Why Your Low-Carb Diet Is Giving You Ketosis Breath

Understanding the Causes and Treatment Options

Bad breath is one of the possible side effects of a low-carb diet, such as the Atkins Diet or South Beach Diet. Known as ketosis breath, or simply keto breath, the condition is often accompanied by a foul taste in the mouth. Symptoms like these can be distressing, but, fortunately, there are things you can do to overcome them without undermining the goals of your diet.

Causes

There are many causes of bad breath, but, with regards to low-carb diets, there are two primary mechanisms: ketosis (the metabolic state achieved with a low-carb diet) and protein metabolism.

Ketosis

One of the body's primary sources of energy is glucose. Glucose is created when the digestive tract breaks down carbohydrates, in the form of complex sugars, into simple glucose molecules. With a low-carb diet, the reduction of carb intake means that your body has to find alternative fuel sources, namely fat, for energy. This state of metabolism is known as ketosis.

As the body breaks down fatty acids, it creates a byproduct known as ketones. Ketone bodies come in three common forms known as acetoacetate, beta-hydroxybutyrate, and acetone. These bodies are typically removed from the body when you urinate or exhale.

With a low-carb diet, the excessive accumulation of ketones can contribute to bad breath. Moreover, the quantity or balance of the ketones you exhale can create very different and distinctive smells, most of which are unlike what you would experience with halitosis ("everyday" bad breath).

Protein Metabolism

Changes in your diet can also trigger changes in your breath. With a low-carb diet, the sudden switch from carbs to proteins will alter how your body metabolizes the foods you eat.

When protein is broken down by the body, it creates ammonia. The sudden surge in protein will only amplify this effect, not only increasing the amount of ammonia in your stomach gases but in your urine as well.

Because it takes a lot of water to excrete ammonia, inadequate hydration can lead to a worsening of your bad breath as ammonia rapidly accumulates in the body.

Symptoms

Keto breath can vary from person to person but tends to differ from halitosis. With halitosis, mouth bacteria is the common culprit. As the bacteria break down food, they create volatile sulfur compounds (VSCs) that exude sulfurous odors, not unlike that of rotten eggs.

With keto breath, the characteristics of the smells can vary based on the various byproducts of protein or fat metabolism. For example:

  • Acetoacetate and beta-hydroxybutyrate can cause your breath to smell sweet and fruity. Some people describe the odor as bruised or rotting apples.
  • Acetone on the breath creates more of a resiny smell, not unlike that of nail polish.
  • Excess protein metabolism may not only cause you to have ammonia breath but may also make your urine smell of ammonia.

Treatment

The good news is that keto breath usually doesn't last forever. In most cases, it disappears within several weeks to a month. If you are on a low-carb diet and are on the fast track to weight loss, you will likely want to stick with the program and find ways to mitigate the symptoms of keto breath. Here are some tips that can help:

  • Drink more water. Aim for no less than eight 8-ounce glasses of water per day, more if you are heavier. This not only helps flush excess ketones and VSC from your body, but it also aids in digestion and prevents constipation.
  • Change the balance of proteins you consume. This is a trial-and-error process in which a change of protein sources—say, from chicken to meat or meat to fish—can sometimes alter which ketone bodies are being produced (mainly by the types of fatty acids begin broken down).

Research suggests that increasing fat intake while reducing protein consumption can help minimize both acetone and ammonia emissions.

  • Don't undercut the carbs. While you will want to keep to your diet plan, don't be overzealous and cut out more carbs than you need. The South Beach Diet, for example, is not as strict on the carb count as the Atkins Diet; neither, however, aims for a zero-carbs policy. So if you're going overboard on carb avoidance, back away and increase your intake within the prescribed limit.
  • Mask your breath. You can natural breath fresheners (such as mint, parsley, cloves, cinnamon, or fennel seeds) or breath capsules made from parsley oil or chlorophyll.

Sugar-free mints and gums made with xylitol can help mask bad breath while exerting mild antibacterial properties to control VSC.

  • Practice good oral hygiene. Brush your teeth, floss, and rinse with an antibacterial mouthwash. VSCs are also produced during protein metabolism and may add to your bad breath problem if you don't maintain proper oral hygiene. Regular tongue scraping can also help.

A Word From Verywell

If your bad breath persists for more than a couple of months despite best efforts, speak with your doctor or dentist. In some cases, the bad breath may have nothing to do with your low-carb diet but rather be related to dry mouth, gum disease, or medical conditions such as acid reflux, diabetes, sinus problems, or liver or kidney disease.

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