The Best Way To Test For Ketosis & Track Your Blood Glucose.

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In past articles…

…including “The Ultimate Guide To Biohacking Your Blood Sugar Levels (And Why Sugar Sometimes Isn’t Bad).” and “5 Simple Steps You Can Take To Live Longer, Banish Blood Sugar Swings & Massively Enhance Energy Levels.” …

…I've highlighted the extreme importance of monitoring or somehow self-quantifying your blood glucose levels.

And in my article “How To Get Into Ketosis“, I discuss the importance of ketones and ketosis and how to get into a state of ketosis efficiently.

However, today, I'd like to discuss how to actually test whether or not your efforts to manage blood glucose or increase ketones are actually working!

How to Test Your Blood Glucose

While a single blood test using an inexpensive blood glucose meter like this from any drugstore or health website can give you a static, single snapshot of your blood glucose levels, nothing beats a continuous blood glucose monitor for truly determining how your diet is affecting one of the most important parameters of your health and fitness: glycemic variability.

A continuous glucose monitoring system (CGM) is a system that does just what it sounds like: it monitors your blood sugar continuously, 24 hours a day. The data is transmitted from a sensor which is inserted right beneath your skin, and this is attached to a transmitter which sends the data to the receiver. You are then able to see your blood sugar at any point via a receiver or a phone app.

For those of you who want to know the results of my own 24-7 blood glucose monitoring using my Dexcom G6, which is currently implanted on my right abdomen, you'll just have to wait, as I'm working on a report of the results. In the meantime, here's a fascinating read on what you can actually see when you monitor your blood glucose with a continuous blood glucose monitor.

The basic way any CGM system works is via a tiny sensor inserted under the skin of your abdomen or on the back or your arm that is typically worn for 7-14 days (in my opinion, if you are eating your normal diet, you eat the same things regularly, and you test for two weeks, you’ll know everything you need to know about your blood glucose and can likely stop testing at that point unless you’re wearing the CGM for medical reasons). This sensor will be reading glucose levels in the interstitial fluid below your skin’s surface and is attached to a transmitter which sends the glucose level data wirelessly to an insulin pump (if a diabetic is using the CGM) or other receiver or smartphone app.

This means that at any given time during the day or night, you can look at your device and see how your blood glucose level is trending, and even receive instant notifications if it gets too high or too low. Since CGM is measured over a range of time, such as over minutes or hours, one of the best values to pay attention to are your postprandial (post-meal) blood glucose levels. The ideal postprandial levels range from 78 mg/dl over two hours following the meal (in men) and 81 mg/dl over two hours following the meal (in women). A healthy fasting blood sugar that is normal for people without diabetes ranges from 70–99 mg/dl, although I personally try to keep my sugar below 80. Within two hours after a meal such as a large breakfast, lunch or dinner, levels should ideally be less than 140 mg/dl.

The two most popular CGMs – both of which I’ve experimented with and found to work well, especially when covered in kinesiotape or some kind of ace bandage for high-intensity workouts, races, swimming or sauna exposure – are the Dexcom Continuous Glucose Monitoring System and the Freestyle Libre. Admittedly, because of my highly active lifestyle, I was nervous about using a continuous blood glucose monitor due to my fears that it would constantly become detached from my body, become water damaged, or that the extremely small needle that is inserted between the CGM and the skin would become bent. But as long as I am careful to tape the CGM prior to intense physical activity, it seems to stay attached and continue to take good readings, especially the more expensive but far more accurate Dexcom G6 model. The SIMPATCH adhesive patch for Dexcom works particularly well for this.

Now don't get me wrong: owning a basic, cheapo blood glucose meter is a good idea, but if you can convince your physician to write you a prescription for a CGM (here's one guy's sneaky way to do it with an insulin overdose, which I do not recommend), it is well worth the insight you get. I personally didn't get insurance for my Dexcom and had to pay a few thousand dollars for an entire year of tracking, but the expense is worth it to me, because I'm getting a lifetime's worth of valuable data I can act upon to enable myself and many others to become healthier (yes, I invest in things like this instead of nice cars and fine China).

