Ketone testing is a method of objective feedback for those starting a keto diet. Ketones, which show up in urine, blood, and breath, are concrete measurements of progress. Ketone levels for ketosis are a tool to help people evaluate and adjust their eating habits as they follow their keto journey.
What are Ketone Strips?
Ketosis strips are small slips of paper that measure the amount of ketone in your urine. They are readily available at drugstores and large pharmacies, typically found in the dietary supply section or a section dedicated to diabetic medical equipment. Ketone strips will also be available in the pharmacy section of most large grocery stores.
How do Ketone Strips Work?
Ketone test strips are made from a type of paper that changes color as it reacts with your urine. Ketosis urine strips employ a color-coding system to indicate the level of ketones in your urine. The strips have a small absorptive pad at one end, which you place in your urine stream. Every manufacturer is a little different, but typically, the fewer ketones you have, the lighter the color will be on the test strip. Similarly, the more concentrated your urine is with ketones, the darker the test strip will be.
How to Use Ketone Strips
- Collect a Urine Sample (Optional): Urinate into a disposable plastic cup to collect the urine sample. You can purchase disposable plastic cups at any grocery store.
- Dip the Strip: Dip about 1⁄4 inch (0.64 cm) of the chemically sensitive end of the strip in a urine sample or urinate directly on the strip. Be sure to dip in the tip that contains the ketone-sensing chemicals. For most individuals, it's easiest simply to urinate directly onto the strip. Do this over a toilet. If you're urinating while seated, try not to dip the ketone strip into the toilet water.
- Wait: Follow the directions printed on the side of the packaging, which will tell you how long you should wait. Typically, you need to wait 40 seconds (or the time indicated on the packaging) for the strip to change color. As your urine reacts with the chemicals on the urine strip, the strip will turn a yellow, maroon, or purple color.
- Compare the Color: Compare the color of the strip to the indicators on the packaging to find your ketone level. The ketone-strip container will have a series of colored squares on one side. It may be the case that the color of your urine strips fits in between 2 of the color squares on the packaging. Once you've matched your urine-strip color with a color square, look closely to find the number and description that correlate with the color. The colors will also correspond to numerical values: 0.5, 1.5, 4.0, etc.
Interpreting the Results
High levels of ketones in urine indicate high amounts of fats in the urine, which indicates that the keto diet is having its desired effect.
Color Chart and Ketone Levels
The color of the strip corresponds to a range of ketone levels. Here's a general guide:
Read also: Easy Low-Carb Cheese Crackers
- Light Colors: Indicate a lower level of ketosis.
- Darker Colors: Suggest a higher level of ketosis.
If you've recently started a keto diet, your body will be eliminating large amounts of ketones through the urine. This will result in a deep, maroon-colored urine strip, which correlates to a “Large” amount of ketones in your urine. When you begin a ketone diet, your ketone strip will turn a dark maroon or purple. By the time you're a few months into the diet, though, your urine-strip results will lighten, and may only indicate a “Moderate” amount of ketone in your urine.
For optimal ketosis, ketone levels of 0.5-2 mmol/L are a good range for weight loss and overall health.
Factors Affecting Ketone Levels
Several factors can influence ketone levels:
- Adaptation: As you maintain a ketogenic lifestyle, your body adapts, and with that, it becomes more effective in utilizing ketones as its fuel source. Meaning, ketones are less likely to spill over into your urine.
- Dehydration: One randomized controlled trial found a direct proportion between serum ketone concentration and the level of dehydration.
- Expired Test Strips: Check the expiration date of your urine test strips. Strips usually expire within 3-6 months after you open the sealed bottle container.
- Time of Day: If you’re new to keto and are trying to determine how deep into ketosis you are, it’s best to test at the same time every day. Since your hydration level plays a role in your test results, it’s best to test at a time when your hydration will be relatively the same each day.
- Foods and Beverages: Foods and beverages can create harmless color changes in your urine that have nothing to do with ketosis. For instance, some people find that when they consume a large amount of beets, it shows up in their urine as a light pink color.
Optimal Ketone Levels Based on Goals
The optimal ketone level will be different if your goal is to lose weight than it is if you want to prevent illness, improve mental clarity, or become more physically fit.
- Weight Loss: If your primary goal for integrating the ketogenic diet into your life is weight loss, achieving “light nutritional ketosis,” or 0.5 mmol/L-1.0 mmol/L, is a good starting point. From there, aim for “optimal ketosis,” which is when your ketone levels are between 1.0 mmol/L-3.0 mmol/L.
- Therapeutic Benefits: People looking to use the ketogenic diet for therapeutic benefits for medical conditions such as epilepsy, cancer, or endocrine and metabolic disorders, are generally directed to aim for much higher ketone levels-specifically in the 3.0 mmol/L -5.0 mmol/L range, or somewhere between. Those who are fasting or eat a much higher fat-to-protein ratio will look to levels in the 3.0 mmol/L-8.0 mmol/L range. But you don’t need to go there.
