing a positive reading.
Not sure – that sounds strange. Did you follow the product instructions exactly?
But either way, it is the outcome that is most important. If you are losing weight and making progress, then that is much more important than any random strip reading.
yes it doesn’t make any sense! I have tried both “Ketostix” and “True plus” Ketone test strips. both just opened with expiration dates of 12-31-2019 and 11-30-2019 respectively. I’ve used both with urine stream and sample cup methods and in every test it comes out negative. I ordered a blood ketone meter to see if I can get a reading that way. Is it possible my body has adapted and is using fats that efficiently or so completely to the point ketones in my blood just aren’t being expelled in my urine??? And is that a bad thing? I’m literally drinking gallons of water and taking potassium and magnesium supplements too. an average day is 1600 calories w/16g carbs, 125g fat, 95g protein, and sodium around 2800mgs. and my urine stream is very yellow most of the time. I just want to make sure I stay in ketosis so I don’t have to worry about muscle loss from reduced caloric intake. I have to add that a much as I enjoy a really good pizza I find fatty foods the most satisfying by far.
It could be like you said, and no that wouldn’t be a bad thing – it would just mean that your body is utilizing everything efficiently. However, I would still expect there to be at least some kind of positive result. There is also the issue that sometimes these strips can be unreliable, but if you have tested multiple times with different brands then this should be irrelevant. If you really wish to know, it might be worth taking a blood ketone test since this is more accurate.
If worried about muscle loss, I would say increasing protein intake would be the most evidence-based way to prevent catabolism.
yes but wouldn’t or couldn’t that (increased protein) be counterproductive with a LCHF diet since the body could actually convert proteins into carbs by a metabolic process called gluconeogenesis ? (just something I read) The blood ketone test kit I ordered will check Glucose also. My carb,fat,protein intake does change every day and some days my protein could be higher than my fat intakes too. I did an Atkins style low carb diet many years ago and went into ketosis quickly. Although I am losing weight this time as well I am having a hard time trying to figure out why I don’t seem to be in ketosis……….or at least why the ketone test strips keep coming back negative. I wish there was some common liquid like vinegar or something that you could just use to test the ketostix……! I’ll let you know how the blood ketone test works for me.
Gluconeogenesis is a thing, but it’s something that is often misunderstood and there are lots of myths which get widely repeated.
Have a look here: https://ketogains.com/2016/04/gluconeogenesis-wont-kick-you-out-ketosis/
Been doing keto for a month and lost 16lbs just got my urine strips today and they say I’m in the high range(80) not sure if that good or bad?
Hi Jaden,
It depends on what you are aiming for! If you are purposefully aiming to be strongly in ketosis, then that would be a good score. Many people do aim for around that area (50 – 80).
I started Keto almost 4 weeks ago. I have lost 15 lbs and stalled but have gone down a size on the stall. The Keto urine strip is always the same color moderate that really dark pink 4.0 range. Is that ok? I mean after reading your article I probably should just toss them. I did notice that when they are in the garbage the next day they are dark purple. Is it the same rule of thumb don’t read them again after initial result? Thank you!
Hi Jay,
Yes, if that is what you are aiming for. The test strips will show their most accurate reading after about 15 seconds, so anything after that will be unreliable.
I started keto around beginning of September and have lost about 13 pounds. I did a cheat day yesterday and had probably 100 carbs. and normally I never go over 50. I’m really good with this diet. But my keto level measured negative today. is this bad? Am I no longer in ketosis now?
Hi Leiah,
There are a few points in regard to this;
1) The readings can sometimes be inaccurate.
2) If you lower carbs again then the ketone readings should quickly go back to whatever they were.
3) Being “in ketosis” is just a natural process that happens when carbs are very low, but that doesn’t mean we need to be in it all the time. There is a lot of confusing information about this online, but if the diet is consistently working for health/weight loss, then that is much more important than ketone levels.
Thank-you! This was a very helpful, informative article for the average (learning how to navigate the Ketogenic diet strategy) guy. I’ve just used my first strip this morning and was curious/concerned that the reading of “SMALL” on the scale of NEGATIVE, TRACE, SMALL, MODERATE, LARGE, more LARGE was inadequate. But your information gives me some understanding that I may be headed in the right direction.
No problem! Glad it was useful for you.
Hi, i have been in keto diet for three week when i started i felt terrible. Upset stomach low blood presure, headache and palpitations. Second week i was feeling good but today i feel terrible again. Palpitations have not go away sience fisrt day. Knomd hands, face and legs with little ants walking all over, feel like. My test strip is always shown large number of keatones.
Hi Rebecca,
I would first consider whether the diet is right for you – there are many different ways of dieting, and if you don’t feel well on a sensibly planned keto diet it may be worth looking at something else.
If you want to stay on the diet or a reasonably low carb plan, it might be worth increasing carbohydrates a little and seeing how you feel.
Otherwise; many people feel symptoms during the first few weeks of a ketogenic diet, and this is often from a lack of electrolytes (magnesium, potassium, sodium). It might be a good idea to check with a doctor or work with a dietitian/nutritionist just to be safe.
Hi i started the keto diet a week ago and lost 7 lbs woth no effort. Have been being very strict with trying not to eat over 20 carbs a day. I bought the strips and every time i check i am on the large keto level. The very highest on the chart. I was alarmed and want to know if this is bad for my health as the optimal level on the chart is around the mid range on the chart. While i feel good and have good amounts of energy now i feel like i need more sleep at night and in evening get headaches. I did not go thru keto flu ….is this still to come? The very first night i felt sore but thats it.
Hi April,
Not everybody has the initial side effects on a keto diet (especially when the diet is well thought out), so if you didn’t get those symptoms then that’s great.