How To Test For Ketosis

In addition to blood glucose, it can be very insightful to measure your ketone levels, which are reflective of how efficiently you are burning fat, or how efficiently you are producing energy, even in the absence of high blood glucose levels.

Assuming you do not possess genes that would make you respond deleteriously to a high-fat, low-carb diet, ketosis can be a powerful nutrition approach to use switch your metabolism to prioritizing the use of fat as a fuel, while also increasing cognitive and physical performance (incidentally, even if you’re not achieving ketosis via a high-fat, low-carb diet, you can still amp up ketone production by intermittent fasting or engaging in other forms of calorie or carbohydrate restriction). Many people just assume that if they are “low carb” or fasting they are in ketosis, but it can be useful, especially if you’re just getting used to a new diet or supplement and trying to determine whether or not it increases ketone production. Ideal blood levels of ketones to indicate if you are in a state of ketosis range from at least 0.5 millimolar up 3.0 millimolar.

There are actually three testing methods for ketosis because there are three forms of ketones in your body: acetoacetate, acetate and beta-hydroxybutyrate, which can be tested in your urine, breath or blood, respectively.

Let’s begin with acetoacetate. The way ketones get into your urine is if they are “spilling over” in excessive amounts. This means that if there is an excess of ketones or if you are not actually utilizing your ketones efficiently, they can be dumped into your kidneys to be excreted in your urine as acetoacetate. The way to measure these excess amounts of ketones is through a urine strip, which changes colors relative to the number of ketones in your urine (usually the darker purple color on the strip, the more ketone bodies).

Unfortunately, this is not always a reliable test. Once your body is in a “keto-adapted” state and you’re burning ketones (including acetoacetate), you will see a progressively lower level of ketones that are reading on the strip. This is misleading since you may actually be in a deep state of ketosis but the strip says you have low ketones. In reality, there are just fewer ketones spilling over into your urine. So urine strips can be a cheap and effective testing method if you are just starting to get into ketosis, but aren’t a viable long-term or consistent test once you’ve been consistently in ketosis.

Acetone (also called acetate) is the second ketone body and is produced by gas exchange in your lungs. Acetone has been found in research to correlate very closely to levels of BHB in the blood and can be measured directly through the breath with use of a breath-measuring device.

One of the key advantages of a breath meter for testing ketones is that it is reusable and usually involves a one time purchase of a breath-measuring device such as a Ketonix, a Keyto or a LEVL.

Finally, the primary ketone body that you use for energy (or can take as an exogenous ketone supplement) is beta-hydroxybutyrate, or BHB. BHB enters the cell and is converted to acetylacetone, which can then be ultimately converted to acetyl COA and enter the Kreb’s cycle for production of ATP. A blood test for BHB can be done easily at home the same way individuals with diabetes check their blood glucose. You simply prick your finger, squeeze a drop of blood out of your finger, tap it on a strip and a small handheld reader will tell you the level of BHB in your blood. This is the most direct and accurate way to measure your level of ketosis. The downside to the blood ketone meters is that some people may have a strong aversion to needles and blood, and the testing strips are considerably expensive, usually $5-$10 per strip (although a newer device called “Keto Mojo” has dropped the price of ketone strips down to 99 cents per test). The blood level of BHB is measured in millimolar concentration, known as mmol. Studies have shown most optimal ranges of BHB levels for benefits of ketosis are between 0.5-3.0 mmol, although this varies based on activity levels, time in ketosis, fat-burning efficiency, etc.

So how do I personally test ketones? Although, as mentioned above, I wear a CGM (the Dexcom G6) to monitor my blood glucose, I’m not a fan of the hassle or expense of constantly measuring blood ketones. Instead, I use the device mentioned above, a LEVL, to monitor my breath ketones.

Here’s how it works…

…during ketosis, the body generates molecules called ketones, one of which, as described above, is acetone. Because of its small size, acetone can appear in your exhaled breath as an indicator of fat burning and can be relatively (although not precisely) accurate representation of your blood ketone values.

