Does your breath smell sharp enough to scorch the nail polish right off your fingers? Your diet might be to blame. According to some very surprised pioneers of the ketogenic diet, also known as the keto diet, the weight loss regimen makes your mouth taste toxic. The taste and smell of nail polish remover was common enough in keto communities to get its own name: keto breath.
If that smell sounds familiar, you’re not alone. And there’s a perfectly rational explanation as to why this is happening to your mouth.
It has to do with ketosis — the “fat-burning” state your body resorts to when you deprive it of carbs. The theory behind the keto diet relies on eliminating most carbohydrates from your diet, forcing the body to resort to fat for fuel. Keto believers think that this will result in weight loss. And for some people short-term, it does. Long-term results are TBD.
But as your body enters a state of ketosis, it starts breaking down fats. (Usually the body prefers to break down sugars for energy, instead.) It transforms these fats into ketones, which include beta hydroxybutyrate, acetoacetate, and acetone.
These chemicals sound scary, but they’re relatively harmless; the body gets rid of them by expelling them through your urine and your exhales. As a result, you may start to smell them on your breath — acetone in particular, according to the American Journal of Clinical Nutrition.
Besides the keto diet, other scenarios that result in ketone production include fasting, starvation, prolonged and intense exercise, alcoholism, and untreated Type 1 diabetes. In the case of Type 1 diabetes, the chemicals are not so harmless; if you get keto breath without trying the diet, you’ll want to get to a doctor right away.
The stench is sometimes referred to as “fruity,” but often described as smelling similar to nail polish remover. Some dieters don’t mind the smell.
But for others, the stink is strong enough to convince them to quit the diet entirely.
Reportedly, the odor fades as your body adjusts. Just keep in mind that chemical breath isn’t the only thing you’re risking when you go keto. There are some other important health effects to consider before you cut out carbs.