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3 ways to measure ketone levels: which is the best?

Last updated: Aug 21, 2019 at 4:08PM | - Published on: Oct 3, 2018

Written by Sarah Neidler, PhD

Scientifically Reviewed by  Raphael Sirtoli, MSc

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We have been told our whole life that our body needs sugar as energy, even though there is a much more efficient source of energy: ketones. Our body produces ketones when carbohydrates are very limited. You can reach the state of ketosis by fasting or by eating primarily foods that are rich in fat and very low in carbs. Could this be you?

One week ago you were very determined to start the keto diet. Because you tried to remove temptations as far as possible, you cleaned your kitchen and got rid of all “forbidden” foods that don’t belong to a ketogenic diet.

You discarded or gave away pasta, potatoes, sweets, your favorite Amy’s frozen pizza, and other ready meals, oxidized seed oils, sugar and flour.

You went shopping and stocked-up with butter, coconut oil, and whole eggs. You also bought beef, chicken, lamb and mackerel and some leafy green vegetables such as kale and spinach. You are sure you ate less than 20g carbs per day but are you really in ketosis?

If you ate a lot of carbs before, it is likely that you went through the well-known keto-flu. You felt very weak and tired, had headaches and were not able to think clearly.

The keto-flu is however not a proof that you are in ketosis. ’As soon as you reduce your body’s usual source of energy, it’s likely you’ll feel weak while you adapt to your new main energy source (fat) in the meantime.

This also happens on a low-carb non-keto diet, where you eat a lot more carbs.

How do I know if I am in ketosis?

When in ketosis, many people perceive increased levels of energy, higher concentration, and less hunger. It might, however, take a few weeks to months before you really, fully, benefit from your diet change. So how do you know if you are already in the seemingly magical state of ketosis?

When you just started eating keto, you will probably notice some drastic changes in your body:

  • Some people report feeling thirstier than usual. This could be because your body is responding to losing ‘water weight’ or because you’re eating more protein than on your previous diet.
  • When you drink more, you go to the bathroom more – even several times per hour.
  • You will start having bad breath. You might not notice this yourself, but people around you will. Sympathizers of the keto diet describe this smell as sweet or fruity, but it is rather unpleasant, to be honest.

Less appetite is also a sign of ketosis that you will notice very soon. It may even be most obvious at the beginning, and your healthy appetite will quickly come back.

One thing you will notice for sure: You might not eat less on a per meal basis while being in ketosis, but you’ll probably feel like eating less frequently.

Hence the common reports of people going from 3 – 4 meals a day to an average of 2 after switching from a standard American diet to a ketogenic one.

You have been thinking about what to eat as a snack in between meals? If you eat one or two big meals a day, you won’t need a third meal and not even any snacks.

After a few weeks on a keto diet you will probably start having more energy, need less sleep, and you might feel the urge to exercise more. You usually don’t exercise? Better get your gym membership ready.

You will also notice an increased mental clarity, better concentration, and improved memory.

The signs of ketosis are usually pretty obvious, but you still may want to have a yes or no result that is as clear as black and white. Measuring ketone levels is especially useful in the beginning when you don’t know how it “feels” to be in ketosis. It also helps you to find the amount of carbohydrates that you can tolerate without falling out of ketosis.

Did you know?

‘Ketogenesis’ means making new ketones. We do this mainly in our liver, although some of our brain cells can do it too. Focusing on ketogenesis in the liver, we first make the ketone acetoacetate (AcAc) from our body fat, and turn most of AcAc into the other ketone beta-hydroxybutyrate (BHB).

BHB is the ketone you measure with a blood ketone strip. It then circulates in our blood ready to be turned back into AcAc by enzymes to participate in energy production (more ATP).

AcAc is the ketone you measure with urine strips. Without the help of any enzymes, AcAc can also spontaneously turn into the third kind of ketone called acetone, the one you measure in your breath with a Ketonix like device.

Ketogenesis is a crucial metabolic step your body performs and it’s being studied to find new drug and lifestyle interventions that make the most of this pathway to benefit your health and performance.

How to measure ketones

There are three ways to measure ketones in your body. Before we go into the details, if you can’t physically measure your ketones then the next best thing is using our mobile app Nutrita for its Keto score feature helping you choose foods that keep you in nutritional ketosis.

Nutrita’s Keto score uses an in-house formula to score how ketogenic a certain food is. Just scan it right in the grocery store or search for it in our database ang get an answer.

