Keto Urine Strips: How Do They Work?

Ketone test strips are a convenient way to test for ketosis. They are thin paper or plastic strips with a small reactive pad at one end that changes colour when it comes in contact with ketones in the urine. The strips are easy to use and provide results in under a minute. However, they are not always accurate, especially for people with kidney problems, and may not be reliable for those who are fat-adapted.

How to use keto urine strips

Keto urine strips are a convenient and affordable way to test for ketones in your urine. They are especially useful for people on a ketogenic diet who want to check if they are in ketosis. Here is a step-by-step guide on how to use them:

Step 1: Wash your hands

It is important to maintain good hygiene when handling urine keto strips. Make sure to wash your hands before and after the test.

Step 2: Collect a urine sample

You can either urinate directly into a small, clean container or aim directly at the strip as it takes only a few seconds of exposure for the strip to absorb the required amount of urine.

Step 3: Dip the strip into the urine sample or pass it through the urine stream

If you have collected a urine sample in a container, dip the test end of the strip into it. Alternatively, you can pass the end of the strip through your urine stream as you urinate.

Step 4: Wait for the strip to change colour

This usually takes a few seconds to a minute. The strip has an absorptive pad that contains a chemical reagent that reacts with the ketones in your urine and changes colour. The deeper the colour, the higher the level of ketones in your urine.

Step 5: Compare the colour with the colour chart

Each pack of keto urine strips comes with a colour chart that indicates the level of ketones in your urine based on the colour of the strip. Match the colour on your strip to the one on the chart to determine your ketone level.

Step 6: Dispose of the strip and wash your hands

Do not forget to throw away the strip after use and wash your hands to maintain good hygiene.

Additional tips:

• Find the best time to use the strips: According to a study, the early morning or after dinner are the times of the day with the highest and most reliably detectable levels of ketones.
• Test different methods: Some users report different results when urinating directly on the strip versus using a urine sample. Experiment to see what works best for you and your brand of strips.
• Store the strips properly: Keep the strips away from strong light and moisture, and don't forget to replace the cap and leave the desiccants inside after taking out a strip.
• Check expiration dates: Urine test strips usually expire within 3-6 months after opening, so make sure to use them before the expiration date for accurate results.

How accurate are keto urine strips?

Keto urine strips are a good tool to measure whether you’re in ketosis during the first few weeks of starting a keto diet. They are designed to monitor diabetic ketones to help prevent diabetics from getting into ketoacidosis, a dangerous metabolic state caused by insulin deficiency.

However, urine strips are not always accurate. They are inaccurate in determining nutritional ketosis and how well your body is utilizing ketones as fuel. This is because urine strips measure excess or excreted ketones in the urine. When transitioning to ketosis, the body will make excess acetoacetate ketones, which will show up in your urine and on urine strip tests. However, as your body becomes fat-adapted, it converts ketone bodies more efficiently and is less likely to expel them. Therefore, if you’ve been in a keto-adapted state for many months, a keto urine strip may indicate that your urine contains only trace amounts of ketones, if any, which can mislead people into thinking they’re no longer in ketosis.

The accuracy of urine strips is also affected by your level of hydration, with varying levels of hydration resulting in inconsistent results. In addition, the readings are somewhat subjective when comparing the colour on the strip to the colour on the package. The reading you get is also not a reading at the moment in time, but the sum of ketones present since your last urination.

Therefore, urine strips are a great way to know that you are starting to produce ketones in your first few weeks of following a ketogenic diet but are not an accurate measurement of nutritional ketosis. If you plan to follow a ketogenic diet for more than a few weeks, it is recommended to invest in a blood ketone and glucose meter, which will allow you to more accurately measure your level of ketosis.

What do keto urine strip results mean?

Ketone test strips are made from a type of paper that changes colour when it reacts with your urine. They measure acetoacetate (AcAc), the second most abundant ketone that your body excretes through urine. Urine testing is non-invasive and the most convenient ketosis testing method that provides results in seconds.

How to interpret keto urine strip results

Keto urine test strips have a light beige colour, which darkens with high levels of ketones. The deeper the colour, the more ketone bodies are detected in your urine.

• Negative (no ketones): You are not in ketosis at all
• Trace (0.5 mmol/L): This means light nutritional ketosis
• Small (1.5 mmol/L): This means light nutritional ketosis
• Moderate (4.0 mmol/L): Ketones increase further as a result of exercise or fasting
• Large (8.0 mmol/L): Usually a result of prolonged fasting, not sustainable in the long term
• Larger (16 mmol/L): Usually a result of prolonged fasting, not sustainable in the long term

Note: mmol/L stands for millimoles per litre, and it refers to the concentration of ketones in a specific amount of liquid — in this case, your urine.

The optimum level for ketosis falls between 0.5 and 2 mmol/L due to following a well-formulated ketogenic diet.

Other factors that affect urine ketone test results

In some cases, your ketone levels may decrease or increase despite your consistency with your keto diet. Here are a couple of reasons why this occurs:

• Adaptation: As you maintain a ketogenic lifestyle, your body adapts and becomes more effective in utilising ketones as its fuel source. This means that ketones are less likely to spill over into your urine. You might actually be at a deeper level of ketosis, but it doesn't show in your test results.
• Dehydration: One randomised controlled trial found a direct proportion between serum ketone concentration and the level of dehydration. The more dehydrated a subject was, the higher their ketone levels. Ensuring good hydration when testing for ketones helps produce more accurate and consistent results.
• 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. Store the bottle in a cool, dark place, away from direct sunlight to preserve their quality.

When is the best time to use keto urine strips?

The best time to use keto urine strips is early in the morning on an empty stomach. This is because your body will have rested and cleared the food taken in before night, giving you accurate results. You can also test at other times of the day, such as before lunch or dinner, but you may want to ask your doctor if any medications you are on may interfere with the test.

When you first start the ketogenic diet, it is recommended to test often, perhaps twice a day, to monitor your progress and watch your progression into ketosis.

How do keto urine strips work?

Ketone test strips are made from a type of paper that changes colour when it reacts with urine. They measure acetoacetate, the second most abundant ketone that the body excretes through urine.

The strips have an absorptive pad on one end that contains a chemical reagent (usually nitroprusside) that changes colour in the presence of acids such as ketones in urine. The colour change varies depending on the concentration of ketones. Light pink means ketones are present but in small amounts, while dark purple means you're in full-blown ketosis.

Here's how to use them:

• Wash your hands.
• Pee into a small, clean container, then dip the test end of the strip into the urine sample. Alternatively, pass the end of the strip through your urine stream.
• Wait a few seconds (or as indicated on the test package) for the end of the strip to change colour.
• Compare the colour with the colour chart on the test package.
• Dispose of the urine testing strip, then wash your hands.

However, it's important to note that ketone strips are not always accurate. They are most accurate when used early in your keto diet. They may not be accurate if you are fat-adapted, as your body may be using up all the ketones efficiently, so none go to waste through urine.

Frequently asked questions