Key Takeaways:
- Keto breath is a common side effect of ketosis due to the release of acetone in your breath.
- It often smells fruity or like nail polish remover, but it typically fades as your body adapts.
- While it’s hard to completely prevent, keto breath is usually temporary and can be controlled using simple strategies.
Starting a keto diet can bring about noticeable changes in the body as it adjusts to this low-carb, high-fat way of eating. For those who are new, one of the more surprising side effects is a change in breath odor. You may notice a fruity or metallic scent, which is a phenomenon commonly referred to as “keto breath.”
In this article, we will explain why keto breath happens and what you can do about it.
What is Keto Breath?
Keto breath is a distinctive odor that some people experience when following a low-carb or ketogenic diet. It results from the body producing acetone, a type of ketone, which is then exhaled. It’s a common side effect during the initial phase of the diet as the body transitions to burning fat for fuel instead of carbohydrates.
Research shows that breath acetone is a reliable indicator of ketosis. In the context of patients with epilepsy who are on a ketogenic diet, measuring breath acetone is particularly useful because it helps understand how ketosis relates to seizure control and how well the diet is working [*].
For those following a ketogenic diet for weight loss, the presence of acetone in their breath (keto breath) signals that their body is burning fat for energy and that the diet is working as intended [*].
What Does Keto Breath Smell Like?
Keto breath typically has a fruity, sweet, or metallic smell, which is often compared to overripe fruit or acetone, which resembles nail polish remover. The smell can vary in intensity and is usually most noticeable early in the diet or when a person is in a deeper state of ketosis.
How Long Does Keto Breath Last?
Keto breath is usually temporary and generally lasts from a few days to a few weeks, depending on how long it takes for your body to adjust. As your body becomes more efficient at using ketones for fuel, the excess production of acetone decreases, and the odor tends to subside within a few days to a few weeks.
Although it can be bothersome at first, most people find that the odor becomes less noticeable as they continue with the diet and their metabolism adjusts. Thankfully, there are steps you can take to help mask keto breath.
How to Get Rid of Keto Breath
While you can’t completely eliminate keto breath until your body adapts to the diet, there are several simple strategies that you can try to manage it:
Lower your protein intake
When you eat too much protein on a ketogenic diet, your body breaks it down and produces ammonia as a natural byproduct. Ammonia has a strong, unpleasant smell, and when there’s too much of it, it can contribute to bad breath.
Reduce this effect by moderating your protein intake. Yes — protein is a key part of a keto diet, but eating too much can lead to higher ammonia levels in the body, which intensifies keto breath.
In the meantime, focus on eating more healthy fats, like avocados, nuts, and olive oil. This is a simple way to make sure you’re getting most of your calories from fat.
Increase your carb intake gradually
When you reintroduce carbs, your body shifts from burning primarily fat to using carbohydrates for energy, which lowers ketone production and, consequently, the amount of acetone released in your breath.
We recommend reintroducing a small amount of carbohydrates, such as 10-20 grams of low-glycemic vegetables (like spinach or broccoli) each day. This small increase in carbs is not enough to kick you out of ketosis.
Chew sugar-free gum or mints
Sugar-free gum or mints help manage keto breath by stimulating saliva production, which helps wash away bacteria and ketones in the mouth that contribute to the odor.
Additionally, these products often contain ingredients that neutralize or mask bad breath temporarily, which provides a fresher scent.
Opt for mints with fewer carbs per serving to stay within your daily carb limit or look for those that contain keto-friendly ingredients like xylitol, erythritol, or stevia. These are sweeteners that won’t spike blood sugar levels or kick you out of ketosis.
Practice good oral hygiene
Proper oral care not only helps control bad breath but also promotes overall dental health by preventing plaque and bacteria from accumulating.
Brush your teeth at least twice a day and floss daily to remove debris and bacteria between your teeth that brushing alone can’t reach. Since bacteria and food particles can linger on your tongue, using a tongue scraper daily helps remove these substances and will keep your breath fresher.
Drink plenty of water
Drinking plenty of water helps manage keto breath by diluting the concentration of ketones, such as acetone, in your body. Since ketones are excreted through your breath and urine, staying well-hydrated assists in flushing them out more efficiently.
Moreover, adequate hydration prevents dry mouth, which is a common contributor to bad breath. Keep a bottle with you at all times, so you can sip water wherever you go. It’s a constant reminder to stay hydrated!
Can Keto Breath Be Prevented?
Keto breath can be managed, but it’s challenging to completely prevent since it’s a natural byproduct of the body burning fat for fuel in ketosis. However, there are ways to reduce its intensity, such as adjusting your macronutrient ratios to lower ketone levels and drinking plenty of water.
The Bottom Line
Keto breath is a natural part of your body’s transition to burning fat for energy, and while it can be a bit uncomfortable, it’s a sign that your ketogenic diet is working.
Know that this is just one part of your journey toward better health. As your body adapts, this side effect will diminish, and you’ll continue to reap the long-term benefits of ketosis. Stay patient and focused on your goals.
References:
- Musa-Veloso, K., Likhodii, S. S., & Cunnane, S. C. (2002). Breath acetone is a reliable indicator of ketosis in adults consuming ketogenic meals, American Journal of Clinical Nutrition, 76(1), 65–70. https://doi.org/10.1093/ajcn/76.1.65
- Anderson, J. C. (2015). Measuring breath acetone for monitoring fat loss: Review. Obesity, 23(12), 2327–2334. https://doi.org/10.1002/oby.21242