A common goal for people on a keto diet is to achieve ketosis, which is a natural state where your body burns fat for fuel. However, it can be difficult to determine if your diet needs to be adjusted to achieve and maintain a state of ketosis. For this reason, many people use keto test strips. This article explains everything about how to use ketosis test strips to measure ketosis.
What is Ketosis?
Anyone following a standard high carbohydrate diet will burn glucose for energy. However, the body can use both carbohydrates and fats as fuel. When carbohydrate intake is low, the body turns to burning fat for energy. When this happens, our body enters a state of ketosis.
Ketosis is a natural biological state during which our body burns fat as fuel. When we are in a state of “ketosis,” the levels of ketone bodies – a byproduct of fat breakdown – in our blood rise.
Therefore, measuring these ketones (also known as “ketone bodies”) can provide an indication of the depth of ketosis our bodies are (or are not) in. For this reason, keto strips, which measure ketone levels, have become increasingly popular recently.
What are Ketone Test Strips?
When talking about keto test strips, most people are referring to paper test strips that test for ketones in the urine. These products are available over the counter, in pharmacies and online.
Ketone test strips were originally for people with type I diabetes, who tend to be at higher risk for ketoacidosis – a life-threatening condition in which ketone bodies reach dangerously high levels and make the blood acidic. However, in healthy people, the risk of ketoacidosis is extremely low, so if you are not diabetic, there is no need to worry.
But if you are diabetic, ketone test strips can be an easy way for you to monitor your health. However, a blood test would still be a more accurate way to do this. When doctors measure blood ketone bodies, this is how they interpret the results:
- Below 0.5 mmol/L – normal
- Between 0.5-3 mmol/L – nutritional ketosis
- Over 3 mmol/L – high ketone levels
- Over 5 mmol/L – dangerously high and indicative of ketoacidosis
Keep in mind that the values used on the ketone strips are different from the values mentioned above. Most of the time, you want to look for a change in color on the test strips and compare the results to the color chart that comes with the kit. A light pink color means you have low levels of ketone bodies in your urine, while a dark purple color means the opposite.
There are two other ways to test for ketones: with a blood ketone meter and a ketone breathalyzer. Both are more expensive than ketone urine test strips, but they are also more accurate.
The blood ketone meter is one of the most expensive. Not only does the actual meter cost $50-$100, but the test strips that go with it are also expensive. However, you do get a bargain because these tests detect beta-hydroxybutyric acid – the most metabolically active ketone bodies.
On the other hand, ketone breathlyzers are cheaper, but not as accurate as ketone meters. These devices only detect acetone in the breath, but this does not make them any less accurate. Studies have shown that acetone in breath is directly correlated with beta-hydroxybutyrate4 in the blood.
Another way to detect acetone in the breath is by smell. Acetone is a byproduct of beta-hydroxybutyric acid, a highly volatile compound. When released through the breath, it gives off a nail polish smell, which some people also describe as “fruity”. If you’ve noticed an unpleasant fruity scent lately – it could be a sign of ketosis.
How do Keto Strips Work?
Urine tests are similar to pregnancy tests, except they measure acetoacetic acid, a specific type of ketone.
Typically, you would dip the test strip into a cup of urine for a certain amount of time. The test strips are made of a type of paper that reacts to ketone bodies and will turn a different color. You will then match the color on your test strip to the accompanying color chart, which provides an estimate of your ketosis level. Typically, the darker the color, the more advanced you are into ketosis.
The urine level usually indicates the level in the blood. Ketone bodies in the blood should be measured to at least 0.5 mmol/dL, but numbers between 1.5 and 3.0 mmol/dL are optimal.
Blood ketone strips are similar to urine, except that you need to prick your finger to get a blood sample.