Clinical research has demonstrated a correlation between the amount of acetone detected in the breath, blood ketone values and body fat burned, giving a reliable indicator of ketosis fat loss. A breath ketone measuring device such as the LEVL is designed to detect trace amounts of acetone in your breath when your body is burning fat. You simply breathe into it, and your breath is captured then analyzed by LEVL’s nanosensor, providing you with an instant measurement of your body’s acetone concentration.

When you first shift into a lower carbohydrate intake, your body increases the amount of fat it uses for energy relative to the amount of carbohydrates, and your breath acetone concentration ramps up. This increase happens over the course of 3-7 days until you reach an elevated level of breath acetone. If your diet becomes high in calories or high in carbohydrates, your body will become less dependent on fat for energy. This will result in an acetone concentration reduction over the course of 1-2 days.

I prefer this method of breath measuring since it’s quick, easy and gives me a quick glance at my approximate level of ketosis. It does not measure blood mmol concentrations, but I still find it far easier and more convenient than blood testing for ketones. If I were to test blood, I'd prefer to use the KetoMojo, which is the most affordable solution.


That's it!

In summary, while an inexpensive blood glucose meter can do the trick for blood glucose monitoring, a CGM is a far better solution for actionable insight without the hassle of pricking your finger.

And for ketones, I prefer breath measurements, for the reasons stated above.

Do you have questions, thoughts or feedback for me about testing glucose or ketones? Leave your comments below and I will reply!

Ask Ben a Podcast Question

33 thoughts on “The Best Way To Test For Ketosis & Track Your Blood Glucose.

  1. Roxy says:

    In coordinating with my doctor I paid out of pocket for a freestyle libre as I hit many markers for prediabetes, but my insurance would not cover it.

    I understand the issues preventing those with diabetes from obtaining necessary treatment. However, concerns should be directed to your local law makers, not individuals seeking preventative care/data.

  2. Hi Ben, Thanks for all this information. I am interested in getting a CGM system. Since I do not have Type 1 or Type 2 Diabetes do you have any suggestions on how to go about getting a CGM system?

  3. Jarod King says:

    Interesting difference between Keto-Mojo and Dexcom G6. After waiting for the two hour G6 warm-up to complete, I was reading 79 mg/dL glucose, but keto-mojo showed 101 mg/dL. That’s quite a difference!

    1. Philip says:

      First, it is because they are measuring two different things. The dexcom measures the interstitial fluid in your adipose tissue. The a glucose meter, like the Keto Mojo, measures your blood glucose. Second, the dexcom takes a while to settle in. I’ve been wearing the G6 for over a year and the G5 before that. They always require a few calibrations before they settle in and work. Usually by the second day of the sensor they are settled in and working.

      A few other things for people reading this. The Dexcom app works; however, you are limited to 10 days per sensor. However, if you use the Xdrip app, you can extend this to 14 days. Also, if you are wanting to export the data to other places, xdrip makes this much easier than the dexcom app.

  4. Lisa says:

    Great idea! I tried to get my doctor to agree to order this for me because my FBG levels are consistently above 95 mg/dL. They completely refused. Not sure how the average person dealing with a broken “health” care system is supposed to get this BEFORE they become diabetic, but MDs don’t seem interested in helping. Any ideas appreciated. I live in a very medically conservative and tiny state where there are basically no “functional med” MDs.

    1. A fellow human being says:

      Just bite the bullet, and slowly, but surely, save for a unit, and stop depending on some piece o’ shmuck system.

    2. Sarah Lyn says:

      I found I get much better care paying out of pocket. If you are using insurance doctors get flagged for things that may be considered “unnecessary.” When I was dealing with extreme mystery fatigue the doctor really wasn’t willing to do the testing I wanted until I told him I wasn’t using insurance. He lit up and then we discussed all the relevant testing without a problem! This has occurred for me over and over again. Also, the discount for paying in cash is often better than the price of a co-pays with insurance. I think the good docs out there are just as frustrated as we are most of the time. Just use common sense and do research so you don’t pay for BS from a shady quack.

    3. Wendy Peterson says:

      I used coupon from Good and got 28 days of meters (2) for $67 cash without insurance at Walmart Neighborhood store!

