How "ketosis" can produced a falsely high BAC reading
Some medical conditions and diets that involve a low intake of carbohydrates can cause Nevada DUI breath tests to produce falsely high results. These include:
- Anorexia nervosa ("anorexia"),
- Fasting, and
- High-protein / low-carbohydrate diets (such as the Atkins, Zone, South Beach and Paleo diets).
These diets often involve insufficient carbohydrate intake for energy, resulting in the body "burning" fat stores instead. An unintended side-effect of using fat for energy, however, is the production of waste products known as "ketones.”
Ketones are similar in chemical composition to isopropyl alcohol, which is found in solvents such as acetone.1 Isopropyl alcohol is different from ethyl alcohol, the type of alcohol in an alcoholic beverage.
Nevada DUI breath testing devices cannot, however, always reliably distinguish isopropyl from ethyl alcohol. Worse, “ketosis” can produce visible signs that mimic alcohol impairment, including:
- Dehydration and excessive thirst,
- Flushed face,
- Decreased coordination, and even
- Breath that smells like an alcoholic beverage.
As a result, if you are pulled over for a traffic stop when your body is undergoing ketosis, a Nevada law enforcement officer may think you are drunk. Worse, a Nevada DUI breath testing device might confirm the officer's suspicions by showing a high blood alcohol concentration (BAC) -- even if you have had nothing to drink or not enough to make you drunk.3
To help you better understand how your diet might lead to a falsely high reading on a Nevada DUI breath test, our Las Vegas, Nevada DUI defense lawyers discuss the following, below:
- 1. What are ketones?
- 2. How low-carbohydrate diets and fasting cause ketosis
- 3. How ketones “trick” DUI breath testing devices
- 4. Low-carb diet or fasting as a Nevada DUI defense
Our bodies derive most of our energy from carbohydrates in our diet. When we eat foods containing carbohydrates, our digestive system breaks them down into various sugars. These include glucose, which is the body's main energy source. After eating, glucose is absorbed into the bloodstream, which is why it's often referred to as “blood sugar.”4
If, however, we don't consume enough carbohydrates to produce the glucose our bodies need, our bodies will burn our stored fat instead.5 While this is obviously useful for dieting, it can create problems if we are stopped for DUI.
Fats are broken down in the liver. Our liver turns fat into energy we can use. But in the process, it also creates waste products, known as ketones.6 Chemically, ketones are similar to isopropyl alcohol (acetone). And not all breath testing devices can reliably distinguish isopropyl alcohol from ethyl alcohol, the kind of alcohol found in alcohol beverages.
“Ketosis” is normal during fasting, after prolonged exercise, and when a high-fat diet is consumed. Excess ketosis, however, can create all kinds of problems, including symptoms such as dizziness, confusion and alcoholic-smelling breath that can make you appear drunk.
Ketosis results most frequently when there is insufficient carbohydrate intake. In addition to fasting, causes of inadequate carb intake include (without limitation):
- High protein / low carbohydrates diets (such as the Paleo or Atkins diet),
- Excessive vomiting,
- Excessive diarrhea, or
Much like alcohol, excess ketones are excreted in the urine and breath. But because Nevada DUI breath testing devices are not sophisticated enough to distinguish reliably between isopropyl and ethyl alcohol, ketones in the breath can register as alcohol.7
As a result, when you are fasting or on a high-protein diet, you can test “positive” on a Nevada DUI breath test even when you haven't been drinking or have consumed only a small amount of alcohol.
If you are on a diet – or if you suffer from any medical condition -- it is important to discuss it with your Nevada DUI defense attorney. With the help of an expert witness, an experienced Las Vegas or Reno DUI attorney may be able to convince the prosecutor that you weren't drunk when you drove. This can lead to the reduction of your Nevada DUI to reckless driving, a reduction of your Nevada DUI to careless driving, or even an outright dismissal of your case.
And if your case does go to trial, the fact that you were dieting might just create reasonable doubt of your guilt in the jury's minds. As Las Vegas DUI lawyer Michael Becker explains:
"Medical conditions and Atkins-style diets are so effective at mimicking DUI it can be hard to convince an officer you weren't drunk. An experienced Nevada DUI defense attorney can make sure the D.A. understands how your diet might have produced a falsely high BAC on your Nevada DUI breath test.”
Charged with DUI in Reno or Las Vegas? Call us for help…
If you were accused of DUI and think that your diet or medical condition might be the culprit, we invite you to contact us for a free consultation.
Our caring DUI defense lawyers defend clients throughout the state of Nevada on drunk driving and DUI of drugs charges.
To speak for free to one of our lawyers, call us at 702-DEFENSE (702-333-3673). Or fill out on the form on this page and someone will promptly return your inquiry.
To learn about ketosis as a drunk driving defense in California, please see our article: How Low-Carb / High-Protein Diets Can "Trick" a California DUI Breath Test.
- Jeanette Allen Behre, Studies in Ketone Body Excretion, Journal of Biological Chemistry, June 25, 1931, J. Biol. Chem. 1931, 92:679-697.
- Alice and Fred Ottoboni, Ketosis, Ketone Bodies, and Ketoacidosis: Modern Nutritional Diseases, 2nd Edition, Chapter 8 (Lipids), February 20th, 2013 (“Excess ketone bodies are excreted by the kidneys and lungs. Exhaled acetone gives the breath a characteristic, sweetish odor.”).
- The American Association for Justice, Challenging the DUI Breath Test: Breath Testing Basics and Factors Affecting the Test.
- Harvard School of Public Health, Carbohydrates and Blood Sugar.
- WebMD, Diabetes Health Center: Ketones.
- University of San Francisco, What are ketones and why do I need to know about them?
- Lawrence Taylor, Drunk Driving Defense 3d Edition, page 685. ("...the likelihood exists of auto-generated isopropyl alcohol upon the introduction of carbohydrates in the presence of ketosis and that the Intoxilyzer [Nevada DUI breath testing instrument] cannot dependably distinguish ethanol from isopropyl alcohol.")