The low-carb, high-fat keto diet is winning over health and fitness enthusiasts everywhere with its promises of weight loss, improved energy, and endless cheesy eggs and avocado mash. However, despite the constant stream of picture-perfect omelets and cut midsections on your Instagram feed, the lifestyle is not without its not-so-gram-worthy side effects. Take the phenomenon of ‘keto breath,’ for example.
Yep, keto breath is a real thing. Here’s what’s up with the stench—and how to get rid of it.
What Is Keto Breath?
Not your average bad breath, experts describe keto breath as a distinct metallic taste and vinegary odor in the mouth. Not only is it normal for keto dieters, but it’s incredibly common.
What Causes Keto Breath
“Keto breath is actually a sign that you’re in ketosis—which is when your body starts using fat for energy instead of carbohydrates,” says Dave Asprey, ‘father of biohacking’ and founder and CEO of Bulletproof.
The process of breaking down fats for energy produces compounds called ketones, which we excrete through our breath, urine, and sweat. One specific ketone, acetone (the chemical in nail polish and nail polish remover), is the culprit of the very specific mouth odor, explains Eric Westman, M.D., M.H.S., Director of the Duke University Lifestyle Medicine Clinic and HEALcare Chief Medical Officer. In fact, many people describe keto breath as having a nail polish remover-esque quality.
Rest assured, these ketones are naturally produced in the body, so while the acetone in your breath may smell toxic, it isn’t.
But Wait—What If Your Breath Smells Like Ammonia?
Aside from nail-polish-remover breath, many keto dieters also report breath that smells like Windex. Caused by eating excess protein, consider this ‘fake keto breath.’
“When the body metabolizes protein, it releases ammonia as a byproduct, which we also excrete through our breath,” says Asprey. Hence the Windex-y odor.
Unlike typical keto breath, this breed of smelly breath indicates you’re not doing keto quite right. The typical keto macronutrient breakdown is 75 percent calories from fat, 20 percent protein, and 5 percent carbs, and eating this way will not cause ammonia breath, says Asprey.
Bottom line: Windex breath equals too much ammonia and too much ammonia equals too much protein. In ketosis, your body should not be breaking down excess protein for energy; it should rely on fat.
Ammonia breath is a common issue for keto newbies, who may focus just on cutting out carbs without thinking much about protein. Once you get your macronutrient proportions right, the stink should go away.
What To Do About Keto Breath
If you’re dealing with keto breath, your first task is to identify whether it’s more nail polish-y or Windex-y in nature.
If it smells like ammonia, check that you’re not over-eating protein by using a food tracking app like MyFitnessPal. Log your food throughout the day to confirm how much protein, fats, and carbs you’re actually eating. If you’re above the 20 percent mark on protein, cut back and the stank should subside.
If your breath is the usual acetone scent, don’t worry too much. “Most people find that it disappears once the body adjusts to using fat for fuel—usually within one to two weeks of starting keto,” says Josh Axe, D.N.M., C.N.S., D.C, author of the upcoming book Keto Diet and member of The Vitamin Shoppe Wellness Council. You see, in the first stages of keto, your liver overproduces ketones to compensate for the fact that you’re ‘running out’ of glucose. Once you’re fully transitioned, though, your ketone production evens out, leaving fewer ketones floating around to taint your breath.
In the meantime, Asprey suggests drinking plenty of water. “Hydrate and then hydrate more!” he says. Since you excrete the stinky by-products of ketosis through your breath and urine, a few extra trips to the bathroom might mean that less acetone exits through your mouth. To further mask the smell, Axe recommends adding mint, parsley, or lemon juice to your water.
Of course, your bad breath could be a sign of poor oral care—especially if it’s not notably glass cleaner- or nail polish remover-like in nature. “No matter what eating plan you’re on, you need to brush and floss daily,” reminds Axe.