I Am A Keto-Friendly Cardiologist And I Love Keyto

The skeptical cardiologist has become more selective with regard to who he will accept as a new patient.  In practical terms this means I now call patients who want to see me and discuss with them why they want to see me, how they were referred or heard about me, and what their expectations are.
This might seem a little odd but turns out to be an excellent way for me to meet and smooth entrance for these newbies into my practice and gather important records and recordings prior to the first visit.
Recently, when I asked one of these potential patients why they had sought me as their cardiologist, the wife told me that through her internet research she had gleaned that I was a “Keto-friendly Cardiologist.”
Given that I have challenged conventional dogma on the dangers of dietary saturated fat and cholesterol and have written about ketosis (see here and here) a few times on this blog and defended Dr. Atkins I do actually consider myself “keto-friendly”.   However my prospective patient’s wife was not aware of the skeptical cardiologist as a blog writer.
How or why I was identified as Keto-friendly cardiologist was not clear.
I realized I needed to make it perfectly clear. It is now time to come out of the keto closet.
I am a “Keto-friendly cardiologist”!
I have dozens of patients who have been very successful using very low carb/high fat diets to help them lose weight and gain control of their diabetes and hypertension.
I don’t poo poo low carb high fat diets and I think they are vey compatible with a heart-healthy existence.
(I also advocate my version of a “plant-based diet“.)
In fact, lately I’ve gone back to dabbling with a Keto Diet myself.
To aid me in the dabbling I have found a device called Keyto to be the key to success and understanding of my ketosis.

Keyto: Breath Sensor for Ketosis and Weight Loss

When I went back to dabbling with ketosis in early 2019 I was using the Keto-Mojo finger prick device to measure my blood levels of beta hydroxybutyrate. I liked the precision this offered  compared to urine dip sticks but grew to dislike the need to prick my finger and create blood loss.
About a month ago I ordered I discovered the keto breath sensor KEYTO and have found since then that  it wonderfully simplifies  the process of being on a keto diet.
Keyto costs $99 and comes in a box the size of a video cassette  case.
In the box is the sensor device, four blowing mouthpieces, a very simple user manual, a AAA battery and a cute little bag for carrying the device
Ethan Weiss, MD, a highly respected preventative cardiologist and founder of Keyto includes a welcoming message for users which summarizes the mission of Keyto:

We designed the Keyto program to help you over-achieve your weight loss and health goals. With the Keyto Breath Sensor in this box, and the Keyto App on your phone, you have the key to unlocking success. You’ll be eating delicious foods, losing weight, and many  users even report an increase in energy and focus

Using Keyto Is Simple and Convenient

Getting started with Keyto is very easy: download the Keyto smartphone app, log in and follow the straightforward directions for pairing the breath sensor with the app.
Once paired via Bluetooth making measurements is easy. It’s important to understand the breathing technique needed and to facilitate this I strongly recommend watching the brief explanatory video Weiss has provided. Basically, you want to use a normal breath and blow for 10 seconds so that you are near the end of expiration when the device makes its recording.

To initiate a measurement you push the plus sign on the main “Journey” screen in the app then push the on button on the sensor.
Usually, if the sensor has been turned on and the app is activated the app immediately connects to the sensor, occasionally I have had to turn the sensor off and on again to initiated the connection.
At this point the sensor begins  warming up, reaching a temperature of 400 degrees Fahrenheit over a period of about 80 seconds.
The app displays the progress and offers you the option of answering some questions about how you are feeling and doing on the keto diet.
I often take my BP while this is going on. Sometimes I read the New Yorker. Frequently I listen to Radiohead (Climbing Up The Walls). It takes a while. Pay attention, though. You don’t want to miss your blowing window and have to repeat the process.
The app will give you a warning about 10 seconds prior to the time you need to blow. The graph to the right appears when it is time to blow and you can view the sensors output as it tracks the acetone it is seeing over the 10 seconds that you blow.
At the end of the blow you wait a few seconds, eagerly awaiting your score. Will you be in Ketosis?

Finally, your score is revealed. In this case I was congratulated for being in light ketosis with a fat burn of “medium high.” The highest score is an 8.
You can add notes to the record of your score
If you blow a 6 the app tells you that your fat burn is high and that you are in ketosis: “metabolizing fat like a champion.”

Accuracy of Keyto

When I first began using Keyto I checked the Keyto numbers versus the beta hydroxybutyrate (BOHB)  numbers I was simultaneously getting from my Keto-Mojo meter.
I found a Keyto 3 corresponded to 0.8 BOHB, a Keyto 4 to 0.9 BOHB, and a 5 to 1.0 BOHB.  That was enough to convince me that the device was accurate and useful in measuring my level of ketosis.
Given that it is so convenient compared to a finger stick I have stopped using the Keto-Mojo completely.
My observations confirm what Weiss and Ray Wu, MD, the cofounders of Keyto describe in very lucid prose here.

