Can a Ketogenic Diet Cause a False Positive on a Breathalyzer?

For individuals adhering strictly to a low-carb, high-fat ketogenic diet, blowing into a police breathalyzer can surface an unexpected, terrifying shock: a positive chemical reading when they haven't consumed a single drop. While an online alcohol level calculator can track mathematical inputs, it cannot trace your unique metabolic fuel sources.

The Science of Exhaled Acetone

When your body enters ketosis, it converts fat stores into ketones for pure cellular energy. One byproduct of this metabolic pathway is isopropyl alcohol and acetone, which is expelled through your breath. Older breath testing machines cannot distinguish between ethanol (drinking alcohol) and exhaled acetone, resulting in a false reading. Cross-referencing your intake with an objective alcohol drink calculator can provide an educational estimate to compare against flawed device responses.