One of the common side effects of starting a ketogenic diet is keto breath. Although it’s temporary, having it can make a person feel embarrassed, especially in social situations.
The good news is that you can get rid of keto breath with a few helpful tips. Read on to learn what keto breath smells like, related symptoms, and why it happens in the first place.
What is Keto Breath?
Keto breath, also called ketosis breath, is an unwanted side effect of reducing carbohydrates in your diet. While keto breath is often associated with the ketogenic diet, it occurs on any diet that involves cutting carbs, such as the zero-carb carnivore diet, Atkins diet, and low-carb Paleo diet.
Some people may view keto breath in a bad light similar to ordinary halitosis, but it’s a sign that the keto diet is working to your advantage — more specifically, it means that your body is burning fat for energy (*).
Important: Note that for individuals with poorly managed type 1 or type 2 diabetes, keto breath can be a sign of very high ketone levels, and this increases their risk of ketoacidosis. Along with dangerously high ketones, these individuals also have high blood sugar levels (*).
What Does Keto Breath Smell Like?
You’ll notice your breath smelling fruity or like nail polish remover. This indicates the presence of acetone, which is one of the ketone bodies produced by your liver from fat breakdown. According to William Kemper, owner of Kemper DMD, breathing on your palms can be a reliable way to identify this distinctive “ketosis” odor, which is reminiscent of an extremely sweet or ripe piece of fruit.
Other Symptoms of Keto Breath
Along with this fruity or acetone-like smell, you may notice that your mouth tastes metallic. Kathleen Navarro, RDH, DMD, and consultant for Mom Loves Best, notes that people may also experience dry mouth. When your mouth feels dry, you can also feel thirsty.
Causes of Keto Breath
Your body undergoes a series of changes when you restrict carbohydrates. Knowing what these changes are helps you to understand the mechanism behind keto breath.
Drastic carb reduction leads to the depletion of your glycogen levels. (Glycogen is made up of glucose molecules coming from carb-containing foods.) When this happens, you start breaking down fatty acids, which then get converted to ketone bodies (*). One of these ketones is acetone and it exits your body via your breath. This is why people who are in nutritional ketosis have sweet-smelling acetone-like breath (*).
You may not like this acetone odor, but it’s an important indicator of ketosis, which is a good thing for people whose goal is to lose weight and improve health through low-carb.
How Long Does Keto Breath Last?
Keto breath starts within a few days of doing the keto diet. Nutritional ketosis usually takes place 3 days after reducing carbs, so you may expect to notice keto breath on or after day 3 of keto.
Faith Alex, a practicing medical doctor at National TASC, mentions that keto breath should go away after you’ve been on the keto diet for a few weeks.
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As long as you continue reducing carbs and maintaining a high fat intake, your body successfully adapts to your new diet. Keto adaptation (also called fat-adaptation) occurs at least 4 weeks or a month after reaching and maintaining ketosis. As your fat-burning state continues, keto breath subsides.
How to Get Rid of Keto Breath
There’s no need to quit a keto diet and revert to your old carb habits. Thankfully, there are natural remedies that mask keto breath smell. Check out these tips:
1. Follow a good oral hygiene routine.
Daily habits like brushing your teeth twice daily and flossing between your teeth once daily help to reduce bad breath (*). You may consider using mouthwash as well, however, be sure to choose mouthwash that’s sugar-free.
If you’re scheduled for a dental checkup, this would also be a good opportunity to check for other dental causes of bad smelling breath, such as cavities. While totally unrelated to ketosis, this is part of your overall oral hygiene and shouldn’t be neglected.
2. Chew sugar-free gum.
Sugar-free gum can help mask your breath without adding too many calories in your diet. For example, while regular gum contains 10 calories per serving, a sugar-free version would have only 5 calories and less than 2 grams of carbs (* , *).
Chewing gum while your body tries to adapt to a low-carb diet will help reduce feelings of hunger. In one randomized crossover study, the researchers found that fasting ratings of hunger were lower in subjects that chewed sugar-free gum (*).
