How To Measure Ketones and Know You’re In Ketosis

The whole point of embarking on the Ketogenic diet is to shift your metabolic state into ketosis. Through careful planning, tracking macros, as well as best efforts to cut the carbs; your goal is to reach a state of ketosis - and stay there.

In ketosis, your body produces ketones as a by-product of burning fat for fuel.  Ketones are essentially the biomarker for ketosis. Since there’s no other way of knowing for certain if you’re in ketosis; measuring ketones will let you know for definite if you’ve reached the ultimate goal of going Keto.

So how do you go about measuring your ketones? There are 3 typical ways to measure, each with their own pros and cons. Let’s take a closer look.

What Are Ketones?

Simply, ketones are a chemical the liver produces when it breaks down fats.  Ketone bodies are a by-product of being in nutritional ketosis. Without carbohydrates, your body will use ketones for energy instead of glucose.

Even the name ‘Ketogenic diet’, is a nod to this very chemical reaction and the presence of ketones in your body.

The amount of ketones in your body is a pretty big deal for Keto-ers, and to be sure of reaching your goal, you will want to measure your ketone levels.

There are three different ways you can go about measuring and following your ketone levels: through your blood, urine or breath. There are three different devices and techniques depending on which method you choose.

Ketones In Urine

Measuring the level of ketones in your urine will give you a good idea of the amount of ketones in your system over the last few hours. It works by measuring the level of acetoacetate in your urine - a biomarker for the level of ketones.

It’s relatively simple and affordable to test the level of ketones in your urine. You will need to purchase some urine ketone strips, which are readily available online or at your local pharmacy. They’re pretty cheap at around £10 for 200 strips.

To use, you will need to urinate into a suitable cup or directly onto the test strips - whichever you prefer. After 30 seconds to a minute, your test strip will change colour and you will be able to read the strip.  

It’s straightforward - you compare the colour of your used test strip against the scale provided on the bottle/leaflet that accompanies the ketone test strips. If your strip does not change colour, this indicates you do not have a detectable amount of acetoacetate in your urine and are not in ketosis.

Urine ketone test strips are an easy and affordable way to measure your ketone levels.  However they do not provide real-time results nor give you 100% accuracy. They can also be messy and impractical. 

Ketones In Blood

Testing for ketones in your blood gives you real-time results. You can purchase a blood ketone meter online or in large chemist stores, and they’ll set you back in the range of £25-£75 depending on the model you choose. Additional testing strips are more costly working out at around £1 per strip.

Blood ketone meters measure the amount of β-hydroxybutyrate present in your blood which indicates the concentration of ketones in mmol/L (millimoles per litre). The results are very accurate and simple to read via the screen on the blood ketone meter.

To use the blood ketone meter you will need to draw blood from your finger using a lancet - a small tool with a sharp needle-like point with which to prick your finger and draw blood. A little tip: It’s easier to place your testing strip into the testing meter before placing a drop of your blood onto the test strip! Your results will appear clearly via the screen within seconds.

This method of measuring your ketone levels is quick and accurate, but not without pain or expense.

Ketones In Breath

Measuring ketone levels through your breath can be done using a ketone breath meter. The results are quick and easy - you simply breathe into the device and it measures the amount of acetone in your breath. Acetone in your breath is another biomarker of ketones in your body; produced as a by-product of using ketones for fuel.

The breath sensor works by using nanosensors to detect the amount of acetone present in your breath at a concentration of 1-2 parts per million. The reading is given promptly via the screen without fuss or pain. 

However, this technology doesn't come cheap; ranging from £30-£200 per device. The more expensive the sensor you choose, the more likely it is to be accurate.  You won’t need to pay out for additional accessories, but the initial outlay is greater. If you opt to use a cheap version to save money, you risk inaccurate results.

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Interpreting Your Ketone Reading

Whichever tool you use to measure your ketone levels, you’ll want to understand what the reading means for ketosis. Each method described detects different biomarkers and uses different measurements to provide you with a ketone level reading.

If you’re using a blood ketone meter, the ideal level for nutritional ketosis is 1-2.5 mmol/L, but the levels can range from 0 to 3. Less than 0.5 means you’re not yet in ketosis, more than 3 can be dangerous. Too high and your body is not using ketones efficiently and/or your body is struggling to function due to consuming too much fat or entering starvation mode.

A breath sensor monitor will measure acetone levels and the range can be anything from 2-40ppm. The optimum range you will want to see on your reading to indicate nutritional ketosis is anywhere between 4-30ppm. This range is equivalent to the 0.5-3 mmol/L indicated by blood ketone meters.

Urine test strips read altogether differently - you need to read and compare the colour with the colour chart provided. You can find out if you have small, moderate or large amounts of ketones in your body using the urine markers, the equivalents are as follows:

Therefore you’ll be aiming to see ‘small’ to ‘moderate’ amounts of ketones in your urine to be sure you’re maintaining optimum nutritional ketosis.

Keeping Ketosis

In summary, there are 3 main ways you can test your ketone levels to determine if you’ve reached the ultimate goal of Keto - ketosis.

You can test with your urine, blood or breath using ketone test kits readily available online or in larger pharmacies. The least fussy option is also the most expensive - the breath ketone monitor. If you have the money to invest this can be a great tool, but don’t bother relying on one that comes cheap.

Likewise urine keto tests are affordable but less accurate, although they’re a great option to find out if you’re hitting ketosis when you first start out. Blood ketone tests are reliably accurate and the middle of the road when it comes to cost, but require a little discomfort.

Whichever method you choose to use, testing your ketones consistently can give you surety that your Keto diet is paying off - that you're reaching ketosis and staying there. You can be confident that you’ve successfully reached your Keto goal and the health benefits will soon be felt and seen.