This is my review of the Biosense ketone breath meter. I have been regularly on and off keto for over 7 years now, and here’s my experience.

Biosense is the most accurate breath ketone monitor with a high price tag. Its accuracy is verified by clinical trials and it’s a FDA-registered Class I medical device.

In this Biosense review, I will analyze the device, its accuracy, drawbacks, and alternatives.

Let’s get started!

• What is Biosense
• How does it work
• Accuracy
• Ease of use
• App
• Price
• Drawbacks
• For whom is it for
• Alternatives

What is Biosense?

Biosense is the most accurate breath ketone monitoring system on the market. It’s a FDA-approved ketone breath meter backed by clinical trial data, confirming its accuracy. (1) This is the main differentiator from alternatives like Keyto.

It’s a convenient pocket-sized device that tells you if you are burning fat or glucose for energy.

I use Biosense because I want to understand how certain foods and exercises impact my ketone levels. I like how it’s very non-invasive, even my daughter used it without a problem.

I found through my testing that although it’s the most accurate device on the market, it’s only accurate when I use it the right way. 

I needed to measure 3 times per day and during the same time.

I also discovered that I need to keep at least 5 minutes between measurements, so the residual ketones have time to dissipate from the sensor.

Pros

• Most accurate ketone breath meter on the market
• Uses end-of-breath sampling for the most accurate reading
• FDA-registered Class I medical device backed by clinical trial data
• Has a screen, so you don’t need to use a smartphone first thing in the morning
• Automatically syncs with the app for convenient tracking
• Haptic feedback tells you when to stop breathing into the device

Cons

• Takes time to warm up before you can use it
• Average battery life of 2-4 days
• $74.99 for recalibration every 6+ months

How Does Biosense Work?

The Biosense ketone monitor measures acetone levels from your breath and reports your level of ketosis. (2)

It’s unique because instead of using regular breath analysis, it uses a method called “deep lung sampling”. This takes the acetone measurements from the last part of your breath, ensuring the most accurate results. 

I really like the small display that the device has. It shows your results on its screen, so you don’t need a phone handy. This is a nice touch because I hate watching a screen in the mornings.

*There’s a rough 1:10 relationship from ACE and BHB. But this is comparing two very different things.

The Biosense technology shows your acetone levels in units called ACEs. There’s a rough 1:10 relationship between ACEs and Beta-hydroxybutyrate (3), although they are totally different things.

For example, 5 ACEs equal roughly 0.5 mmol/L of blood ketone levels (BHB). 

I like that every measurement is automatically saved and synced to my phone via Bluetooth. And I can analyze results again anytime in the Biosense app. 

Plus, the results are shown with a color scheme, which in my opinion, makes it 10 times easier to understand the “dry number” result. 

How Accurate is Biosense?

Biosense sets itself apart with its impressive accuracy as a ketone breath meter. Successful clinical trials have confirmed the accuracy and the correlation between breath ketone (acetone) and blood ketone (BHB) levels. (4)

The high accuracy is achieved through three main factors:

• Sensitive sensor – The sensor is extremely selective to acetone, compared to many cheap keto meters that are just repurposed alcohol breathalyzers.

• End of breath sampling – Most gases in your breath are most concentrated at the end of your exhale. A pressure sensor listens as you exhale, waits for the end of your breath, and a pump pulls the last part for analysis.

• Sealed flow cell – All the analysis is contained inside the sealed flow cell inside the device. Compared to other devices where the sensor is visually seeable and exposed to the outside. This is a problem because the sensor mixes your results and outside air and may not get that precise results. 

But no matter how accurate the technology is, at the end of the day what matters the most is how you take measurements. This will make or break the consistency of your results.

Tips to Get Accurate Readings Consistently

At the beginning of reviewing Biosense, I had inconsistent results for my acetone levels. This lasted until I tested and understood how to take better measurements. Here are the tips that worked for me.