3. Keep yourself hydrated throughout the day.
Another method to reduce ketones smell on breath is by drinking more water. Extra hydration allows your body to flush out ketones via your urine.
Just keep in mind to avoid overhydration. Chugging water all the time can throw off your electrolyte levels. This can result in low sodium levels, which can lead to headaches and loss of energy (*).
4. Try lowering your protein intake.
When you’re consuming high amounts of protein at the start of your keto journey, bad breath can occur. Protein is made up of amino acids and excess amino acids produce ammonia, which is exhaled through your breath (*).
You can slightly decrease your protein intake and focus on consuming more fat. This should help in minimizing ammonia production (which smells unpleasant) while also supporting your body through fat-adaptation.
5. Gargle with lemon essential oil or sip lemon water.
Lemon has anti-bacterial properties that can get rid of smelly breath. Study shows that volatile sulfur compound (VSC) production, which cause halitosis, is significantly inhibited by lemon essential oil (*).
Make lemon mouthwash by adding three drops of lemon essential oil to water and swish the mixture around in your mouth for 30 seconds. Alternatively, you may sip lemon water throughout the day. Place a thinly sliced lemon in a bottle and fill it with room-temperature water.
6. Stay committed to your low-carb diet.
The real key to overcoming keto breath is by sticking to the keto diet. Keto breath is only temporary and should be gone by the time your body adjusts to this way of eating, which may happen within a month.
Like with staying on any diet, you can do the same for keto by clearing out carb-rich and sugary foods from your fridge, planning your keto meals in advance, and keeping healthy snacks on hand. And perhaps it’ll help to keep in mind that keto is more of a lifestyle than a short-term fix!
Keto Breath FAQs
Here are common questions and answers pertaining to keto and bad breath:
Can keto breath be prevented?
Yes. A simple way to combat it is by brushing your teeth regularly and flossing. This is part of good oral hygiene, which works by reducing odor coming from food particles stuck between your teeth.
Can keto breath affect my appetite?
Your appetite lowers while in nutritional ketosis, but it’s not because of keto breath (a side effect of keto). Rather, reduced appetite and hunger results from increased ketone levels and your body becoming more effective in burning stored fat.
Can keto breath affect your oral health?
“Because the keto diet is a low-carb diet, it helps reduce plaque build-up and tooth decay,” said Dr. Alex. Sugar coming from carb-rich foods (pastries, potatoes, etc.) can attract harmful bacteria that feed on it and start the process of plaque formation.
Does keto breath go away?
Keto breath may cause you to feel uncomfortable talking to others, but know that it’s only temporary. It eventually subsides as you adjust to your new keto diet which takes up to a month or more. To reach that metabolic adjustment, continue restricting carbs and increasing your fat intake.
Does your breath smell when losing weight?
Weight loss contributes to bad breath if you are depleting your glycogen stores, causing you to metabolize fat. Fat metabolism results in ketones and one of these ketones, called acetone, exits your breath. Acetone breath smells like nail polish or fruit.
The Bottom Line
Low-carbohydrate diets, such as keto, can lead to bad breath due to your body burning its stored fat and producing ketones for fuel. Among the three ketones produced in ketosis, acetone is the main culprit that makes your breath smell like nail polish or a ripe piece of fruit.
Generally speaking, you don’t have to worry about keto breath because it eventually goes away. Also, bad breath on keto is harmless, unless you have other conditions unrelated to keto that create bad smelling breath.
Tips like maintaining good oral hygiene, hydrating yourself, chewing sugar-free gym, and sipping lemon water all help in reducing acetone-like breath without increasing your carb intake. Plus, you may experiment with reducing dietary protein and see if it helps.
When your body becomes more effective at using ketones as its energy source, you breathe out fewer ketones. On top of that, you experience the full benefits of keto.
Veloso K et al. Breath acetone is a reliable indicator of ketosis in adults consuming ketogenic meals . 2002 July 1
Melanson K et al. Chewing gum decreases energy intake at lunch following a controlled breakfast. 2017 July 18