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What Keto Breath Is and How To Avoid It (or Fix It)

Have you noticed a change in your breath since beginning the ketogenic diet? Keto breath is a very real phenomenon that affects a lot of keto dieters, especially at the beginning.

The bad news is that bad breath can be a side effect of the keto diet, and there are a few reasons for that, which we'll get into shortly. The good news is that you're not doomed to have keto breath forever. There are some measures you can take to reduce and eliminate this problem and proceed unscathed with your low-carb, high-fat diet. 

What Is Keto Breath?

Keto breath is one of the common side effects of transforming your metabolism and achieving ketosis. Some keto dieters describe keto breath as acidic or even fruity, while others describe it as a metallic or chemical smell or taste. Unfortunately, it's not something that flossing or better oral hygiene will remedy (although good dental health is incredibly important in its own right). 

Surely you know what standard halitosis smells like. It's the smell of decay, old food and stagnation. Keto breath is different because the cause is different. 

But don’t worry, it’s only temporary (if you experience it at all). Much like other keto side effects, keto breath is only an early side effect that will fade once you’re fat-adapted.

Why Does Keto Breath Happen?

keto breath: woman removing her nail polish

There are a few explanations for this weird fruity breath or metallic taste. When your body reaches a state of ketosis, some of the ketones you're producing are exhaled through your breath—this is why it's possible to test your ketone levels using a breath meter. Although we personally believe that ketones from the blood are the best method of testing ketones, there are some that utilise a breath meter. 

Acetone is one of the ketone bodies your liver produces when you switch over to a ketogenic diet. When your body switches from using glucose for fuel to using fat, your liver goes into overdrive, producing ketones from fat, which, as they build up, are exhaled through your breath [1]. If you like to get manicures or paint your nails, you know that acetone is a key ingredient in nail polish remover. That same chemical smell of polish remover is part of what contributes to keto breath. 

Some individuals also report that their urine smells different or like nail polish remover as well. It's for the same reason, but instead of excreting acetone in your urine, your body excretes acetoacetate, a different ketone body.

It's also possible to develop keto breath if you're not getting your macros exactly right. Your body produces urea and ammonia to digest protein, and sometimes the transition to the keto diet can be a little rocky with macro ratios [2]. It's easy to overeat protein if you're not used to eating a high-fat diet, but doing that can create an excess of ammonia, which comes out in breath (and again, urine). 

Make sure you're calculating your macros accurately, and pay attention to your protein intake just as much as you are your carbs and healthy fats. This way, you'll maximise your success on this diet and minimise your chances of ketosis breath. 

How To Avoid Keto Breath

keto breath: woman drinking water

The silver lining to having weird breath or odourous urine is that you'll know for sure that you've reached a state of ketosis. The goal of the ketogenic diet is to optimise your metabolism by swapping your fuel source from carbohydrates to fats. As you reduce your carb intake (<20g per day) and up your intake of fatty acids, you'll begin that switch. How well you manage the change will make all the difference when it comes to avoiding or minimising side effects (like the keto flu or keto breath). 

But even if you do experience a few side effects, they don't have to last long. In fact, some of the remedies for keto breath are great ways to avoid many of the other potential side effects of this diet, like fatigue, constipation, foggy-headedness and dehydration.

Steps to Minimise or Eliminate Ketosis Breath

Although not everyone who begins the keto diet will experience keto breath, it's a good idea to follow these steps as you begin this lifestyle change. 

  1. Confirm Your Macros

This step is all about ensuring that you've properly calculated the ratio of fat to carbs to protein that you as an individual should be eating. We know that the ideal keto diet ratio is 75% fat, 20% protein and 5% carbohydrates, but you want to make sure that you've correctly determined what these percentages mean in grams for your body weight and your fat loss goal. 

  1. Hydrate Properly

Proper hydration is by far the most important way to avoid most of the unpleasant side effects of the keto diet, including keto breath and keto flu. Proper hydration is more than just drinking lots of plain water, especially in the context of this way of eating. 

You lose water weight as your body burns through its glycogen stores [3]. Because your body is changing how it stores and uses energy, it will be dumping water at the beginning. Along with that water weight will go lots of electrolytes. It's really important to add electrolytes back in to avoid the keto flu. 

But as far as keto breath goes, staying hydrated helps you avoid dry mouth and also washes away the excess ketones on your breath. It also helps dilute your urine, which can reduce the odour there as well. Get creative by adding lemon and mint to your water for additional breath freshening benefits. 

  1. Monitor Your Ketone Levels

Actively monitoring your ketone levels is something you should definitely do, at least in the first few months of your new keto lifestyle. While it's not always convenient to have urine test strips or a breath monitor on you at all times, knowing where your ketone levels are is a great way to find out if you're producing enough or too many ketones. Too many ketones aren't dangerous for your health, but they do enhance the breath smells you're trying to avoid, so finding that sweet spot is key.

  1. Consider Adding a Few More Carbs

If you find through repeated testing that your ketone levels are always on the high end, consider adding in a handful of carbs. Don't worry, if you're testing regularly, you'll know if you go overboard by accident. The idea behind adding in a few more carbs is to reduce ketone production in your liver to an amount that's not so apparent upon exhalation. If you've been eating 15 grams per day, consider going up to 20 and see if things change. After being in ketosis for a number of months, you might find that your own personal level of carbohydrate can increase (to <50g of carbs per day for example). Testing with a ketone and glucose monitor is key. 

  1. Oral Hygiene

We know we said at the beginning of this article that oral hygiene had little to do with keto breath. But having good oral hygiene is still a really good idea. Use mouthwash and floss daily to ensure that bacteria isn't accumulating in your mouth to compound keto breath. 

Keto Breath Is Only Temporary

man using dental floss

Just like so many of the other symptoms of the keto diet, the best way out is through. Stick with your plan and your symptoms will fade after a week or two. Keto breath is a temporary side effect of the transition to a high-fat, low-carb diet. Once your body has adapted to this way of eating and you've found good metabolic balance, your keto breath should disappear. 

While some people never experience keto breath, it's still incredibly important to stay hydrated, make sure your macros are correct for your goals, monitor your ketones and take good care of your mouth. If you're just starting out on the keto diet, find out how to get into ketosis safely and what to expect.

All information provided on our website and within our articles is simply information, opinion, anecdotal thoughts and experiences to provide you with the tools to thrive.

It is not intended to treat or diagnose symptoms and is definitely not intended to be misconstrued for medical advice. We always advise you seek the advice of a trained professional when implementing any changes to your lifestyle and dietary habits.

We do however recommend seeking the services of a trained professional who questions the conventional wisdom to enable you to become the best version of yourself.


[1] https://academic.oup.com/ajcn/article/76/1/65/4689461 

[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4527031/ 

[3] https://pubmed.ncbi.nlm.nih.gov/25911631/


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