This is a common question that we get in our practice. You want to know if you are “doing it right”.
There are several different ways to monitor ketone levels. This includes urinary, blood and breath ketones. There are three forms of ketones in your body, and these are evaluated with these different methods.
Urinary ketone strips are the easiest and most cost-effective way to test for ketones. They run around $6-8 for 100 strips. This test evaluates the ketone acetoacetate. You can do this test at home by purchasing ketone strips, or we can check for you when you are in the office. The biggest downfall of this method is that the accuracy declines over time. After 2-6 weeks in ketosis, urinary ketone levels fall as you begin more efficiently using the ketones in your body for fuel. Therefore, you may be in ketosis but have a negative urinary ketone strip. It is most useful to use when you are initiating ketosis.
Blood ketone levels evaluate beta-hydroxybutyrate. This is a more accurate, but more expensive test. It does require a finger prick which can be uncomfortable for people. This test is done with a monitor you can purchase online for anywhere from around $60-$110. The test strips run from $35-$50 for 50 strips.
If you choose to do this form of monitoring, you may check your ketones more often in the beginning. It can be a nice tool to initially tell when you get into ketosis, and to help you monitor which foods may take you out of ketosis. Over time, you may check occasionally to make sure you remain in ketosis. This may differ if you are following a ketogenic diet to help treat a medical condition such as epilepsy which may require closer monitoring. Ketone levels vary throughout the day and many people have higher ketone levels at night. Ketone levels over 0.5 mmol indicate ketosis, though some people may do better when levels are over 1.5 mmol. Most monitors also are able to check blood glucose levels.
Breath ketone levels evaluate for the ketone acetate. This test has been found to correlate closely with blood ketone monitoring, though I have heard some individuals report that they do not feel it is as accurate for them. The main benefits are that it is a one time purchase and no pokes required. The monitors can run $200+.
But do you really need to test ketone levels? No. We find that testing for urinary ketones when starting a ketogenic diet is a great way to make sure you are getting into ketosis, but beyond this, it is not necessary. Some people like having this information and find it helps to keep them on track. For everyone else, you can track your progress based on how you are doing and feeling. Are you losing weight? Do you feel mentally clear? How is your sleep? Are you struggling with food cravings? How is your energy level? You do not need a monitor to tell you if you are “doing it right” if you are making positive steps towards your goals. This is what really matters.