What's the Deal with Keto Breath?
Sorry, it's not just your imagination—keto does make your breath stink.
At this point, everyone's heard about the purported benefits of the keto diet: There are accounts of major weight loss, people have more energy for crushing fitness goals (albeit, after getting over an initial dip), and it may even help manage issues like diabetes. But what all these keto fanatics aren't talking about while they're uploading their you-have-to-see-it-to-believe-it transformation pics? The more unpleasant side effects of the trendy diet, like—ugh—keto breath.
If you've ever tried the keto diet (or you've been face to face with someone who has), you may have noticed a funky odor. "This icky-smelling breath is caused by a buildup of ketones and is actually an indication that your body is in ketosis," explains Mariana Dineen, R.D., founder of Pretty Nutritious.
So, keto breath is actually a good sign. It means that, by following the super-low-carb parameters of the ketogenic diet (which means getting 75 percent of your daily calories from fat, 20 percent from protein, and just five percent from carbohydrates, says Dineen), your body has switched over from using glucose as a fuel source and is instead breaking down fat stores and converting them to energy in the form of ketones.
Those ketones include beta-hydroxybutyrate, acetoacetate, and acetone, which may be why some people describe keto breath as smelling like nail polish remover, explains Maryann Walsh, R.D., the owner of Walsh Nutrition Consulting. "Acetone is the main component of nail polish remover," says Walsh. Other people may describe keto breath as fruity smelling, or experience a metallic taste in their mouth.
The real reason for this embarrassing side effect? There are only so many ways your system can purge excess ketones. "Your body releases them through urination and respiration, which is what leads to keto breath," says Walsh. (This may be the same mechanism behind keto crotch, but that's a whole other story.)
There's one other issue that might come into play here: Keto requires you to up your protein intake, which can raise ammonia levels in your body, says Walsh. "As the body breaks down protein, it produces amino acids, one of which is ammonia." Guess what ammonia smells like? Urine and chemicals. And, just like acetone, it's excreted through urine (duh) and respiration, so it could contribute to unpleasant breath.
Fortunately, keto breath should be pretty temporary—just like the keto flu, that initial feeling of fatigue, lethargy, and soreness you might experience when you start the diet. "After a few weeks, your body adjusts to this way of eating and your breath should return back to normal," says Dineen.
In the meantime, since exhaling "drugstore nail polish remover" breath on your friends is probably not your goal, there are a few things you can do to neutralize keto breath.
First, make sure you're drinking tons of keto-approved fluids, especially water. Reminder: Your body gets rid of excess ketones through urine. "Not only will water help flush out any bacteria hanging out in the mouth, but it will also help promote adequate hydration and urination to dilute the ketones in the body," says Walsh. Translation: The more you pee, the fewer ketones build up in the body.
You can also try chewing on fresh mint or sugar-free (duh, can't be wasting those limited carbs) peppermint gum. "Brushing or flossing will not get rid of ketosis breath because it's not caused by poor oral hygiene, it's caused by elevated ketones"—although you should absolutely still practice good oral hygiene, for your own sake and that of everyone around you—"but peppermint works pretty well at masking bad breath and giving you a temporarily minty fresh smell."
If you're still cringing every time you exhale, one simple solution is to eat more carbs. Obviously, the whole point of keto is carb restriction, but "upping your carb intake by about five grams may help lower the levels of stinky ketones your body produces," says Dineen. (And remember, carbs aren't bad for you.) To put things in perspective, that's, like, a quarter of a slice of bread. But, hey, if you'd rather breathe pee-breath into your friends' faces, that's cool, too.