1. Always follow the steps on the device screen. Do not blow into the device if the device is still warming up. 
2. Breathe into the device with a moderate force until the device gives you 2 short vibrations. I really like this haptic feedback that guides me when to stop.
3. Try to get a normal lung full of breath, if you don’t blow enough, it gives you an error. For example, my daughter tested it, and the first blows got errors because of the low pressure. If the device shows a result of 0 then you are breathing too hard into the device.
4. Wait at least 5 minutes between measurements because it takes about 5 minutes for the residual ketones to dissipate from the sensor.
5. Avoid testing right after alcohol, breath mints, anything with sugar alcohol, or anything with minty flavor (toothpaste, mouthwash). Wait at least 1 hour after using those. These will show artificially high results because the sensor is so sensitive.
6. As your ketone levels are highly variable throughout the day, up to 50% +- Biosense suggests measuring 3 times per day during the same times. The foods you eat and your activity levels cause the fluctuations.

Is Biosense Easy to Use?

Yes, the Biosense ketone breath analyzer is extremely easy to use. I just breathe into the device and it shows my ketone levels. No more pricking my finger! 

I really appreciate the device screen, which shows my ketone levels quickly and conveniently. I no longer need to watch a phone screen first thing in the morning.

It’s far more accurate than anything else I’ve tried. The device gives a score in ACE units, which are kind of like blood ketone equivalents. 

But remember, blood and breath ketone molecules aren’t exactly the same. The blood ketone is called Beta-hydroxybutyrate (BHB), and the one you exhale is acetone. 

So, if you get a reading of 13 ACE units, just divide it by 10 to get a rough estimate (1.3 mmol/L) of your blood ketone level. 

Plus, I really like that it’s an FDA-registered Class I medical device. 

How to Get a Reading

1. Turn on the Biosense monitor and wait until it heats up. Once it’s ready, it gives an indication on the screen. (~1-2 minutes)
2. Then push the button again and take your breath (~2-3 seconds)
3. Once it says blow, breathe into the device with moderate pressure until you feel 2 short vibrations indicating you to stop. (~10 seconds)
4. Look for a success message saying that the measurement was successful and wait for results. (~10 seconds)
5. Optional: You can also open the app and analyze your past measurements there.

Biosense App

The Biosense app is a great bonus that comes with the Biosense ketone meter. 

This app isn’t necessary for getting a reading, but it provides a handy way to review past measurements and gives insights into ketone levels patterns and statistics. 

• It has an activity, meal, and weight tracker – So you can add additional info and get a holistic overview of your weight loss and health progress.

• It has historical measurements (in ACEs), the depth of ketosis (Ketone Dose), fasting tracker/timer, nutrition, and exercise guides – So you understand your state of ketosis and development better.

• It also has app integrations like Apple Health, Google Fit, Nutrisense (continuous glucose monitor) – So you can sync your ketones data to other apps like Nutrisense and combine your ketones levels with blood glucose levels and much more.

The app is very easy to use and also has a resources section with guides on how to achieve and maintain ketosis. This is especially helpful for beginners first time following the ketogenic diet.

Biosense Price

So, how much does Biosense cost? The device has a $299 one-time upfront fee.

I honestly believe that the $299 price tag is a steal for a pocket-size clinical device that is almost as accurate as blood monitors. 

PS! Use a Biosense ketone discount code “BODYKETOSIS” to get $15 OFF.

Think about it: you can get clinically accurate readings anywhere you are. You get a screen + free app with all the perks. This is definitely worth the money in my book.

The Biosense package includes:

• Biosense fat burn tracker
• Quickstart guide
• User guide
• Charging cable (*without the power brick)
• Travel case
• 2 extra mouthpieces

But what bugs me is the regular recalibration, needed about every 6 months, which will cost $74.99 each time after the first year. 

This means a $74.99 fee x 2 times per year / 12 months = $12.5 per month (annually).

It’s just annoying to do the process and pay for it every time. But if getting the most accurate measurements is important for you, then it’s 100% worth the price. 

Because what’s the alternative? Going back to pricking my fingers 3 times a day? No thanks!

Biosense Drawbacks

For the most part, Biosense is awesome because it’s so accurate and actually a medical device.

However, during my Biosense ketone meter review, I found several problems that bugged me a lot.

1. Need for Recalibration

The main unanticipated problem I have with Biosense is the need for recalibration. To ensure medical grade accuracy, sensor recalibration is needed every 6 months. 

The two main signs that your Biosense sensor needs calibration are: 

• It has been 6 months since your last calibration
• Consistently measuring 0 ACEs

The problem is that you cannot recalibrate the device on your own, but you need to send it to their lab, which can take from 6-10 days.

