What Is the Best Time to Test Blood Ketones? Identify Needs

by Josh | Last Updated:  September 5, 2020
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Whether you are trying to see if your body is in a state of ketosis or you are working to manage your diabetes, there will eventually come a time when you realize that you should be testing your blood ketones.

What is the best time to test blood ketones? The best time is about an hour after waking to bypass the “dawn phenomenon” but prior to eating your first meal for a daily management level. You should aim for about 1 hour post meal time if you are attempting to see how the meal influences your ketone levels.

To put it simply, if you are checking blood ketones for a ketogenic diet, the best time varies depending on need and per person. This means short of what is listed above that there is no exact schedule that you should follow, which might be disappointing to some people.

There are, however, certain times where it can be more beneficial to check your blood ketones than other times. If you are looking for the best place to start, you will want to begin testing simply when it is convenient for you.

There isn’t really a rush to check your blood ketones unless you are diabetic, in which case there are actually certain times that you should check your blood ketones.

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Are Ketones Higher in the Morning or Evening?

Most ketone readings will be lower in the morning right after waking up due to the “Dawn Effect” where your body kicks in the wake up processes which will tend to increase blood sugar readings, hence your body requires less ketones.

In the evening after the last food you eat your readings will increase based much on whether you ate a large amount of fat, the more fat intake the higher the ketone readings will go when no carbohydrates are involved.

Testing Blood Ketones When You Are Diabetic

If you are diabetic, you should partner with your physician and you should test for blood ketones if your blood sugar is over 250 or if you feel ill, and if there are signs of dehydration.

For diabetics, the proper blood ketones levels are also different. For instance, the normal range of blood ketones is going to start at 0.6 mmol/L. Between 0.6 mmol/L and 1.0, mmol/L is considered the range of normal for a diabetic.

Between 1.0 and 1.5 mmol/L means that you should probably call your doctor on advice for what you should do next but it is not quite at a level of pure urgency. Between a level of 1.5 and 3.0 mmol/L, you could be at risk for ketoacidosis.

Keto mojo checking the blood ketone levels by grabbing blood in a lancet from the finger - What Is the Best Time to Test Blood Ketones
A Keto-Mojo checking the blood ketone levels

You should call your doctor immediately if you find yourself in this range as it can be dangerous to your health. If your blood ketones are over 3.0 mmol/L, then this is considered a medical emergency and you should find the nearest emergency room or call 911.

Of course, your doctor should go over this with you and help you understand how to read your blood ketone levels. If you are looking at your blood ketones because you are trying to manage a ketogenic diet, the guidelines are going to be vastly different.

When Should You Test Blood Ketones for a Ketogenic Diet?

The guidelines for testing blood ketones while you are on a ketogenic diet are significantly less strict than they are for diabetics. Generally, you will want to test your blood ketones about an hour after waking up and before you have had anything to eat or drink.

Testing your blood ketones at this time specifically will give you the best idea of what the ketone levels in your body are at when you are in a fasting state.

By avoiding eating for that first hour, you can avoid the phenomenon known as the “dawn effect” that can happen when you increase your blood sugar in the early morning by eating.

When you do this, your glucose will be higher and your ketones will be at their lowest point, which is the exact opposite of what you want when you are on a ketogenic diet.

You could also test your blood ketones before lunch or dinner. You will want to do this four hours after your previous meal. For example, if you are planning to test your ketones before lunch, make sure that breakfast was around four hours ago before you test.

This will ensure that the blood ketone reading isn’t affected by lingering glucose from your last meal.

If you are curious as to how your body responds to your food, you can also go the extra step and measure your blood ketones before and after you eat. You will want to make sure that you are measuring the blood ketones right before you begin eating your meal to get your initial reading.

After that, you will want to test both 30 minutes after the meal and then 120 minutes after the meal. This will give you a good idea of how your body responds to the food that you have ingested.

How Often Should You Test?

As for how often you should be testing, it varies as well. If you are just beginning a ketogenic journey, you might want to test around twice a day as well as test occasionally for food sensitivities.

In the beginning, you will want to test more often so that you can get a good idea of how your body works and how long it takes to achieve a ketogenic state. As you continue with this lifestyle, you will come to learn more, eating properly will become natural, and you will find that you need to test less and less.

If you are diabetic, your doctor will go over if, when, and how often you should test your blood ketones.

Ketone Chart - What Is the Best Time to Test Blood Ketones

What Do the Readings Mean?

If you want to get an even more accurate idea of your ketosis, you can also measure your glucose levels as well and use both your blood ketone level and your glucose level to gauge your Glucose Ketone Index. The formula for this index is the following:

(Your glucose reading (mg/dL) ÷ 18) ÷ Your ketone reading (mmol/L) = Your Glucose Ketone Index

Going by the Glucose Ketone Index (GKI), each reading will have a different meaning. If your GKI level is over nine, then your body simply isn’t in a state where it is burning fat. You should adjust your diet and macros accordingly if you find that you are regularly at this level.

If your GKI is between six and nine, then you are at a low level of ketosis. This is good if you are working to manage weight or lose weight. Below that, if your GKI is between three and six, then you are in a moderate ketosis state.

People who have metabolic or endocrine disorders will often look for this level of ketosis when working with a ketogenic diet. Finally, if your GKI is below three, then you are at a pretty high level of ketosis. People will work to achieve this level therapeutically for cancer, epilepsy, and other medical conditions.

Now that you know what different blood ketone levels mean, you can begin managing your ketogenic diet even further, achieving the results you have always wanted.

Final Thoughts on What is the Best Time to Test Blood Ketones

This has many answers as you can see you really want to test around understanding more about your body and how it reacts to waking up, eating specific foods, after workouts, and more.

If you go hard at the gym and then measure your blood ketones you may see numbers go up to 5+ on a ketone reader as you just asked your body to bring in massive energy needs.

If you had a meal that was keto style low carb and super high fat you will see your readings have gone up, so don’t measure to just measure, you want to measure to a need to understand yourself and your body.

I grew up in a home where most our days were spent inside, and sports were not a family priority. I did play soccer and baseball as a kid, but the older I got, the more I lost interest. To regain my health, I decided to adhere to the three tenets of health and longevity. I hope you will join me, by making it your purpose to live as long and well as possible.