Exercise and Ketone Levels
Yes, but the effects differ from one person to the next. Still, generally speaking, anaerobic exercise (usually short duration and high intensity, like heavy weight training, sprinting, or jumping) will decrease circulating ketones, cause blood glucose to go up slightly, and cause ketones to temporarily go down. With aerobic exercises, such as swimming, walking, jogging, and cycling, you’ll generally notice an increase in circulating ketones. Does this mean you do not want to do anaerobic exercise while on a ketogenic diet? Absolutely not!
Read also: Keto Calorie Counting: A Detailed Guide
Limitations of Urine Ketone Strips
Of all the ways to test ketones, urine test strips tend to provide the least accurate results. This is due to a number of reasons, one of them being the switch to BHB, as previously mentioned.
Acetoacetate vs. BHB
Ketone urine strips only test for the ketone body acetoacetate. As you get deeper into ketosis and become keto-adapted, your body will begin to efficiently convert acetoacetate and, as a result, produce more of the ketone beta-hydroxybutyrate (BHB), which cannot be detected using urine test strips. For this reason, experienced keto dieters who have been in ketosis for a while may present with very few ketones on their test strips. In this case, it’s best to switch over to a more accurate method that measures BHB, such as a blood test.
Accuracy in Detecting Mild Ketosis
Urine dipsticks are not an accurate or clinically useful means of detecting mild ketosis in people undergoing a severely energy‐restricted diet and should thus not be recommended in clinical treatment protocols.
A study showed that urine dipsticks are not an accurate or clinically useful way of detecting mild ketosis in people undergoing severely energy‐restricted diets. Urine dipsticks had low sensitivity for identifying when participants were in mild ketosis (as defined by blood β‐hydroxybutyrate concentrations being ≥0.3 and ≥0.5mM), because in only 35% and 52% of those occasions, respectively, did their urine test positive for the presence of ketones with the dipstick. This means that for 48% to 65% of the times when participants were actually in ketosis, as defined by their blood β‐hydroxybutyrate concentrations being at or over these 0.3 and 0.5mM thresholds, the urine dipstick indicated that they were not in ketosis. That is, the rate of ‘false negative’ results were 48% to 65%. Even at a higher threshold for defining ketosis (ie, ≥1.0mM β‐hydroxybutyrate in blood), urine dipsticks still had unacceptably low sensitivity: They only detected the presence of acetoacetate in 76% of cases. the urine dipstick result suggested that they were not in ketosis at all (false negative). A false negative rate of 24% to 65% is not good enough for a test used in clinical practice.
Inexpensive and Hassle-Free
One of the biggest benefits of ketone urine strips is that they’re relatively quite inexpensive. Urine test strips come in a small container and don’t require anything other than the strip itself (no fancy add-ons). They are also pretty hassle-free.
Read also: Magnesium Supplements for Keto
Ketone Strips for Diabetics
Ketones are measured primarily by people on a ketogenic (keto) diet. They can also be used by diabetic individuals. For individuals with diabetes, ketones in the urine or blood are a bad thing. Individuals with type-1 diabetes also need to track the levels of ketone in their blood, for medical purposes. It's recommended that diabetics do not use urine strips for this purpose, though.
Diabetic Ketoacidosis (DKA)
If you have diabetes, you can develop diabetic ketoacidosis (DKA), which can be life-threatening. This is more common with Type 1 diabetes but can occur with Type 2 diabetes, as well. Symptoms include high ketones in urine, increased thirst, increased urination, high blood sugar, nausea, fruity breath, difficulty concentration, and tiredness.
For type-1 diabetics, high levels of ketones in your blood can indicate dangerously high blood-sugar levels. Test for ketones if you are worried your blood sugar may be dangerously high.
Prescription Medications
Be aware that ketone strips are not 100% accurate. Ketone levels in urine measured at different times during the day (e.g., immediately after waking up vs. Also, certain prescription medications may interfere with the accuracy of the ketone strip results. These include meds used to treat UTIs.
Alternative Testing Methods
Ketones show up not just in your urine but also in your blood and breath.
Blood Ketone Testing
This testing method measures blood ketone levels of beta-hydroxybutyrate (BHB), the most abundant ketone body. However, the downside is that a ketone blood test is more expensive, not to mention more invasive. Blood ketone testing isn’t for you if you’re scared of drawing blood or find it bothersome.
Breath Testing
Measuring ketosis can also be done using a handheld device called a breath meter or analyzer. What does this measure? Like urine testing, breath testing is affordable, though it has the disadvantage of being less accurate.
Lab Testing
Lab testing is the most expensive and highly accurate way to measure ketones in your serum or plasma (from your venous blood sample). As a keto dieter, this ketone monitoring method isn’t practical because you can’t go to a lab or doctor’s office every day.