1. Biosense provides you with a shipping label for you to send the device.
2. You will need to send the device to the manufactory, where trained technicians will do the recalibration.
3. Biosense sends the device back to you. 

The surprising part for me was that the sensor calibration that any sensor recalibrations that fall outside of the 1-year warrantee time frame will cost $74.99. Sensor recalibrations are covered within your 1-year warranty. 

So, in addition to the initial price, after the first year, my average monthly additional cost will be $12.5. This means a $74.99 fee x 2 times per year / 12 months = $12.5 per month.

I understand the need for calibration, especially in the case of a medical device, but damn it’s annoying to do the recalibration process and to pay for it.

But I also believe, that if getting precise measurements is important for you, then it’s worth the effort. Because what’s the alternative? Going back to pricking my fingers 3 times a day? No thanks!

2. Short Battery Life

As a Biosense user, I’ve found that the battery life isn’t quite up to snuff. 

Although the device comes with a rechargeable battery that can last a few days, it really depends on how much you use it. 

For about 1-5 measurements per day, I get about 2-4 days of battery time, which, I’m going to be honest, is surprisingly low. 

Despite this, I found myself having to charge it almost daily, which was a bit of a hassle. 

Interestingly, the device runs additional sensor diagnostics when asleep and plugged in, which can help maintain accuracy but also drains the battery. 

You’d think that with the $300 price tag, they’d include a power brick, but nope – you have to get that separately. It takes about 2-3 hours to fully charge with the provided micro USB cable. 

3. Long Warmup Time

One issue that I’ve noticed with all ketone breath analyzers, including the Biosense, is the long warmup time. 

It typically takes around 2-3 minutes to warm up before I can take a measurement, but this can sometimes stretch up to five minutes. 

I understand that the warmup time can vary based on how often you use it, when it was last calibrated, and the room’s temperature. 

While this is a technical limitation rather than a fault of the device, it can be really annoying when I’m in a rush. 

Despite this, the slow warmup is the price we need to pay to get the most accurate breath ketone reading.

4. Supports 1 User Profile

Another downside I stumbled upon with the Biosense device and the app is that they only support one user profile. 

This became an issue in my household as we all started testing it out after meals, and the readings got all jumbled up. 

When multiple people use the device, all the test results end up in the same mobile app timeline. 

So, I found myself having to manually delete my kid’s results to keep track of my own readings. 

Now, this isn’t necessarily a problem, but it’s definitely a limitation worth considering, especially if you’re planning on sharing the device with others. 

5. Messy Homepage

I have a weird gripe with many brands these days, including Biosense. Their website just doesn’t build much trust for me. 

The design is basic and doesn’t have the modern feel I expect from a top-notch brand. Plus, there’s just a contact form, no email or phone number. 

Also, they’ve buried their shipping and returns info deep in the FAQ pages. Sure, it’s there, but it’s not easy to find. 

As a customer, I’d like them to be more upfront with their contact details and shipping info. 

For Whom is Biosense For?

I believe the Biosense breath ketone meter is perfect for anyone who’s serious about their health. 

Whether you’re an athlete wanting to improve body composition and mental acuity or simply someone seriously wanting to shed some pounds, Biosense is for you. 

It gives super accurate results without the need for finger pricks three times a day. If you’re just starting with a keto diet, you’ll get great value from this device. 

But, if you’re unsure about pursuing a keto diet, Keyto might be a better value. 

Biosense Alternatives

Here are the best alternatives to the Biosense tracker based on specific use cases. All of them are good products for doing certain things very well.

1. Lumen – Best for low-carb diets

Lumen is the best metabolism tracker for low-carb dieters. It’s similar to Biosense, but you can lose and track your fat burn without the restrictive ketogenic diet. 

2. Keyto – Best value for keto dieters

Keyto is also a ketone breath analyzer that measures your acetone levels, but it offers way more value for beginners. It’s not a medical-class device, but it gets the job done and costs only $99.

3. Fora 6 Connect – Best blood ketone meter

Fora 6 Connect is the gold standard in ketone and glucose blood measurements. It provides you with the most accurate readings possible every time.