Do I Need to Test Ketones?

Ketone testing is one of the most popular methods of tracking dietary performance amongst ketogenic dieters. While there are several ways to test ketones, blood ketone testing has emerged as the most popular method because it has demonstrated the most consistency in research so far.

While I do think that testing ketones is great, there is a problem with our current understanding of testing ketones which has sparked this article.

The Problem With Testing Ketones

The biggest problem with testing ketones is that as a community we have decided that the reading on your ketone meter is the end all be all of optimal health. There are a couple big reasons why this line of thinking is flawed.

The first problem is that we do not have a great understanding of blood ketone levels. While some research states that the optimal level of blood ketones is between 1.5-3.0 mmol, the truth is that there is no way to know this for sure. When we are testing blood ketones we are only testing the ketones that are present in our blood not what our body is actually utilizing.

One of the things we have learned is that as people adapt, their blood ketone levels go down because their body has become more efficient at utilizing these ketones and only produces what the body needs. This means that there is less ketones floating around in the blood thus a lower reading on your blood ketone meter. Based on the thought that ketone levels are the most important success factor for keto, this makes most people panic. However, there is no need to panic, the simple fact is if you are fat adapted your readings are going to be different from a beginner and we don’t have a great way to quantify that difference yet.

The second problem with testing ketones is that just because you have high ketone levels does not mean you are healthy. Ketones are produced when we restrict carbohydrates. You can have a diet that is 100% processed dairy, fast food burgers, and keto treats and still be in ketosis, but that doesn’t mean you are healthy.

Should I Not Test Ketones Then?

Many people are now starting to wise up to the fact that ketone levels are not the gold standard of health. But this has led many to think that testing ketones doesn’t matter at all. This is an overcorrection in the other direction. Just because we cannot take these readings as a stand alone evaluation of our health, does not mean that they are not worth tracking.

There is a lot of value to strategic, non obsessive ketone testing. For example, if you are following keto and not experiencing the benefits of ketosis, testing your ketones can be a great way to determine if it is lack of ketone production that is getting in the way. Or maybe you are going to try a new fasting protocol because you want to see if increasing your ketones in the morning will help you feel energized. Testing ketones during this time is a great way to track the response of your body alongside the subjective feelings you are looking to improve.

One the biggest reasons for testing ketones is the glucose ketone index or the GKI. The GKI is a formula that gives you a single number that quantifies the relationship of your blood glucose and blood ketones. The GKI was invented by the famous Dr. Thomas Seyfried, who in a podcast with Dr. Anthony Gustin, said that the GKI is one of the best indicators of mitochondrial health that we have at our disposal (to learn more about the GKI, check out this article).

There are two things to take note of from this.

  1. Testing blood glucose is also very important. More important than just testing ketones

  2. Testing ketones and blood glucose can allow you to assess if you are getting the benefits of improved mitochondrial health from your ketogenic diet.

Mitochondrial health is what determines our risk for chronic disease. If you are following a ketogenic diet, it is likely that you are doing so to avoid chronic disease. Being able to quantify your success through tracking your GKI is a great way to keep you motivated and determine if some changes need to be made to improve your results.


The take home message here is that you should be not obsessive with your ketones levels. They are not the end all be all of health, we don’t fully understand the readings, and they are not the only number you should be looking at when determining how healthy you are.

However, tracking ketone levels overtime will allow you to determine your specific optimal ketone level and be able to determine how your body is reacting to different dietary strategies.

Ketologist Tip:

If you are going to track ketones, it is important to establish a baseline reading. That means testing under very controlled conditions to ensure that your results are not being skewed by other factors. The infographic below demonstrates the conditions you should test under to get the most accurate baseline measure.

When is the best time to test ketones?.jpg

If you are going to be testing ketone levels, I highly recommend using the Keto Mojo meter! Check out my review of their product here and get a discount on your own meter so you can start elf-experimenting today!

Christopher Irvin