BIOSENSE™ Device Getting Started

Understanding the ACEs Unit

If you have tried or researched the BIOSENSE device, you may have noticed that breath ketone test results are reported in units called ACEs.

But what exactly are ACEs?

ACEs are a unit that translates parts per million (ppm) of breath acetone into a blood ketone equivalent.

Published studies and our own clinical research has shown that blood and breath ketones are closely related. While the correspondence is not 1-to-1, knowing your breath acetone concentration does allow us to make educated predictions about your blood ketone levels.

For example, 2 ppm breath acetone corresponds to approximately 0.5 mmol/L in blood ketones. The ACEs unit is approximately equal to 10x the blood ketone equivalent. Sticking with the above example, 0.5 mmol/L in blood corresponds to an ACEs level of 5.

To summarize: 2 ppm breath acetone corresponds to 0.5 mmol/L in blood ketones, which corresponds to 5 ACEs.

It is important to remember that the 10x correspondence may not be observed for all measurements. The precise blood/breath correspondence depends upon the individual and upon several other factors (there is some interesting research to be done here!). For example, blood and breath ketones do not change at the same rate, and this can lead to deviations from the 10x correspondence when comparing blood and breath directly. If you keep these factors in mind, 10x is a good rule of thumb.

The BIOSENSE device and mobile app put your measurement into context by providing a color indicator along with your ACEs reading. The vertical black bar on the device result screen indicates where your measurement falls on the overall spectrum of ketosis.

ACEs unit biosense

The color BLUE indicates low ketones; the color GREEN indicates that you are in ketosis; the colors YELLOW and ORANGE indicate very high ketones. The same color guide appears on the Day view of the BIOSENSE app.

In this way, the BIOSENSE measurement system provides insight at two levels of granularity: first, your ACEs reading tells you your precise ketone level on a scale from 0-40; and second, the corresponding color tells you where you sit on the broader spectrum of ketosis.

ACEs level

In summary, the ACEs unit was created to provide quick and easy feedback about your state of ketosis by translating breath acetone (ppm) into a whole-number blood ketone equivalent. By understanding how your ACEs level changes throughout the day, you will be well equipped to make informed decisions about your diet and lifestyle.



Comments (5)

  1. Samantha Robertson
    March 11, 2020 Reply

    I was wondering, if I wanted to track the effects of certain foods on my Ketone levels, how quickly will the Biosense show a drop? For example, say I test at 12 before dinner and I eat something new that SAYS it’s keto but I’ve never had it before. Turns out it wasn’t, or my body just doesn’t like it. Would my after dinner reading show a drop, or would it not show until the next day?

    • The BIOSENSE™ Team
      March 11, 2020 Reply

      Samantha –
      Thank you for your inquiry about ketone levels. We appreciate your curiosity!
      Generally, it is ideal to test ketones 2-3 hours after eating. Check out our Best Practices article posted today to understand how our device is best used. In addition, try to test right before lunch or dinner and at least 2-3 hours after you’ve eaten or had a drink (other than water).

      Together in health.

  2. Ray Cardillo
    July 11, 2020 Reply

    My wife and I are seeing 5-7 fairly consistently and I only saw 15 once. However, there were a few times that I expected much higher readings after a long fast period and then consumed almost no carbs throughout the day. Is this a device problem or do some people just not enter advanced ketosis as easily?

    • Andrew Moy
      September 3, 2020 Reply

      As a user, I did a liquid fast – soup, juice, water and hit 40 ACEs consistently for the duration of my 2 week fast. I transitioned my re-feeding to low carb/IF, and hit between 4-20 ACES. I think if you’re looking to go beyond 20+ ACEs, you need to be in full fast mode for a minimum of 36 hours before seeing higher levels.

      • Greg
        March 6, 2021 Reply

        I consume less than 20g net carbs per day (strict keto) and fast between 8pm and Noon the next day. I constantly hit at least 15, and not uncommon to be at 20-25. I don’t measure right after eating and if I have a whiskey I don’t measure until the next morning.

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