However, if your breath stinks of ketones or ammonia, one of the most possible explanations is a low-carbohydrate diet. Of course, there are other possible reasons as to why you have what’s known as keto breath. Here are all the things you have to know about this particular type of bad breath. Low-Carb Diets and Ketosis One of the main reasons why people develop ketone-like breath is a low-carbohydrate diet.