The ketogenic diet is one of the only diets that is actually a physiological state, rather than a diet. You could be on the traditional low-carb/high-fat diet, or even a carnivore diet, as long as your body is producing ketones, you are in ketosis.

There are two main options for home ketone monitoring: blood ketone meters and urine ketone test strips. Let’s explore the pros and cons of each to help you decide which is right for your keto journey.

Blood Ketone Meters: Precision Tracking

Blood ketone meters offer a more precise measurement of blood ketone levels. A small finger prick draws a blood sample that the meter analyzes, providing a real-time ketone level reading. This accuracy allows for:

• Fine-Tuning Your Diet: By tracking how different foods affect your ketones, you can personalize your keto approach to maximize fat burning [1].
  Identifying Ketone Levels for Optimal Performance: Some studies suggest a “sweet spot” for ketone levels for athletic performance or cognitive function, and blood meters can help you target that range [2, 3].

Drawbacks of Blood Ketone Meters

Cost: Blood ketone meters and test strips can be expensive compared to urine test strips.
Invasive: Finger pricking can be uncomfortable or inconvenient for some users.

Limited Snapshot: Blood ketones can fluctuate throughout the day, so a single reading may not represent the whole picture.

Urine Ketone Test Strips: Affordability and Convenience

Urine ketone test strips are a more affordable and user-friendly option for ketone monitoring. You simply dip the strip in your urine stream and compare the color change to a chart to estimate your ketone level.

Limitations of Urine Ketone Test Strips:

• Less Precise: Urine ketone readings are not as accurate as blood readings. They may not detect ketones until your levels are already high, and they can be influenced by hydration levels [4].
  Delayed Response: Urine reflects ketones excreted by the body, so it can take several hours to show changes in your current ketone production.

Science on Blood vs. Urine Ketones

A 2017 study published in the National Institutes of Health’s journal, Nutrition & Metabolism, compared blood and urine ketone measurements in healthy adults. The study concluded that urine strips underestimated blood ketone concentrations, particularly at lower levels [4].

Another study, published in Biosensors and Bioelectronics in 2016, evaluated non-invasive methods for ketone detection, including urine test strips. The authors noted that urine strips can be a helpful tool for initial screening but may not be suitable for precise monitoring [5].

Choosing the Right Tool

The best ketone monitoring method depends on your individual needs and goals.

For a basic understanding of ketosis and general tracking: Urine test strips may be sufficient.
For those seeking more precise data to optimize their keto approach: Blood ketone meters offer a valuable tool.

Continuous Blood Glucose Monitor (CBM) on Keto

While not specifically designed for keto, continuous glucose monitors (CGMs) can offer valuable insights for people on this lifestyle. CGMs provide real-time blood sugar readings throughout the day, allowing you to see precisely how your body reacts to different foods and how effectively it enters ketosis. This granularity can be particularly helpful during the initial adjustment phase of keto, where you’re fine-tuning your diet to achieve optimal ketone levels.

However, it’s important to remember that CGMs are primarily used for diabetes management, and their role in a ketogenic diet is still under investigation.

Personally, I’ve found them useful at the beginning of my keto journey but less so later on. Specifically, it helped me to understand how my body responded to different foods (even small amounts of carrots spiked my sugar for example).  Later in my keto journey, I found continuous blood glucose monitors to be somewhat inaccurate and more of a cause of anxiety than guidance.

Additionally, the cost of CGMs and their consumables can be significant. For most people on keto, urine test strips or blood ketone meters might be a more practical choice. Ultimately, consulting with a healthcare professional familiar with both keto and CGMs can help you decide if it’s the right fit for your goals.

Ultimately, consulting with a healthcare professional or registered dietician familiar with keto can help you determine the best ketone monitoring strategy for your journey.

References

1. Paoletta, M., et al. (2015). Effects of a ketogenic diet on metabolic parameters in overweight subjects with type 2 diabetes. Nutrition & Metabolism, 12(61). https://www.ncbi.nlm.nih.gov/books/NBK499830/
2. Vargas, E., et al. (2020). Nutritional ketosis and exercise performance. Nutrients, 12(11), 3109. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6835497/
3. McSwiney, F. T., et al. (2018). Does dietary ketosis improve cognitive performance? A systematic review of human intervention trials. Nutrients, 10(12), 1834. https://pubmed.ncbi.nlm.nih.gov/36354157/
4. Lim, S., et al. (2017). Comparison of blood and urine ketone measurement methods in healthy adults. Nutrition & Metabolism, 14(1). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5298446/
5. Zhang, D., et al. (2016). Electrochemical sensors for non-invasive detection of ketone bodies. Biosensors and Bioelectronics