  5. Nicole Weddige says:

    Hey Ben – love your podcast. Wanting to check if you have a promo code for Keyto. I’m assuming not since you have one for LEVL – but it looks to me as though that device is a monthly fee and I really just want the device.

    Thanks – seriously – keep doing what you do – your podcast has opened my eyes and looking into going back to my medical field beginnings but getting some functional medicine certifications. All the research is truly fascinating.

  6. Peter says:

    Now that Ben is wearing a continuous glucose monitor, do you have a more precise recommendation on when to take the “Kion Lean” supplement before the highest carb meal of the day? Ie 30 minutes before the meal? 5-10 minutes before? Immediately before the first bite?

    1. Take it right before you start eating

  7. Emily says:

    Oh my goodness, I cannot believe the negative posts I’m reading here. One need not to be diabetic to be interested in their own vitals and if they can afford to do so, they are entitled to do that and to share their experience. I don’t always agree with when Ben has to say on lot of things but such attacks are just unnecessary and ill informed. I’m doing finger pricks to test my glucose and ketones everyday and no, I’m not remotely diabetic. I’m just interested in optimising my health. How does that offend anyone?!

  8. Just wanted to say– I’m a T1D triathlete. I support anyone wearing a Dexcom if they can afford it. I think it’s really cool device. If non-diabetic people could see what a piece of pizza does to them, many wouldn’t eat pizza as much. I also wear a Libre because I swim a lot and, as you have probably discovered, bluetooth does not transmit through water. Have you also set up your Dexcom data to be viewable on a Garmin watch? I wrote an article about how to set it up and analyze the data.

  9. Mike Cahill says:

    Hey Ben,

    I think I saw that you switched from the Freestyle to the Dexcom. My question if this is true would be why did you?

    1. The dexcom is a really high quality CGM, that requires a prescription. It's more accurate, albeit more expensive… Freestyle is still solid

      1. Mike Cahill says:

        Thank you!

  10. Crystal says:

    Wow I can’t believe the negative comments! Keep doing the great work, Ben. Managing your blood glucose and knowing how your body responds to different foods by testing your post meal and fasting blood glucose is a genius way to quantify another important biomarker to optimize health, and possibly prevent insulin resistance and type II diabetes. My doctor agreed and gave me a prescription today for the freestyle libre. Spread the word! I wouldn’t have known about this if not for your great article.

  11. Robert Allen says:

    As much as I feel for anyone who suffers from Diabetes I am shocked at the responses I see here. Ben is just a guy that is sharing his experiences with people. I find that inspiring. If I were diabetic I would be getting angry with other people, doctors, our food system, government and corporations who set us up for this terrible disease in the first place. Ben is a guy that is taking matters into his own hands and taking responsibility for how his own health and wellness because he felt like shit and wanted to get better. I have been doing the same thing because of Ben and I have responded well to everything I have added to my protocol. It is because of people like Ben that I am feeling better than I have ever felt in my life.

    My advice to those who feel like crap and want to tear people down is this: Stop getting angry at funny nut job biohackers that are doing some really cool stuff and then sharing it, take some breaths and look for the things that these guys are saying that may inspire you to get better. Because these guys believe that you can get better and so do I. And if you still don’t like what you see and hear, move on and find people who resonate with you and inspire you. Life is hard enough without adding more negativity to the world. Good luck to all.

  12. Amy says:

    The negative posts above or shortsighted and absurd. Disease, health, and aging exist across spectrums and attempts to optimize should be respected. There is an epidemic in this country of insulin resistance, obesity and type two diabetes. Other diseases such as Alzheimer’s are increasingly thought to be very related to blood sugar control. As a physician, I predict that in the not-too-distant future CGMs will be utilized for all of these conditions and possibly even some kinds of cancer. Ben is using a tool, originally developed for type one diabetes, to understand his blood sugar variations and optimize his health and aging. Doing so does not mean that he is keeping the it out of the hands of some needy type one diabetic! If anything, he is raising awareness and promoting these companys products. Lighten up people.

  13. Donna D says:

    Thx Ben, I always appreciate your innovative and new ideas. Just so you know, you inspire many.

