Alcohol is byproduct of normal metabolism. At the moment the Atkins diet, consisting of high protein content but no carbohydrate, and popularised by various Hollywood celebs including Jennifer Aniston, is very popular. If you remain on this diet for a long time you produce a higher amount of ketone bodies which result in smelly breath and the possibility that you may test positive on a breath test. If you have certain undiagnosed medical conditions you may test positive. I will investigate these further tomorrow since my degree was a while ago, but tonight will drink wine because I will not have the opportunity for another 2 weeks.