If you were to ask someone to describe their experience with the ketogenic diet to you, almost everyone would start singing praises for this currently trending meal plan, saying how they were able to shed a lot of weight while still enjoying “unhealthy” foods like cheese, red meat, butter, etc. What they may avoid mentioning is the dreadful keto breath smell that affects many low carb dieters, especially during the first few weeks of this and other very low carbohydrate diets. While this side effect is not necessarily experienced by everyone on the keto diet, if you are considering going on this meal plan it is best to understand the causes, symptoms, longevity, as well as the available remedies of this phenomenon – just in case.
What Is Keto Breath And What Are Its Symptoms?
As previously mentioned, keto breath is one of the side effects that comes from being on a very low carb meal plan such as the ketogenic diet. Unlike morning breath or just typical bad breath, keto breath is said to not only be distinctly unpleasant but it can also leave your mouth with an odd taste.
In terms of the ketogenic diet bad breath symptoms, you are likely to experience
- A funny metallic taste in your mouth
- Fruity breath – This goes one of two ways, it could either be a sweet smell or more often, something described as being similar to the smell of rotting apples
- Nail polish remover – Some people report smelling acetone on their breath
Why Does Keto Make Your Breath Smell?
To properly understand the causes of keto breath smell we must first understand some things first. When you switch your eating habit to the ketogenic diet, the goal is to entirely change how your body’s metabolism works. Here’s how:
Ordinarily our bodies use the carbohydrates that we consume as the main energy source to keep us going. On a balanced diet that includes carbohydrates, protein, and fats, the body will first break down the carbs, turn them into glucose and use this as fuel. Once the glucose is gone and there are no more carbs to burn, it will then turn to breaking down fat and using that as the energy source.
As we all know by now, keto is a very low carb diet that requires those following it to highly restrict their carbohydrate intake. Keto diet followers can only ingest five to 10 percent of their total daily calorie intake as carbs – which equates to anywhere between 20 to 50 grams of carbohydrates a day on a 2000 calories meal plan (4).
This extreme restriction of carbohydrates changes how your metabolism works. Because the body no longer has carbs to turn into glucose and use that as energy, it is forced to now burn and break down fat for energy. This process puts your body into ketosis – a metabolic state in which ketones (chemicals the body produces when it breaks down fat for energy) become an important source of energy for the body and brain.
So how does this cause a keto metallic taste and bad breath?
It’s important to note three main facts:
- Our bodies naturally produce ketones in the liver when we do not have enough glucose to use as energy.
- Ketones (or ketone bodies) come in three types namely beta hydroxybutyrate, acetoacetate, and acetone (6).
- Any ketone bodies that may be left over after the body is done with them are usually released either through your breath or through your pee because the body cannot tolerate large amounts of them.
Excess ketones can cause a chemical balance of your blood which if left untreated can poison the body – your blood becomes too acid leading to a serious life threatening condition known as ketoacidosis (2). Hyperketonemia, a condition where one has elevated blood levels of acetoacetate (AA), 3-β-hydroxybutyrate (BHB), and acetone is also another side effect of excess ketones (3).
With this in mind, we now understand that when your body is constantly in ketosis, you end up having large amounts of ketones in your system. While the body may use some of them as energy, it cannot possibly use up all of them because thanks to your diet you are always producing more and more of them.
To regulate these ketones, your body will have to get rid of them which as mentioned above happens mainly through your breath and urination. The culprit behind your bad breath comes from these chemicals, mainly acetone (1) – one of the types of ketones as well as the main ingredient in nail polish remover.
How To Get Rid Of Bad Keto Breath Smell
While keto breath is a very obvious indicator that your body is now actively in ketosis and burning fat for energy, it can also be very debilitating to your life, especially your social life. So ways to manage and get rid of this bad breath include:
- Drinking more water – As mentioned above, your body gets rid of excess ketones through your urine and your breath. Drinking more water not only keeps you hydrated, it also helps you pee more which allows more ketones to be flushed through urination rather than through your breath.