  14. Sam says:

    As someone with type one diabetes your use of this device to help your manscape makes me sick! You need to find something better to do with your life than encourage people to add unnecessary market demand for a medical device where it is not needed. I hope you at least donated your Dexcom to one of the thousands of people who need one but can’t afford or get insurance coverage for one.

    1. Donna D. says:

      He’s not even remotely addressing type 1 diabetes… move on, and go back to your doctor.

    2. Tom McNiff says:

      By increasing the sales of these machines, he will decrease the price. Simple economics for a non limited resource

  15. Tina R says:

    I am NOT a diabetic. I have Reactive Hypoglycemia and I wear a Dexcom G6. If I did not have this my Dexcom monitoring my sugar levels, I could die. People think these Dexcoms are only for diabetics. Before I got my Dexcom, I was pricking my fingers every 2 hours , around the clock. Why? On September 19,2018 I went to bed around 10pm. like usual. Shortly after be my fiance crawled into bed and cuddled up next to me. My side of the bed was SOAKED. He tried to wake me no asking me if I peed the bed. ( I have no recollection of the following) I woke up and started to take my jammies off, as they were drenched, suddenly my eyes rolled back into my head, I started seizing and then stopped breathing. My fiance got me breathing and called 911. I woke up to 6 male paramedics in my bedroom. ( That is NOt how THAT fantasy was suppose to play out LOL just kidding!) They checked my sugar, it was 30. They gave me 3 doses of sugar water & then I came to. I spent a week in the hospital to try and figure out all the what’s, why’s, and how comes to be told they don’t know. I was prescribed the typical glucose monitor, figer pricking thing. I was checking my sugar off & on. I started eating more frequently with smaller portions. Every night as I was going to bed, my sugar would plummet. My fiance was afraid to sleep when I was asleep because we didn’t know if I would code again in my sleep. I asked my Doctor for a Dexcom. He agreed. Insurance denied. And denied. And denied. Because I am the opposite of a diabetic and do not take insulin, the insurance company felt I had no need for one. So every night, everyday around the clock, my alarm would be set to check my sugar. And every night my sugar would plummet. A week before Christmas, the man & I are out Christmas shopping. I had no symptoms,no warning. I wake up in the back of an ambulance. I guess I passed out at the store. Thank goodness my fiance knew what to do. Once again I spend a few more nights in the hospital. Trying to get approved for this Dexcom. Again – DENIED. Why? Because they have never heard of anyone who wasn’t diabetic needing one. FINALLY after numerous doctor visits and pages upon pages of medical history, I was approved. This monitor has been a true lifesaver for me. It wakes me up during the night when my sugar drops. It has given my fiance & I peace of mind knowing we will be alarmed when my sugar drops so I can address the situation right then and there. I always carry Glucose tablets, juice boxes, crackers & peanut butter with me at all times for just in cases. The point of my rambling- I was reading the comments about this guy’s article. I just want to say that the Dexcom is NOT just for diabetics. It truly has been my lifesaver- literally.

    1. Flo Yap says:

      Amazing reading your response. I’m a Type II Diabetic, insulin resistance, reactive Hypoglycemic with mostly low drops. The lowest I’ve dropped is to 48 with no warning signs. My doctor wants mg blood sugar to be 85 and above. My recent A1C was 6.2 so I was put on Metiformin and insulin only if I’m 299 or higher. I range normally below 185 in the morning but I eat late to keep my blood sugar up there and stable otherwise I drop. I hate this because I’m damed if I do and damed if I don’t, ugh.

      This monitor sounds like a good thing for me as I’m normally low, but throwing my A1C off by the way I eat so late which strangely I’m not hungry until around 11am to 12 noon. If I eat breakfast my blood sugar spikes and drops and like I mentioned I don’t normal have the tell tale signs that it’s dropping. I used to prick my fingers 5 timesa day and because of that my feeling has lesson. Now my doctor tells me to only check twice a day and if mg sugar is low I don’t take the pill.

      Now with recent food allergies and sensitivities I’m even limited more on whay I can eat. I feel like I’m fighting a no win battle or even a stalemate battle. Most family members and friends question my eating but I’m damed if I dio eat this or that and damned if I don’t..

