Ketones: Introduction to Testing Ketones

We’ve all had, or been asked the questions, “How do I know when I’m in ketosis? Should I feel different? Should I have increased mental clarity and focus?” While one could give a case-by-case, yes or no type response for these questions, the best way is to simply test them out. The problem is that most of us don’t have 24/7 access to a lab. Due to this issue, we have three possible ways to test ourselves for ketones from home. Namely, urine strips, blood meters, and breath meters.

Urine Test Strips

There are a number of brands of urine strips to choose from if you decide to go this route, and they can be easily obtained at your local drug store or online retailer 

for a relatively inexpensive price–anywhere from $9–$20 for about 100 test strips. While this would seem to be the easiest way, it may not be the best way. Urine strips are coated with a chemical that reacts to the presence of acetoacetate (one type of ketone body). However, urine, by definition, is a waste product. So, while having ketones present in the urine may be a great indication that you are producing them, it could also mean that you are not utilizing them effectively. Also, we tend to see that individuals who have been on the diet for a long period of time, and/or individuals who are leaner, tend to show lighter or trace amounts of ketones on the strips, compared to people starting the diet, or those who are significantly overweight. For this reason, the strip method may be great to know that you are on the right track with your ketogenic diet, but it may not be the best way to know that you are keto-adapted.

Blood Meters

For a more reliable method of measuring ketones, a blood meter may be the way to go. These meters test for BHB(beta-hydroxybutyrate, another ketone body) and have been shown to be reliable in determining its levels in the blood. ^[1] While it may seem to be the more obvious option for the gung-ho keto enthusiast, there is a caveat… the price is significantly higher! While the meter itself only runs around $20–$30, the strips can cost anywhere from $1–$5 per strip. There is also the problem of having to draw blood–though it’s only a finger prick; however, many people won’t want to do this multiple times per day. So, while it may be more reliable, it is not going to be the most feasible option for everyone.

Breath Measurements

Breath analyzers are a relatively new way to test for ketones. These meters are testing for the presence of acetone (a byproduct of the breakdown of ketone bodies) in our exhalation. One study found that using a breath acetonemeter was as reliable as a urine test strip when testing for ketone bodies. ^[2] This has been confirmed by other studies, that have determined breath acetone to be a reliable predictor of plasma ketone levels. ^[3] The benefit of the breath reader is that it will work even after being in ketosis for a long period of time, as opposed to the urine strips. However, the reliability of these devices, as compared with the blood meter, is still not thoroughly tested and, therefore, needs more testing before definitive conclusions can be drawn.

No matter the method, choose a testing method that is convenient for you! Don’t blow the bank on the blood meters and strips all the time, but the occasional check in never hurts. Lastly, don’t rely on the strips to determine if you’re in ketosis. Based on the principles taught on ketogenic.com, and what you’ve now learned, you will become more in tune with your body and know what’s right for you.

When Do I Test Ketones?

This question, while valid, isn’t as simple as “Test at ‘x’ o’clock.” It can depend on what you’ve eaten, which type of test you’re performing, how long you’ve been in ketosis, and why you’re testing. For simplicity’s sake, we’ll answer a few of these.

If you’re an average Joe just beginning keto and looking to see if you’re starting to enter ketosis, you’ll likely be using the urine strips. The best time for you to test would be within the first 30 minutes of waking up & the first time you use the bathroom. This will show the highest ketone readings, as you’ve been building up the waste product overnight. This is the best way to tell if you’ve been eating correctly early on.

For the avid keto folks who have been on the diet for a while, you may be using the blood meter instead. Your testing time, as noted above, depends on why you’re testing. Testing while fasted can be a great way to determine your baseline ketone levels. However, you may find it interesting to see how your body adapts to different foods, or even after training. For this reason, testing blood ketones can bedone throughout the day to provide a nice snapshot of what is currently going on in your body! Keep in mind, however, that movement and exercise can drastically change the dynamics of ketone readings and, thus, may show differences in levels, even with just a mild walk around the house.

It is worth noting that we do not have a clear understanding of what the optimal ketone level is, and it may vary from person to person. For this reason, if you are not interested in testing, you may be able to determine that you are in ketosis from listening to your body and looking for increased energy and mental clarity.