› low-carb › ketoThe Best Way to Test Ketones – Diet Doctor The LEVL does not have a battery option, so it can only be operated when connected to a wall outlet. LEVL cautions against testing within 60 minutes of the following: Alcohol, breath mints, chewing gum, cough drops, throat lozenges, tobacco and e-cigarettes, lip balm, smoking, mint or green tea, mouthwash, non-sugar sweeteners (e.g., Sorbitol ...