What Is Keyto?

By Lydia Noyes
HighYa Staff
Updated on: Jun 20, 2019

For those considering the ketogenic diet, Keyto is a device designed to give you instant feedback on the amount of acetone in your breath so you can monitor whether your body is in ketosis.

This handheld device pairs with an app to help you make dietary decisions that keep you in ketosis and potentially losing weight.

In this review, we’ll talk about how to use Keyto, what a ketogenic diet is, how the Ketyo app works as well as how it compares to other testing methods and what customers say about their app experience.

We’ve included the insight we gathered from an interview with Keyto founders Dr. Ethan Weiss and Dr. Ray Wu.

How Do You Use Keyto?

When you commit to Keyto, you will receive a lightweight device (the company claims it weighs less than an ounce) that looks and acts similarly to a breathalyzer.

The Keyto runs on one AAA battery that the brand states will last for more than 600 breath tests. Each purchase also comes with four interchangeable mouthpieces and a carrying case.

Keyto works by measuring the levels of acetone in your breath to give you a sense of how much fat you are burning. Acetone levels increase when a ketogenic diet is done right, which we’ll cover in the next section.

Says company founders Weiss and Wu, “Every Keyto has a proprietary nanosensor that detects acetone, a biomarker for fat metabolism, on the breath of users. The more acetone on one’s breath, the more fat they are using for fuel.”

The reported numbers range from one to ten, and the higher the number you score, the further into ketosis your system is.

Below is the Keyto range for ketosis as the company defines it:

  • Level 1 – Not in ketosis
  • Level 2 – Starting Ketosis
  • Level 3-5 – Increased fat burning potential
  • Level 6 – High fat burning potential
  • Levels 7-9 – Extreme fat burning potential
  • Level 10 – Deepest level of ketosis

In this way, you can track whether you are in ketosis in real time and finetune your diet as necessary to maintain progress.

To use the device, you need to breathe into it as long and powerfully as you can, similar to how you would use a breathalyzer.

It will then sync with the Keyto app to display a score from one to ten, with higher scores meaning you are deeper in ketosis. Your overall goal is to keep your Keyto number as high as possible for as long as possible. This ensures that you stay in a prime fat-burning state.

The company suggests taking the test 1-3 times per day when you first start using it, preferably first thing in the morning so that you form a habit and can monitor your baseline over time. For the most accurate results, it’s important to breathe out for a similar length and intensity at every testing time.

About the Keyto App

The Keyto app is available for both Android and iOS devices, and it integrates with the Keyto device to give you real-time feedback on your ketone levels. The app also provides meal plan suggestions and a food guide to help you make keto-approved choices at the grocery store and while eating out.

We found that these guides provided a comprehensive overview of the ketogenic diet, and like that it offers a search feature for more easily finding specific foods.

We also appreciated that the app provides ordering guides for a variety of chain restaurants, including Starbucks, Taco Bell, Panera Bread, and others. In some cases (as with Pizza Hut) the app suggests avoiding the restaurant altogether.

The Keyto app is set up to allow you to track your acetone levels over time so that you can monitor how long your body has been in ketosis and see how that correlates with your weight loss journey.

It’s also possible to join groups through the app to gain support and share your progress with other Keyto users.

What is the Ketogenic Diet?

As we previously laid out in our comprehensive beginner’s guide to the ketogenic diet, this eating strategy is low-carb, high-fat, and moderate-protein, and the primary goal is to starve your body of the carbohydrates it typically relies on for fuel.

This causes your liver to instead turn fatty acids into ketone bodies, which provide a clean, efficient energy source for your brain and body. Ketogenic enthusiasts report that this leads to weight loss and better energy levels throughout the day.

The ketogenic diet is defined by what you can and can’t eat. Permitted foods include olive oil, low-carb nuts, avocados, meat and poultry, cruciferous vegetables, and all forms of cheese. You’ll need to cut sugary and starchy products from your diet, including bread and pasta, bananas, apples, potatoes, rice, and all forms of refined sugar.

According to the AFPA (American Fitness Professionals and Associates), the diet was initially created to treat epileptic children. While it’s still used to alleviate seizure symptoms, the eating strategy has surged in popularity for the general population as a way to lose weight.

Saying that, the diet has some dissenters. In our article on the ketogenic diet, Dr. Annthea Fenwick, an exercise physiologist who has worked with members of the US Olympic team, told us that it isn’t one she recommends to patients.

