This comes after a Houston man was arrested for blowing well above the legal limit because of his keto diet
According to this article on Men's Health :
Here’s how that can happen: In ketosis, your liver breaks down fat for fuel, creating acetone as a byproduct. Some of that acetone is then released through your breath as isopropyl alcohol. The question is, can breathalyzers tell the difference between ethanol alcohol and isopropyl alcohol? It depends.
SOURCE: Men's Health