With a record of your purchases and meals you can see straight away if you’re following a well-formulated ketogenic diet. With our Keto score and your in-app ability to track biomarkers like blood BHB in-app, following a keto diet has never been easier.

Here’s a summary of the advantages and disadvantages of each method to measure ketones:

  1. Urine sticks – they are cheap and easy to use, but not very accurate.
  2. Breath meters  more accurate than urine sticks and affordable.
  3. Blood ketone meter –  very expensive, but the most accurate method. It is considered the “gold-standard”.

Ketone measurement in the urine

Ketones measurement in urine is done through acetoacetate test. With a single strip you can get your ketone levels in urines. It’s not the most accurate form of ketone measurement but worth a try

Acetoacetate is the first ketone that is generated from fatty acids. It can easily be converted into another ketone body, Beta-hydroxybutyrate (BHB). BHB and Acetoacetate are two energy-rich ketones that are generated in the liver and that provide your brain and the rest of your body with energy while being in ketosis.

When you just started on a ketogenic diet, urine sticks like Keto-Diastix® are the way to go. They are incredibly easy to use: you hold the stick into the stream of urine, and within 15 seconds you will know if your body is producing ketones.

The stick will show a color anywhere between light pink and maroon, and the darker the color, the more ketones. You should not get hung up on the exact color because the measurement is not very accurate.

If you drink a lot, this will dilute your urine, and the color will be lighter even though you produce a decent amount of ketones. Also, if you have in ketosis for a while, the sticks will show a weaker result.

Don’t worry that’s actually a good sign: that means that your body uses the ketones as an energy source instead of excreting them.

To summarize: urine sticks are a cheap and handy option in the beginning. On the other hand, they don’t accurately quantify how “deep” you are in ketosis.

Ketone measurement in the breath

Ketones measurement in breath is done through acetone test. You simply blow in a single stick from ketonix for example. Breath ketone is the more convenient one compare to BHB blood ketone test.

Acetone is the smallest of the three ketone bodies, and it is created spontaneously through the breakdown of acetoacetate.

Yes, correct. The nail polish remover ingredient is a ketone. Acetone is a byproduct of ketosis and exhaled through the lungs. It’s the acetone that gives your breath that distinctive smell.

You can measure the acetone in your breath with a breath meter called Ketonix. It is more accurate than urine sticks but much less accurate that BHB measurement in the blood. It is easy to use and very affordable in the long run.

In the beginning, you have to buy the device, but you don’t have to pay for individual tests. So like the urine sticks, a breath meter will tell you if you are in ketosis, but not how “deep”. If you plan to follow the ketogenic diet for a longer time, it’s definitely worth the investment.

Ketone measurement in the blood

Ketones measurement in the blood is done through BHB measure(beta-hydroxybutyrate) With a device called ketone meter like keto mojo you can use ketone strip to measure your blood ketone

Measuring ketone bodies in the blood is considered the “gold standard”. Acetoacetate and BHB can be detected in the blood, but usually, BHB is measured.

Measurement of BHB levels in the blood is very accurate and gives results in real-time. One commonly used device is Keto Mojo that also allows you to measure glucose levels.

This kind of measurement is very accurate, but the ketone strips are quite expensive. When you follow a ketogenic diet, you can expect values between 0.5 and 3.0 mmol/L.

Under 0.5mmol your are burning carbs, near 0.5 mmol would be considered as mild ketosis, whereas 3.0 mmol/L is considered deep ketosis. Some people can get as high as 5 – 6 mmol/L when eating a large caloric surplus of fat or when fasting for multiple days.

To summarize: The most accurate method to measure ketone levels, but very expensive. Some people need exact measurements for medical reasons.

Which ketone measurement is best?

Which method is most suitable for you depends on your goals. If you just need a “yes” or “no” answer shortly after having started the ketogenic diet, urine sticks are the best option.

They are cheap, and you don’t have to invest in a measuring device. If you know that you will follow the ketogenic diet long-term, you may want to invest in a breath meter.

This will also give you a “yes” or “no” result. Measurement in the blood is most accurate but also the most expensive option.

How often should you measure?

If you don’t follow the ketogenic diet for medical reasons, that’s really up to you. Shortly after changing your diet, measuring is very useful to be sure that you are in ketosis.

When you want to test how far you can increase your daily carb intake without being kicked out of ketosis, measurement is also very helpful.

