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Why Keto Breath Stinks (And causes readings on some breathalysers)

February 19, 2020

What is Keto Breath?

Keto is the media's favourite new diet, with keto recipes, cooking books and influencers galore. But something that is not so well known is the existence of a phenomenon called keto breath. The process of ketogenesis causes the presence of certain compounds which are not normally found in the breath. The main problem is that these compounds include acetone and isopropyl, causing the odour of cleaning alcohol to be present on the breath.

How it affects breath tests

Because isopropyl is a type of alcohol, it can cause readings with certain breathalyser methods. For example, budget breathalysers which use semiconductor technology cannot tell the difference between isopropyl alcohol and ethanol alcohol (the alcohol found in food and drinks). Smart Start uses a higher quality fuel-cell technology, also used in Police breathalysers. Fuel cell methods are optimised to be ethanol specific, meaning that keto breath won't cause a reading on our interlock devices.

The Takeaway

Those following a keto diet you might find slightly higher readings on handheld personal breathalysers. A fuel-cell breathalyser such as your interlock won't be affected though. If you want to avoid false positives, the best thing you can do is not put any substances in your mouth (except for water) in the 10 minutes prior to a test. No need to change your diet goals!

Fun Fact: Being on a keto diet can also make your urine smell like popcorn.