In extensive user testing, Keyto is directionally consistent with the more accurate commercially available blood meter. Keyto and blood β-hydroxybutyrate trend directionally the same in the majority of cases. Both go up and down in similar magnitude at different ranges of ketosis. There are some differences which are likely due to biology – the kinetics of clearance of acetone and β-hydroxybutyrate are not identical.
Some of the differences are also likely due to how we designed the Keyto program. Our primary goal was to develop a system that would give users the information they need to know i.e. if they are in ketosis, which would ultimately help promote healthy behavior change. Therefore, we chose not to report acetone concentrations in PPM or to attempt to convert PPM to blood β-hydroxybutyrate (mmol/L). The Keyto Level system was simply more effective, motivating, and fun without adding complexity and false precision.

I can make multiple measurements throughout the day without worrying about the cost or the discomfort of a finger stick. The ability to make multiple measurements means that I am getting very rapid and frequent feed back on how my dietary and lifestyle choices are effecting my level of ketosis.
Warning! Because the device is so convenient-literally you can have it with you at all times-you may find yourself blowing into it excessively. This may irritate your friends and loved ones, especially those that aren’t on a keto diet.

Keyto is Legitimate

The Keyto website has an excellent introduction to the keto diet (keto 101) and has numerous other very helpful resources for those who seek to lose weight using the diet.
In general I get a good feeling of integrity and legitimacy from every aspect of the Keyto operation.
I have a tremendous professional respect for Ethan Weiss, the cardiologist behind Keyto. He’s very active on Twitter and is typically spot on with his comments. He’s done a podcast with Peter Attia which serves as an excellent summary of atherosclerosis and coronary artery disease. He does really good basic science research involving growth hormone.
Weiss is now doing his own podcast called Best Known Method by Keyto which I highly recommend. It is not, surprisingly, focused on the keto diet or the keyto brand but interviews thought leaders in cardiology like Ron Krauss and Lisa Rosenbaum.
If you want to read more about how the Keyto breath sensor works see here. This is a very clear and concise description of the science behind the device and it is complete with references.
Ultimately, although I consider myself a keto-friendly cardiologist, I’m most interested in the diet that helps my patients achieve  and sustain their goals of weight loss and better health. For many this is the keto diet.
And for those who find the keto diet is optimal for their health I will be advising them to acquire a Keyto breath sensor and check out the programs Keyto offers to support their health goals.
Acetonely Yours,


10 thoughts on “I Am A Keto-Friendly Cardiologist And I Love Keyto”

  1. Dr. Pearson, after speaking with you yesterday about Keto and the progress I had with it, I ordered the Keyo monitor. I would be very willing to be a advocate patient in my progress. Of course, all my info would go through you first. I would be willing to have you monitor my progress, share my recipes or anything I could do to help spread the news about Keto. I have a lot of recipes, ideas and skills to help make this a successful journey for a lot of people that may be skeptical. Let me know. Thank you.

  2. Have you gone any further correlating Keyto numbers with BOHB, like all the way to 8? I think I read that the reading is not linear, and the Keyto folks are ridiculously cagey about that (why? what are they hiding?)
    I don’t own any other monitor, and it frustrates me to think I have to buy one just to make the comparison. Thanks!

  3. Rather than do a Keyto check, I suggest checking your resting heart rate. The AHA has just added RHR as a risk factor along with hypertension. The AHA recommends lowering both BP and RHR. Your rate pressure response should not be over 7800 while resting. So lower your heart rate naturally by running or other aerobic exercises such as rowing or swimming. A healthy resting heart rate should be closer to 50 bpm than 70 bpm. This will increase your heart rate reserve and help you achieve greater age adjusted VO2 MAX. The bottom line is that there is no lazy way to lower heart rate naturally and no lazy way to maximum age related heart health. Just do it!!!

    • Erwin,
      Can you provide a reference on AHA adding RHR as a risk factor?
      Measuring your level of ketosis, of course, is not an attempt to look at risk factors for heart disease but an aid in one dietary approach to weight loss and diabetes.
      Although lower heart rate is associated with better cardiovascular outcomes it is not clear that it causes those better outcomes.
      Aerobic exercise, on the other hand, improves outcomes and is associated with a lower heart rate and I think we can all agree that regular moderate aerobic exercise should be everyones goal independent of what it does to one’s heart rate.

    • My recommended version of the Med diet focuses on eliminating added sugars, processed foods and low nutrient value carb sources and increasing non-starchy vegetables, fish, olive oil and nuts. It naturally moves toward a lower carb, higher fat diet. This may help with weight loss and diabetes for many patients but for others something more drastic is needed. The keto diet adds more structure and a monitoring technique that ensures you are cutting carbs enough. If we carefully monitor lipoprotein response to the diet it can also be heart healthy. If it results in significant and sustained weight loss with reduction of BP and diabetes then it almost certainly will improve long term health.


Please leave your comments. The skeptical cardiologist loves feedback. He reads all and replies to all that warrant a reply.