When starting keto, it is recommended to stay below 20g of carbs per day. Over time when you become well adapted, and your body got used to using ketones as fuel, you can eat up to 40g or 50g of carbs.

If you do a lot of high-intensity exercises, you can push up your carbs even further (avoid flours and sodas though!). When you have been in ketosis for a while, it will be enough to measure every few weeks.

Trust me, you will get a feeling for it over time. But you may want to measure when you notice a change in your body. Imagine, you have been in ketosis for several months, everything goes smoothly, you feel great and burst with energy.

At some point, you notice that you feel less energetic and get tired more easily? That would be the time to measure again. We tend to get a bit sloppy over time and unconsciously sneak in some hidden carbs into our diet.

For those of us who aren’t very insulin sensitive a little milk and sugar in the morning coffee, tomatoes in your lunch and strawberries as dessert – it all adds up. Being able to measure ketone levels will bring you back to reality.

Who should measure ketone levels?

A ketogenic diet is beneficial in the management of certain conditions, such as metabolic syndrome,diabetes,and obesity.Metabolic syndromeis a pathologic state of metabolism, and it is associated with an increased incidence of heart disease, diabetes, obesity, and cancer. 

Increased fasting glucose levels and high blood pressure are two measures to diagnose metabolic syndrome, among others. Metabolic syndrome is also seen as a predictor for diabetes.

A low carbohydrate or ketogenic diet is a lifestyle intervention that helps to improve metabolic syndrome and possibly to prevent diabetes.

Many people also find it easy to lose weight on a ketogenic diet, even obese people successfully lose vast amounts of weight.

People who follow a ketogenic diet for medical reasons should regularly measure their ketone levels to make sure they stay in ketosis.Diabetes patients have an additional reason to measure ketone levels even when they don’t follow a ketogenic diet. 

They are at risk to develop diabetic ketoacidosis (DKA). When insulin is not able to control blood sugar nor blood BHB levels, they rise to dangerous even life-threatening levels. 

Diabetes patients, for this reason, need an accurate measurement of BHB levels in the blood. If they’re eating a standard american diet high in in carbohydrates,there blood BHB levels will be well below < 0.5 mmol/L. 

So in this context, if their blood BHB levels start to steadily rise above that then to 3.0 mmol/L then they’re probably in dangerous DKA territory.

Do ketone levels correlate to weight loss?

Being in ketosis means that your body can efficiently burn fat and use it as fuel but the amount of ketones you produce does not correlate to weight loss.

On the other hand, being able to use fat as fuel is also the first step inburning body fat. Body fat is less accessible than the fat in your diet, but your body will more easily burn body fat as fuel while in ketosis.

The main reason why it is easy to lose weight on a ketogenic diet is the normalization of the appetite. You don’t feel the need to overeat when you are in ketosis, and this will prevent you from eating more than your body requires.

Nobody can stand being hungry over a long period of time, and the keto diet allows you to lose weight without being hungry.

The other reason is that ketogenic diets could be changing your ‘metabolic settings’ just enough to increase your net daily caloric expenditure compared to a low-fat diet – with potentially fat-loss aiding effects over the long-term.

Maybe it’s both. Hard to say but either way, it seems to be helping a growing number of people normalize their body composition and appetite.

Optimizing ketosis with Nutrita

Nutrita provides you with an Insulin index as well as Keto and Nutrient density scores. This helps you to make healthy food choices and to stay in ketosis.

This means eating nutrient dense foods, meeting your high-quality protein needs and making sure your inflammation is kept to a minimum by avoiding refined sugars, seed oils and flour products.

A ketogenic diet is a bit of a learning curve for many people so Nutrita allows you to easily learn from other users, like what they’re eating, what their ketone levels are, whether or not they’re making progress reversing their diabetes or obesity.

They might not be eating a ketogenic diet and getting good results anyways – good to know right?

Most people use food tracking apps for fat-loss so we want our users to know that calorie restriction alone miserably fails as a strategy for fat-loss: after 2 years 95% of people re-gain their lost fat or pack even more on! This is why Nutrita uses different, better metrics and can help you achieve your dietary, health or performance goals.

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Written by Sarah Neidler, PhD

Sarah Neidler did her PhD in cancer research at the Beatson Institute for Cancer Research in Glasgow. She has a strong interest in nutrition and the ketogenic diet and believes that they are beneficial for the treatment and prevention of chronic conditions, such as heart disease and diabetes. She loves cooking, reading, sewing, Yoga, and CrossFit.