Measuring ketosis can also be done with a handheld device called a breath meter or analyzer. And you simply blow into a tube attached to the device to get a quick reading. What does this measure? Acetone (Ace), the third and least abundant ketone, is released through your breath. Like the urine test, the breath test is affordable, although it has the disadvantage of being less accurate. However, if you are new to ketones and want a non-invasive, convenient way to test without regard to location or time, then a breath test is a practical option.
How Accurate are Keto Strips?
During the first few weeks of entering ketosis, urine test strips are a good tool to measure whether you are in ketosis.
During this time, your body is not able to use ketone bodies effectively as energy, so you will excrete many of them.
But as you get deeper into ketosis, your body adapts to using ketones as fuel and becomes more optimized at producing ketones, with fewer unused ketones.
In other words, if you’ve been in a keto-adapted state for several months, ketosis test strips may show that your urine contains only trace amounts of ketone bodies, if any at all. This can mislead people into thinking they are no longer in ketosis, which may not be the case.
Nonetheless, when you are just starting a keto diet, using urine test strips is an easy and affordable way to see if your ketone levels are rising.
On the other hand, if you’ve been following a ketogenic diet for a few months and want to get a more accurate picture of your ketone levels, blood ketone strips are a more appropriate option.
However, it’s important to consider the higher price of blood strips and whether you want to prick your finger every time you measure your ketone levels.
How to Use Urine Test Strips on a Keto Diet?
Step 1: Wash your hands.
Step 2: Pee in a small, clean container and then dip the end of the test strip into the urine sample. Alternatively, you can pass one end of the test strip briefly through your urine stream.
Step 3: Wait a few seconds (or follow the instructions on the test package) and allow the end of the test strip to change color.
Step 4: Compare the color with the color chart on the test package.
Step 5: Discard the urine testing strip. Then wash your hands.
When is the Best Time to Measure Ketones in Urine?
A quick search for the ideal time to test for ketones can generate dozens of assumptions and a great deal of confusion. Given the natural oscillations of ketone levels, hormones and food intake throughout the day, when exactly should you test your urine to see if you’re in ketosis?
The best available data on this topic comes from a 2016 study that was specifically designed to find the best time to test for urine ketosis.
The subjects in this study were already in stable ketosis (confirmed by blood ketone body testing after completing a five-week keto diet). They performed eight urine ketone body tests in one day and 18 blood ketone body level tests in the same 24-hour period.
After analyzing the blood and urine ketone body results, they found that the most reliable urine tests were from the first morning urine and 3-4 hours after dinner.
In contrast, the least reliable timeframe was from shortly after breakfast to dinner. This is likely because their diet was formulated to maintain weight and they ate a keto meal or snack every 3 hours (starting with breakfast at 8am).
Even if your eating habits are very different from the subjects in this study, these results demonstrate a keto testing principle that can be available for any different keto diet. Wait at least 3 hours before testing to finish your last bite of food.
What Level of Ketone Bodies is Best for Health?
For those aiming for ketosis, what kind of readings should we aim for?
I have a feeling that many people look at this table and automatically assume that “strong” is best.
However, for the average person just trying to take care of their health – or maybe trying to lose some weight – a higher level is completely unnecessary.
If you are in the ‘light’ range, then your body will be burning fat for fuel and your ketone levels will be many times higher than the average person’s.
In short, aiming for a random ‘optimal’ ketone body number is not the right approach.
Listen to your body and see how you feel. That’s the right way to go.
Note: If you are on a ketogenic diet for medical purposes, discuss this with your doctor. Therapeutic ketosis levels can be very different from what the average person needs.
If you follow a very low carb ketogenic diet, there is no easier way to know if you are in ketosis than by using ketone strips. They are inexpensive and perfect for people new to the keto diet, as well as those who have taken a break from the diet and want to get back into ketosis.
For optimal ketosis, ketone levels in the range of 0.5-2 mmol/L are a good range for weight loss and overall health. However, going beyond this range is often unsustainable and unnecessary (unless prescribed and closely monitored by your healthcare provider for medical reasons).