Ketone Meters FAQ

Am I in ketosis

Frequently asked questions about using a ketone meter to monitor ketosis

How can I test my ketones at home?

There are three options to enable you to test your ketone levels at home. Thte three options are:

  • Blood ketone meter and blood ketone test strips 
  • A breath ketone meter
  • Urine ketone test strips 

What time of day are ketones highest? 

Ketone levels are usually highest first thing in the morning before you have eaten or drunk anything or after an extended fast. For most of us this is first thing in the morning, as we do not generally eat overnight. For night shift workers this will be different as they are eating during the night and not fasting so their highest ketone levels would be on waking after they have had their sleep period. 

Is ketone meter same as glucose meter?

No a ketone meter and a glucose meter are not the same however many meters now are combined glucose and ketone meters which test for both blood glucose levels and blood ketone levels. To test for both glucose and ketones you would need to purchase a combined meter such as the On Call GK meter and also test strips for glucose and test strips for ketones.

How do ketone monitors work?

Ketone monitors work by measuring the ketone levels in your blood or on your breath. To use a blood ketone monitor you will need to take a finger prick blood sample, and then test it using blood ketone test strips and a ketone meter. To get a reading with a breath ketone meter, you simply need to blow for the required length of time into the breath ketone meter to obtain a result. 

Are ketone breath meters accurate?

Breath ketone meters are not as accurate as blood ketone meters. A breath ketone will give you a guide as to whether you are in ketosis, but if accuracy is important to you, and you want to know your exact blood ketone levels then a blood ketone meter is more accurate. 

More information on how to get the best out of a ketone breath meter and how accurate a ketone breath meter is compared to a blood ketone meter here.

How will I know when my body is in ketosis?

If you test using urine ketone test strips or a ketone monitor you will be able to see if you are excreting ketones, and if you are in ketosis.

If you do not have a meter there a some symptoms you may experience that may mean that your body is in ketosis. Because the symptoms are non-specific, it can be difficult to know if you are in ketosis without testing for ketones.

Common symptoms people may experience when their body is in ketosis:

  • Increased urine output. For me this is the surest sign that I am in ketosis. I see a dramatic increase in my overnight urine output and experience rapid water weight loss.
  • Bad breath is a common side effect of being in ketosis
  • Weight loss-it is common to experience rapid weight loss at the start of a ketogenic diet. A large percentage of this may be because you deplete your glycogen stores in the liver once you start on a keto or low carb diet. There is also a significant loss of water weight.
  • Reduced appetite-many people experience a reduction in their appetite on a low carb or ketogenic diet. This may be due to a lowering in insulin levels on low carb diets or it may be that the ketones in the blood act directly to suppress appetite. 
  • Many people starting on low carb diets may experience mild flu like symptoms including headache and feeling generally unwell and tired. These are often the reasons people stop low carb diets. 
  • Insomnia-being in ketosis increase the incidence of insomnia quite dramatically, and you may find you are waking up in the night.

Why are keto urine strips unreliable compared to a ketone meter?

Keto urine strips are less accurate than a blood ketone meter at telling you your ketone levels, as the urine in your bladder shows you what has been happening over the previous hours and not what is actually happening right now. Having said that they are a good indication as to whether you have been in ketosis and for many people are an easier option than using a meter which requires a small blood sample.


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