Measuring Ketones

Blood Glucose & Ketone Meter

Blood Glucose & Ketone Meter

In my previous post, I talked about measuring blood sugar. In this one I’ll talk about measuring ketones: how, when & why?

Ketones are the body’s response to carbohydrate restriction, as the body moves into “fat burning” as its primary source of fuel. These can be measured by yourself at home using over-the-counter devices, obtainable without any prescription from your pharmacy. There are 3 principal methods for measuring ketones: blood, urine & and now also via your breath, a newcomer to the market. So let’s look at all three methods, as well as the various merits and drawbacks of each in turn.


The procedure for this is very similar to measuring your blood glucose, as described here. Indeed, the device shown on the left is a combined blood sugar and ketone measuring device, hence there is no need to purchase separate devices. The only difference for measuring ketones is that you use separate ketone strips rather than blood glucose strips. The only drawback with these is that they are far more expensive than blood glucose strips, coming in at around $3 each when I purchased mine 3 yrs ago. As far as accuracy is concerned, I found them to be very accurate, with readings consistent with other symptoms i.e. high readings during rapid weight loss, lower readings when weight loss plateaued during the weight loss phase (dairy intolerance) and further, lower readings consistent with nutritional ketosis during the “maintenance phase”. The good thing about blood ketone measuring is that they give you an instant picture of your serum ketone levels, unlike urine sticks. As with blood glucose, these can be measured at any time but again, for baseline values and comparison purposes, I recommend fasting levels should be measured.

Urine Sticks

Urine Ketone Sticks

Urine Ketone Sticks

This method involves providing a urine sample into a small container, dipping a stick in it and waiting a few seconds for the tip of the stick to change colour. The deeper the colour, the higher the ketone value, as compared to a colour chart on the side of the container, see left. This a cumbersome method for obvious reasons but it is also highly inaccurate, with results not necessarily matching your current state of ketosis; there is potentially a long delay between urine and current plasma ketone values.


The final method is via your breath. This is relatively new to the market and I’ve only just found out about it. From what I have read so far, it seems quite expensive and I suspect that like urine, it’s not as accurate as readings derived from blood. If you have any experience of these devices, please let me know. I’d be very interested to share your experiences/ results on this blog. For more information on breath ketone devices see Diet Doctor tweet below:


As per the advice on the “Getting Started” page, there is no need to measure ketones at all, SO LONG AS all is going well and you are happily losing weight. However, if your weight stops falling, or even starts to go up again for no explicable reason, then I do suggest you start measuring ketones and proceed as described here. There could be something in your diet that is inflaming you and blocking ketosis e.g. dairy. If you do decide to measure ketones, then I suggest you do it via a blood sample, since this is the most accurate in MY EXPERIENCE. The jury is still out on the breath version..

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