When to Test Your Ketones (and Your Glucose)

If you want to know if you are in ketosis or what level of ketosis you are in, you need to test. Testing is the only way to know. And while there are various methods of testing, blood ketone monitors, such as your Keto-Mojo meter, are the most accurate, affordable, and accessible ways for you to test if you are in ketosis, what level of ketosis you are in, and what your blood glucose level is*. So, you have the exact tool you need to give you important insight on what your body is up to! But when is the best time to test?

*Glucose testing, or blood-sugar testing, is commonly conducted to help with diabetes management, but it’s also useful for ketonians because it can reveal “trigger foods,” or foods that spike your glucose and thus may adversely affect your ketone levels.

Let's start here: The very best time to test is when it is convenient for you, especially since consistency is important for tracking your progress. If you choose a time that's convenient for you to test daily, you'll be more likely to continue testing on time, and thus be able to compare your results to prior days at the same time.

As we mentioned, there’s no perfect time to test. However, since sleep and meals can skew test results, certain times are better than others. Here’s when we like to test:

Testing an hour after waking (before drinking or eating).
Testing before you ingest anything but after you’ve been awake awhile helps you avoid the "dawn effect" (an early-morning increase in blood sugar/glucose; in the morning, glucose will be higher and ketones are generally at their lowest; you can learn more about this here.)

At this post-waking time, test results will give you a good baseline level of ketosis in a fasted state. If your ketones are 1 mmol/L or higher during your anticipated lowest levels of the day, that’s good news; it means you are most likely in a deep state of ketosis!

You can further confirm your ketosis status by testing your glucose and then calculating your Glucose Ketone Index (aka GKI, a calculation that gives insight into overall health and your ketosis status).

Glucose Ketone Index (GKI)
This is the formula for getting your glucose ketone index:

(Your Glucose Reading (mg/dL) ÷ 18) ÷ Your Ketone Reading (mmol/L) = Your Glucose Ketone Index

To get your fasting GKI test results, divide your glucose test results (mg/dL) by 18, then take that number and divide it by your ketone reading (mmol/L). The answer is your Glucose Ketone Index, or GKI.

Once you have your GKI, see where you land within the established four GKI levels:

  • >9 GKI Level: your body is not in a fat-burning state, so you may need to adjust your diet, macros, or give yourself more time if you are new to keto.
  • 6-9 GKI Level: a low level of ketosis that is beneficial for those using keto for weight loss and weight management
  • 3-6 GKI Level: a moderate level of ketosis generally sought after by those with metabolic or endocrine disorders looking for therapeutic benefits from the ketogenic diet
  • < 3 GKI Level: a high level of ketosis generally sought after by those using keto therapeutically for cancer, epilepsy, and other medical conditions.

You can do a GKI test any time of day, but it should be at least 30 minutes after eating. Check out our handy GKI Calculator here.

Testing Before Lunch or Dinner
For the most insightful ketone readings, test four hours after breakfast, just before lunch (our preference), or four hours after lunch, before dinner. It’s important that you test three to four hours after eating because consumption of almost any food, keto-friendly or otherwise, will cause your glucose to go up and your ketone levels to fall a bit. Thus, testing well between meals ensures you get a truer reading of your progress.

Testing Before and After Meals
We know we just recommended you don’t test after you’ve eaten. But there is one reason you may want to: testing just before a meal and then 30 minutes and two hours afterward is a great way to find out how your body responds to the various foods, snacks, and drinks you have consumed. (You can learn more about testing for food sensitivities to here.)

When testing for sensitivities, please note that glucose strips give better indications of food reactions because glucose fluctuates faster than ketones. For example, glucose reaches its peak one hour after eating, while ketones take much longer to generate.

Now, onto the next popular question: How often should I test? 

How Often to Test
When you first embark on a ketogenic diet, we recommend testing often, perhaps twice a day, and also testing for food sensitivities.

But generally speaking, the number of times you test each day depends on what you want to achieve. If you just want to verify that you’re in ketosis and are in a rhythm with your new diet, once a day is adequate. If you want to know your GKI and ketosis levels, you'll want to test twice a day. If you’re turning to the ketogenic diet for therapeutic benefits around medical conditions, you may want to test before each meal to see how your day is going and, if necessary, make adjustments prior to eating to ensure you make the proper choices to maintain your desired levels of ketosis.

After several months of keto living, you should have a good sense of what you need to do to stay in ketosis, so you may not need to test as often. (Although it’s a good idea to check in with yourself periodically, as most of us tend to get a little more lax when we’re not kept in check by test results.) Several months into the lifestyle is also a good time to see if you can add more carbohydrates or protein in your diet and remain in ketosis; you’d do this by trying it out and testing your results.

Mojo On!
One of the best things about testing is that positive results encourage you to keep going. It's fun to see the progress, especially because you can usually see it before you can feel it. Want tips on best practices for using your Keto-Mojo meter? You can get them right here.




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