- Invest in some breath mints and other breath fresheners – This may not get rid of the bad breath, but it helps mask it for a while allowing you to interact with others without feeling self conscious.
- Brush your teeth more – This works the same way as breath mints by masking the smell for a while. Be sure not to overdo it as over brushing will lead to sensitive gums and receding gums. If you are not around people, eat some mints and drink more water.
- Increase your carbohydrate intake – Yes, the goal of a ketogenic diet is to eat as little carbs as possible. While this may help with faster weight loss, it also means that your body is overloaded with ketones.
By increasing your carb intake, you not only reduce your daily caloric fat intake but you also give your body carbs to make glucose, thus it doesn’t need to make as many ketones. Just try to stay under the 50 grams cut off point so you can still be in ketosis and eventually reach your body goals.
- Be patient – Bad keto breath is not forever, just give it time and it may go away on its own.
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What Is Keto Body Odor?
Keto body odor is basically the same as keto breath – only this time, instead of the smell coming out of your mouth, it exits your body through your sweat glands which leads to you having incredibly bad body odor.
What Does Keto Breath Smell Like?
As mentioned above, the keto breath smell can either be fruity and sweet or as bad as rotting fruit or nail polish remover. This smell is often accompanied by an odd metallic taste in the mouth.
Why Does Keto Make Your Breath Smell?
Being on a ketogenic diet means that your body is constantly making ketones in the place of glucose and using them as a source of fuel. Excess ketones are removed from the body either through your breath or urine. Acetone is one of the three types of ketone made by the body and also released if found to be in excess. This is what makes your breath smell terrible.
How Long Does The Bad Keto Breath Smell Last?
Thankfully this condition is only temporary and will certainly not stay with you for life. You only have to endure this terrible smell as well as the keto metallic taste temporarily until your body adjusts to constantly being in ketosis and the breath subsides before going away completely. The amount of time this takes varies from person to person, typically anywhere from a few days to a few weeks.
Can I Prevent Bad Keto Breath?
The debate on whether you can prevent keto breath seems to be very divided. Some believe that this situation is inevitable since it is a side effect of ketosis and a low-carb diet. However, others believe that there are some simple ways that you can bypass this issue.
These ways include:
- Measuring your ketone levels – For your body to be in ketosis, you need about 0.5 to 3.0 millimoles per liter (mmol/L) of ketones in your body (7). By tracking these levels you are able to note if your diet is causing you to have more ketones than necessary which will eventually affect your breath. Tools to track your ketone levels include blood monitors, breathalyzers, and blood and urine testing strips.
- Exercise More – In ketosis, ketones are the main source of fuel for the body which means when you workout, they are what you’ll be burning – and getting rid of excess ketones in the body. Your body also sometimes gets rid of excess ketones through sweat and we can sweat a lot while working out.
The Bottom Line
If you are willing to try this diet, then it’s best to make peace with the fact that bad keto breath smell is most likely something that you’ll have to deal with. It’s a normal part of getting into, adjusting and staying in ketosis. Thankfully it is only temporary and will go away on its own after a few weeks. Monitor your ketone levels, exercise more, invest in some mints, drink more water and above all, be patient with your body.
This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!
- Breath acetone as a potential marker in clinical practice (2017, pubmed.ncbi.nlm.nih.gov)
- Five Things to Know About Ketones (2019, diabetes.org)
- Hyperketonemia and ketosis increase the risk of complications in type 1 diabetes (2017, ncbi.nlm.nih.gov)
- Ketogenic Diet (n.d., ncbi.nlm.nih.gov)
- Ketogenic diet benefits body composition and well-being but not performance in a pilot case study of New Zealand endurance athletes (2017, ncbi.nlm.nih.gov)
- Ketone bodies: a review of physiology, pathophysiology and application of monitoring to diabetes (1999, pubmed.ncbi.nlm.nih.gov)
- Nutritional Ketosis and Mitohormesis: Potential Implications for Mitochondrial Function and Human Health (2018, ncbi.nlm.nih.gov)