Some Californians are on the keto diet in an effort to lose weight or manage diabetes. The keto diet involves following a strict low-carb regimen so that the body will go into ketosis. During ketosis, the body burns fat for fuel in the absence of carbohydrates. While the keto diet is popular, it might also cause people to have false positives on roadside preliminary breath tests when police suspect that the driver is under the influence.
According to an article in Men's Health, people who are on the keto diet emit ketones as isopropyl alcohol in their breath. This form of alcohol does not impair driving ability and is different from the ethanol alcohol that is found in alcoholic drinks. However, PBT machines that are used by police may not be able to differentiate between isopropyl and ethanol alcohol, leading to false positives and potential DUI charges for people who are sober.
People who are on the keto diet and have had a drink or two may see their results pushed over the limit by the combination of the isopropyl alcohol and ethanol alcohol in their breath. People who think that this might happen to them may want to ask the police to take them to the station for a breath test. These machines use gas chromatography and mass spectroscopy to identify molecules in the breath, and they can detect the difference between isopropyl and ethanol alcohol.
People who are facing drunk driving charges and who believe that their PBTs contained false positives because of their low-carb diets might want to talk to criminal defense lawyers. The attorneys may review the evidence against their clients. If they learn that the PBT results were false and are able to show evidence from the breath test, the attorneys might be able to secure dismissals of the charges against their clients.