That’s both because she believes it doesn’t have a thoroughly proven scientific background and because she doesn’t think fat is an efficient fuel source for the body, especially compared to carbohydrates.

She notes following the diet long-term could lead to problems, especially for athletes who perform high-intensity exercises.

The key to following the ketogenic diet is keeping your body in ketosis for as long as possible to maximize fat burning.

Traditional ways to check whether you are in ketosis include blood tests and pee strips. Keyto promises a more convenient solution with their ketone breath analyzer.

Keyto Verse Blood Tests and Ketosis Strips: What’s the Difference?

Keyto isn’t the only device that lets you monitor your ketone levels, but the company claims it is the most convenient. Today, most people rely on blood tests through finger pricks and urine strips to see whether they are in ketosis. Should you consider these methods instead?

While your preferred testing method is a personal choice, one thing to keep in mind is that these methods tend to be single-use, meaning that you will need to buy urine strips regularly to keep testing your levels.

Likewise, some people might appreciate how much less invasive it feels to blow into a tube than it is to measure their bodily fluids.

Another factor is that urine testing is considered to be less accurate than blood or breath and that the accuracy goes down the longer you are on the diet because your body adapts to the change and excretes fewer ketones.

While HVMN shared that blood tests are the preferred way to measure ketones today, breath testing is relatively new to the market, and they state that more research is needed to determine how it compares in accuracy.

How Much Does Keyto Cost?

At the time of writing, the Keyto device is sold exclusively through the company website. You can purchase the device for $99, which gives you lifetime access to reading and feedback on your ketone levels without additional app support.

It’s also possible to upgrade your membership to Keyto Premium for $8 per month. This gives you access to exclusive ketogenic recipes, restaurant guides, the “Keyto Code” (an indicator of which foods are keto-friendly) priority support from the company, and other perks.

Those who become Keyto Premium subscribers at launch time will receive a free shipment of the brand’s KeytoBox, a curated collection of keto-friendly food and snacks that retail for over $80 in total.

If you wish to contact the company directly for more information about their pricing and return policy, you can do so at hello@getkeyto.com.

What Do Customers Think of Keyto?

Though the Keyto device was new at the time of writing, we found online reviews for the app we felt were worth considering.

The Keyto app earned 2.6 stars after 37 reviews on Google Play. The biggest critique we noticed was that the app struggled to connect to the device and that it was glitchy when it loaded.

Many people noted that they couldn’t access the supplementary material on the ketogenic diet, and others reported that it often crashed. A few people stated that they didn’t think the device was accurate, as they occasionally blue high numbers (4-6) after eating carbohydrates earlier in the day.

Others wrote that they thought the device worked as described and that the accompanying app helped them stay motivated to stick with the keto diet and that it helped them determine which foods were permitted in a pinch.

Our View: Should You Consider Keyto?

From this research, do we think that Keyto makes sense for those following the ketogenic diet?

The product founders shared with us that they want Keyto to be an all-encompassing system, meaning that someone who doesn’t know anything about the ketogenic diet could buy the device, download the app, and get started right away.

We think Keyto delivers on this goal, as the product’s app offers a comprehensive overview of how to follow the eating strategy and it includes shopping lists, meal planning suggestions, and even fast food eating guides.

The negative reviews we noticed were based primarily on the app being buggy while in the early stages of development, so it’s reasonable to expect that these issues will improve over time.

If you’re looking for a convenient way to track your time in ketosis, it’s hard to argue against breathing into a tube when the other alternatives are testing urine or blood. Likewise, you might save money over time by not buying single-use testers.

Whether or not the ketogenic diet makes sense for you from a health perspective is a different question, and it’s one with a nuanced answer. We recommend starting your research process with our comprehensive guide to the ketogenic diet.


Read 8 Keyto Customer Reviews and Complaints

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Average Customer Rating: 1.9
Rating Snapshot:
5 star: 1 4 star: 1 3 star: 0 2 star: 0 1 star:  6
Bottom Line: 25% would recommend it to a friend
Showing 1-8 of 8
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  • Avoid

    • New York,
    • Dec 10, 2019
    • Verified Reviewer

    The device takes an extraordinarily long time to warm up. The data was never accurate when compared to a blood or urine test. The device stopped stabilizing after about 20 uses and now just gives an oops error when attempting use. In my opinion, this is a cheaply made "gimmick", not worth 5 cents, let alone 100 dollars. Avoid!

