Finally understand what's working for your body—no guesswork, no gimmicks.
Key to Health is designed for high-achieving, busy people who want to look better, feel better, and optimize their long-term health without spending hours on complex routines.
Backed by science. Guided by AI. Built for real life.
Our breath sensor gives you real-time feedback on your body's fat metabolism—so you can see what your daily choices are actually doing, not just hope for the best. Pair that with smart AI coaching, and you have a system that adapts to you.
What you'll get:
• Real-time fat metabolism tracking with our breath acetone sensor
• Personalized coaching from KEY, your AI health guide
• Clear, science-based goals and progress tracking
• Tools to build strength and support long-term health
• Eat what you love—no restricted foods, no keto required
Meet KEY: Your 24/7 AI Coach
KEY learns from your habits, adjusts your plan, and guides you every step of the way. Instant support and personalized guidance, whenever you need it.
Grounded in clinical evidence. In a published clinical trial, participants following the Key to Health program lost an average of 10% total body weight over 48 weeks.
No fad diets. No extreme routines. No forbidden foods. Just real progress, made easy.
This app and breath monitor are for adults 18 years and older.
Subscription pricing and terms:
Key to Health offers an auto-renewing monthly subscription at $49.99/month to provide you with unlimited access to the Key to Health Premium collection while you maintain an active subscription.
Payment will be charged to your Apple Account when you confirm the initial subscription purchase. Subscriptions automatically renew unless auto-renew is turned off at least 24 hours before the end of the current subscription period. Your account will be charged for renewal within 24 hours prior to the end of the current period at the current subscription price. You may manage your subscription and turn off auto-renewal by going to Settings > Manage Subscription on your device after purchase. Any unused portion of a free trial period, if offered, will be forfeited when you purchase a subscription, where applicable.
Read more about our terms and conditions here:
Terms of service: https://keytohealth.ai/terms
Privacy policy: https://keytohealth.ai/privacy
[update] App got fixed, and unnecessary audio was removed as well. It’s now much less invasive, and easier to use. Well done!I bought my Keyto device to read my blood ketone levels, natch. I don’t care about their app beyond getting those readings. Of course the app is always nagging me for more attention and more personal data, which until now has been avoidable, if annoying. No matter how hard the developer tries, I’m not going to shift the management of my health tracking data into their app. I just need the app the get the ketone reading out of the device I purchased. But with the most recent app update, I can no longer just get my ketone data from my device without entering a number of personal metrics into the app. This is a deal breaker for me, and has now rendered my Keyto device unusable. Like so many people, I am exhausted daily by the many information-sucking monetization strategies employed by companies today. Keyto: The best relationship you can build with me is to keep your device simply doing what I bought it to do: measure my ketone levels.
Best Ketone Breathe Analyzer in the Market!
EngTiang
I’ve been using Keyto since March 2019 as one of the few early batches of Indiegogo Kickstarter. Been on a ketogenic lifestyle for almost 5 years. Continuously with the exception of biohacking by carb cycling to see the effect! Keyto works! When I carb cycled, ketone measurements was very very weak! Took another 2-3 days to fully recover to level 6-7(my average days)This is my second breathe analyzer device. Having tried other brand, blowing for acetone in the bottom of our lung...can be very hard!It is still debatable where blood measured ketone or breathe measured proxy; acetone is better? For someone who is serious about biohacking and needs measurement throughout the day, I don’t think blood ketone strip is justified due to much higher cost. Unless, someone can come up with a continuous reading monitor for ketone like a CGM device; I prefer breathe analyze hands down!Thanks to Dr. Weiss and the rest of the Keyto Team. A job very well done for the first version!Is Keyto perfect? How can it be for the first device by them?Room for improvement? You bet!My wish list:1. Measuring while offline(no internet connection) Useful while traveling/flying intercontinental flight with no internet access. I would like to see the effect of high altitude on my fasting and ketone production.2. Warming up period for device when cold.Takes too long when taking first reading when device is cold(not used in last few hours). On an average, I would take 2-3 readings for a more accurate picture. Could this be the sensor acting up? I’m not sure. Hopefully the technical team can tell me. For a long term success, the above issues are critical!
Surprise! I adore this entire package! And I’m staying in track!
clockie
I tended to stray from my weight and health goals daily, promising myself... ok... I’ll start again tomorrow. Well, hundreds and hundreds of tomorrow’s later, I saw this on my Instagram. So, being the tech geek that I am, I ordered it. It was so much fun and it made me an honest woman within a week. I can’t hide anymore with my new toy! It’s fun to use it after eating to see what affects my Ketosis. I feel wonderful! I’m losing unwanted pounds, and I’m having fun, while learning to be true to myself. Good thing. I also got a Keyto box full of incredible snacks and foods. The app is a great resource of data I never knew. Loving this!!! Thank you!Update: still loving this product! It keeps me honest! ❤️❤️❤️❤️❤️
Amazing device!!!!
SaintRhyan
Honestly I can’t say enough good things. As someone who has used ketosis for weight loss and lifestyle I love the fact that it lets you know right where you are from the start of your journey on. So when you’re feeling bad in the beginning it’s easy to look at your number and see exactly where you are and it gives you motivation to keep going. The app is incredible, lots of tips and helpful information. It’s easy to use, accurate and so much cleaner than strips. The other testers that use your breath don’t test properly and do not use the proper aspects of your breath for the most accurate reading. All in all, it’s easy, convenient and accurate. What more could you ask for.
• Bug fixes and performance improvements
Version 4.0.1
The developer, Keyto, Inc., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Linked to You
The following data may be collected and linked to your identity:
Health & Fitness
Contact Info
User Content
Identifiers
Usage Data
Diagnostics
Privacy practices may vary, for example, based on the features you use or your age. Learn More
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More