      1. Ron says:

        Getting a CGM was an excellent choice!

        It enables you to see exactly what your food is doing to you, and to test for yourself the opposing theories on diet and blood sugar.

        Reactive Hypoglycaemia is a precursor to type II diabetes. As counter intuitive as it may seem, reducing your intake of carbohydrates, especially refined carbohydrates, can reduce the swings in your blood glucose. Of course, you should only do this under the supervision of a competent doctor, who understands diet and diabetes.

        Jacqueline Eberstein, a registered nurse, very reluctantly took a job with a Dr Atkins. To her surprise she found that she had reactive hypoglycaemia, and the doctor that she had initially greatly distrusted managed to get her back to health. She has now been helping people for decades.

        This is Jacqueline Eberstein’s outline of the road to diabetes type II.

        The Road to Type 2 Diabetes

        What eventually leads to diabetes begins with insulin resistance of cells especially liver, fat and muscle cells. Insulin resistance means that cells are unable to respond to insulin properly. Even people with a normal weight based on BMI can have insulin resistance if they have a genetic susceptibility to diabetes.

        Here is the progression of insulin resistance to late stage type 2 diabetes as described by Dr. Robert Atkins.

        1. Insulin resistance of cells
        2. Insulin resistance with hyperinsulinism (the production of large amounts of insulin to control blood sugar levels)
        3. Insulin resistance with hyperinsulinism and ** reactive hypoglycemia ** ( unstable blood sugar)
        4. Insulin resistance and hyperinsulinism with impaired glucose tolerance (pre-diabetes)
        5. Type 2 diabetes with insulin resistance and high insulin production
        6. Type 2 diabetes with low or virtually no insulin production


        For Jacqueline Eberstein ‘s personal story read:

        For a list of the best doctors to treat blood sugar problems see:

        An alternative to your local doctor might be Virta, which is a company in the USA who helps US citizens treat their diabetes remotely.

        Virta have done some large studies over 1 and 2 years and published papers:

        I’m Australian, and have no link with any of the above. I’m lucky, I have an enlightened doctor, and know several others, a couple even in my home town, and I have been privileged to attend conferences with hundreds of excellent doctors and dieticians. Unfortunately, in my country, there are also thousands of doctors and dieticians who have no clue about diabetes and diet.

  16. Tiffany says:

    I hope and pray that your career goes to Crap. You are a twisted person. I wouldn’t want you coaching me or anybody else at that matter. What has our world come to? You need to really think about your CGM article and how twisted you sound. I thought I was going to read something knowledgeable I was wrong.

  17. donald scott says:

    Ben. Please ignore the negative comments above. Keep taking risks for knowledge and discovery. Enjoy the means you have earned any way you see fit. It is a shame that people view those who have with envy in stead of with possibility and grace.

    I for one value what you add to this world.

  18. Bonnie says:

    Seriously, are you even diabetic? My granddaughter is, and she has to test all the time. Seeing her give injections, and doing finger pokes breaks my heart for her. This post is ridiculous!

  19. Jm says:

    This is when you decide not to listen to this guy. You are encouraging people to commit insurance fraud. You should remove this post. It’s unethical.

    1. Jm says:

      And by the way…you are going to get somebody killed …why are you posting about “one guys sneaky way to do it with an insulin overdose” ….don’t care if you say you do not recommend it.
      You can DIE from low blood sugar people.

  20. Leah says:

    It’s a real eye roll to read about non diabetics using this technology when so many desperately need it to stay alive. There is nothing wrong with your blood sugar.

  21. Amie says:

    CGMs were develop to ease diabetes management and provide better glucose control in those WITH diabetes. A lot of individuals with the disease cannot afford this life changing and often saving technology, but how thoughtful of you to tout this as a fashion and health accessory. Your ignorance and lack of thought in this post amazes me. But hey, I’m glad that the CGM can help keep you from having to perform a few pesky finger sticks. For those of us who truly need the technology, it will continue to be a blessing even after you’ve moved on to the next health and diet fad.

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