    Bottom Line: No, I would not recommend this to a friend

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  • 2 out 2 people found this review helpful

    Works (for me)

    • Destin, FL,
    • Sep 23, 2019
    • Verified Reviewer

    The only reason I haven’t given it 5 stars is because I cannot independently verify to date that the thing is accurate. But it IS consistent, and the inference based on historic experience with the keto diet and testing is the data is accurate "enough." I am a believer that in theory, the breathalyzer is more accurate than test strips or even blood sampling. Maybe once out of every ten pairings the thing doesn’t exactly pair correctly with the app and I’ll need to restart the app. Never even thought about it. Any ketone breathalyzer will take time before you can use, needs to calibrate the baseline air, among other things (Keyto refers to heating element rising to 400 degrees).

    Bottom Line: Yes, I would recommend this to a friend

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  • 2 out 9 people found this review helpful

    Terrible device capitalizing on the Keto craze

    • California,
    • Sep 5, 2019
    • Verified Reviewer

    It measures my Keyto level at their "8" regardless of if I'm between 5mmol/L or 2mmol/L, when I use an actual tester with my blood. Maybe this device will motivate some people, but it's not a serious product. Avoid.

    Bottom Line: No, I would not recommend this to a friend

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  • 6 out 6 people found this review helpful

    Helps me keep diet top of mind

    • Aug 24, 2019
    • Verified Reviewer

    I've been using Keyto for the last 2 months consistently. The feedback it provides is extremely helpful and reassuring and seems to be pretty accurate when cross-checking with strips.

    Super helpful to see how different foods affect my Keyto score, and it has helped me learn a ton about my body and the effects that certain foods have on me. It does take a bit long to warm up (around 45 seconds) - would prefer if this was more instantaneous. Would also love if the device was a little bit smaller, but it's not a deal-breaker.

    Recommended Keyto to 2 of my friends and now we compete daily for the lowest keto score. I have lost about 8lbs on the keto diet. My goal has been to lose 1lb a week and so far I'm right on target. Overall, great fun product that can help you track and quantify your level of ketosis.

    Bottom Line: Yes, I would recommend this to a friend

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  • 0 out 5 people found this review helpful

    2nd device stopped working as quickly as the first one

    • Austin, TX,
    • Aug 16, 2019
    • Verified Reviewer

    I purchased the Keyto device and app and was pretty pleased with it. It does take forever to warm up each time but it was cool to have feedback and confirmation so I was willing to work with that. But after only 3 days I kept getting an error that there was a contaminant in the air and the device couldn’t work. I emailed support and heard back immediately! I was impressed. They also quickly sent me a new one. That one lasted only a week and as of yesterday gave me the same error. I emailed support again and have not heard anything back. Each time I got this error I tried different locations and was even in two different states. So it is nothing in my environment. I’m betting a lot of people have this problem.

    Bottom Line: No, I would not recommend this to a friend

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  • 5 out 10 people found this review helpful

    Cheap piece of garbage

    • Seattle, WA,
    • Jul 22, 2019
    • Verified Reviewer

    It is hard to pair, takes forever to "warm-up" for each reading, and when you do finally blow, the results change almost as frequently as you blow. In other words, it is not accurate.

    They have basically repackaged one of those cheap Chinese breathalyzers for Keto. It is equally crappy, but much more expensive.

    Having used urinalysis strips, blood test strips, cheap breathalyzers, and the Keyto, I can tell you that this thing is just an expensive way to sell you more (crappy) stuff.

    This thing is a rip-off. Don't buy it.

    Bottom Line: No, I would not recommend this to a friend

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  • 7 out 9 people found this review helpful

    Doesn't work

    • Denver, CO,
    • Jul 17, 2019
    • Verified Reviewer

    Device stopped working after a month. Their support told me they don't know what is wrong with it. It crashes every time it warms up. They emailed me about a month ago to post a review and I did and they never posted it online. They are filtering out negative feedback and suckering people into buying this garbage.

    Bottom Line: No, I would not recommend this to a friend

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  • 18 out 21 people found this review helpful

    Just get the blood test

    • Miami, FL,
    • Jun 12, 2019
    • Verified Reviewer

    Awful. The product is a cheap, $1 piece of plastic with a battery that is sold for 100 times more. Very inaccurate compared to a blood test or even pee strips. Besides inaccuracy, the company has released the product with billion bugs and limitations. If you ever log out of your profile - you gotta get a new Keyto. If you create a new profile - you gotta get a new Keyto. Absolute waste of time, health, and money.

    Bottom Line: No, I would not recommend this to a friend

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