Needing more sleep at night and headaches could be lack of energy (are you getting enough food?) or potentially hydration/nutrient deficiencies for headaches. But there are many possible causes for lack of energy and headaches, so it’s hard to say for sure.
You could also increase the carbs a bit and see if that makes you feel better (unless you’re strictly limiting them for a specific reason/medical diet).
There are some resources discussing ketone level readings here:
https://diatribe.org/making-sense-ketones-diabetes
https://www.ketogenicforums.com/t/ketone-level-too-high/15623/8
The body should almost always regulate Ketone levels to stay within a safe level – the exception here is people with type 1 diabetes.
I’d suggest discussing the diet with a doctor if you have any concerns about either of these points.
You can also read the differences between ketosis (safe) and ketoacidosis (not safe) here: https://www.nutritionadvance.com/ketoacidosis-and-ketogenic-diets/
Hi! I started the keto diet, and it’s been one month and 1 week. I was showing high ketones level during the second week of keto, but when I checked today the level was small. I haven’t changed any food in my diet, and I haven’t had an increase in carbs. Any idea why this is?
Hi Maria,
There is no way to know for sure, unfortunately.
However, some studies show that the body gets more effective at using ketones for energy (i.e. burning fat for fuel) over time. In such cases, since more ketones are burned by the body after adapting to a ketogenic diet, fewer would be left over to be picked up by the test strip.
Things such as stress or lack of sleep can also raise cortisol which would reduce ketone levels.
There’s also the possibility that the strip gave a faulty reading. Sorry that there’s nothing more definite, but I hope this helps!
Thanks for this great article. I start water testing and I checked my keto level on 5th and 6th day. Both came out a little darker than moderate. Is this normal?
Thanks Sal! A little darker than moderate would make sense if you are eating a diet fairly low in carbohydrate.
Hi Michael,
I have been on the ruled me Keto diet for 10 days. Only lost 2 pounds. I test 4.0(moderate) on the Keto strip. Why am I not losing more weight?
Sorry Stacy, but this is very difficult to answer without knowing any details of the diet or existing stats.
For anyone following a weight loss diet but not losing weight, the most likely reason would be that overall food intake is too high. That said, 2 pounds of weight loss in 10 days sounds quite good – providing it isn’t just water weight, that would be about 6 lbs per month.
I have lost 3 pounds this week and I took the ketosis urine test it said I had a small amount of ketosis! I feel good though lots of energy and my daughter and I even went for a walk around the nieghborhood last night for over a hour. I get really hungry around bedtime but force myself to just go to sleep. I dont usually wake up hungry in the mornings though it’s weird. Any advice for my night cravings.
I’m not sure – are you eating enough during the day? If feeling hungry at night time, upping protein intake a little could help (protein tends to be the most satiating macronutrient), or possibly making dinner slightly later (depending on when you already have it).
You could have a small protein snack to satisfy that.
Maybe a little peanut butter or ham and cheese. Depending where your at on your carb count, low sugar yogurt. Or even drinking something could help. Low sugar/no sugar hot chocolate, almond milk. I guess list could go on. Lol. Good luck 👍
Thank you for the information. I have been on Keto for about a month and I have lost about 10 pounds. I use the keto sticks and I am all over the place with them as I use them frequently. Sometimes I register and sometimes I don’t. Most recently I have not been registering at all which is why I am looking for information. I haven’t registered on the stick in 3 days and then all of a sudden today I am showing a slight amount. After reading this I ordered the keto blood test kit and I will have my answer soon, but any insight would be great.
Hi Theresa,
It’s really difficult to have an insight into this because so many different things could have had an effect here. For example, a lack of sleep over the preceding days or a slight dietary change? Providing you don’t need to maintain a specific ketone reading for medical reasons/doctor’s advice, I would say that an inconsistent ketone reading isn’t a big deal providing other markers are OK. For instance, if you’re trying to lose weight or trying to keep blood glucose down….if it’s going well, that’s more important than a specific ketone reading.
Thank you so much Michael Joseph. This is a very helpful article. Thanks for your insights!!! excellent article.
Thanks mamatha, glad it helped!
Hi I have been reading negative on the pee strips is that good or bad.
It’s not necessarily good or bad… it depends what you are aiming for. The accuracy of the tests can be questionable, and I would say other markers of health (and how you feel) is more important than a ketone score.
Hi! I have been wondering what the best time is to take a ketone indicator test. Fasting? After a meal? After a workout? I just want to know what would be the most “accurate.” I know that it’s all pretty relative to individual bodies, but I don’t know what is considered “best.”
Hi Taylor!
Generally speaking, doing a test first thing in the morning would probably give the most reliable results.
Research suggests that either this time or late at night (at least a few hours after the last meal) is the most accurate. (Ref: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5097355/)
My strip is the darkest purple is that good
The darker purple, the more ketones. Whether that is good or bad depends somewhat on the individual, and whether that is what you are aiming for?
Mines also! Only 5 days in, so maybe that is why. I tested twice, same dark dark purple. Not a diabetic.
Hello Michael! Your article was very informative. I know I have read your answers a few times but I have to ask… I started a week and a half ago. I was reading ketones on the urine strips and have now stopped. I read either negative or slight. I understand that your body starts to use the keytones so you may not see them reading on the strips, but should that happen this quickly? Is there other concrete ways to know if I am in ketosis or not?
Hi Nicole, thanks for the comment! I don’t think you can really attribute a set time to this, unfortunately, and everyone will be different. But yes, there are more accurate (but more invasive) ways to measure ketone levels. The most accurate way at home would be by using a blood glucose & ketone meter, there is a very well-rated one called ‘Precision Xtra’ which you can find online for reasonably cheap.
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