Ketosis & Measuring Ketones
All You Need To Know

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Following my recent post about carbohydrates, I've put together what I consider to be the most important facts about ketosis and measuring ketone bodies.

Ketosis vs. Ketoacidosis

Ketosis is a state in which your liver produces ketones at an accelerated rate, shifting the body's metabolism away from glucose and towards fat utilisation. The presence of ketones in your body, which is indicative of lipolysis, is a definite proof of ketosis. According to Volek and Phinney in their best-selling book "The Art and Science of Low-Carbohydrate Living", nutritional ketosis is defined by serum ketones ranging from 0.5 to 3.0 mM.

The frequently asked question is whether ketosis is dangerous. Ketosis is not only a great weight loss tool, but it has been used for treating or managing diseases such as epilepsy, Alzheimer's and even cancer. You can check out my post here to see more about health effects of ketogenic diets with links to relevant research.

While nutritional ketosis is perfectly safe, ketoacidosis is an indicator of serious health problems. Ketoacidosis occurs in serious health conditions such as type 1 and type 2 diabetics and alcoholics and has nothing to do with nutritional ketosis. The levels of ketones in ketoacidosis are 3-5 times higher than in ketosis resulting from a ketogenic diet.

Nutritional ketosis occurs when blood ketones are 0.5 to 3.0 mM. This is completely different to urinary ketones, as they may be higher or lower.

4 Ways to Measure Ketones

There are three types of ketone bodies: Acetone, Acetoacetate and Beta-Hydroxybutyrate (BHB). Unlike protein intake, where the daily amount is determined by your lean mass weight, the amount of carbs to enter ketosis can be estimated using:

1) Blood ketone meter

It's the most accurate way to measure BHB ketone bodies. The level of BHB in your bloodstream will tell you how much you have in your fuel tank but it will not measure the metabolic usage of ketones. Typically, this happens when you have started following the ketogenic diet and are not yet fully keto-adapted. Blood ketone meters can precisely determine the level of ketones in your blood but they are also pricey. To give you an idea, the meter itself is about $40 and the test strips cost $5 each. If you want to test yourself daily, it will cost you $150 per month plus the cost of the meter. I don't know about you but I'd rather spend it on quality food or a gym membership. On the other hand, if you are on the Restricted Ketogenic Diet and numbers matter to you, a blood ketone meter may be the best and only option you have.

Ketostix (urine test strips) vs. Blood ketone meter

2) Breath testing - "Breathalyzer"

According to Volek and Phinney in The Art and Science of Low-Carbohydrate Living (chapter 13, Ketones - To Measure or Not), a non-invasive and cheap alternative is to measure breath acetone concentration. Acetone is one of the ketone bodies that results from a break down of acetoacetate. The level of acetone will reflect the metabolic usage of ketones.

The Ketonix Acetone Breathalyzer is available and offers an easy and inexpensive way to test your breath ketones (acetone). Keep in mind that breath ketones do not always exactly correlate with blood ketones and are affected by several factors (alcohol consumption and water intake). You can find my review of the breathalyzer here.

3) Urine ketone strips

Ketostix, Uriscan and other urine detection strips are not as accurate. They only measure the level of acetoacetate - excess ketone bodies that are not utilised by the body and are excreted via urine. Urine ketone strips can still be useful during the initial phase of the ketogenic diet when you simply want to test the level of carbohydrates in order to enter ketosis.

Some people use them to test if they are sensitive to certain foods that may be keto-friendly but still have a negative effect on their progress. They are easy to use and fairly cheap. You'll pay about $10 for 50 strips, that's $6 a month if you test yourself daily. If urine detection strips don't work for you, use one of the other two methods.

4) Observation

Listening to your body's signals is another way of finding out whether you are in ketosis. When your body is in ketosis, you may  smell of acetone. This could be sensed in your breath, sweat or urine. Some people refer to this as ketogenic "fruity" smelling breath or "keto breath". If you detect any of these signs, you are more than likely in ketosis.

Why are Ketostix Inaccurate?

As mentioned above, although your body may produce ketone bodies which you can measure in your blood stream, Ketostix only show excess ketone bodies excreted via urine. These excess ketones are, in fact, wasted calories. Below are the main reasons for different level of ketone bodies in your blood and urine:

  • Ketostix don't measure all types of ketones produced by your body. Although there are 3 types of ketones (acetone, acetoacetate and beta-hydroxybutyrate), they only measure acetoacetate. Depending on how long you have been in ketosis, your body produces different types and amounts of ketones and you may not be able to detect acetoacetate when keto-adapted. For more details, check out this post at Ketopia.com.

  • As you become keto-adapted (3-4 weeks), you will excrete less ketone bodies via urine. This means that you may show high blood ketones and low or no urine ketones.

  • Also, changes in hydration affect the concentration of ketones. A high water intake may dilute the concentration of ketones in the urine. Because it's important to stay hydrated, you will likely see lower readings.

  • Other reasons (fluctuations that appear after waking up, after eating and post-workout)

More Ketones, More Fat Loss?

Most people believe that in order to lose as much fat as possible, they need to restrict their carbs intake as much as they can. I've already explained the main effects of a low-carb, ketogenic diet.

Currently, it's not clear what the full effect of such carbs restriction is. Some diet authors, including Atkins himself, supported the idea that more ketones equals more weight loss. The reasoning they gave was that ketones are, in fact, calories which are made from the breakdown of fat in the liver. Is that really a valid reason?

Ketosis & Measuring Ketones: All You Need To Know

Although some fat loss may appear as a result of a potential "metabolic advantage" (more ketones / calories excreted), the most important factor for fat loss is natural appetite control. While urinary ketone excretion means that calories are being lost, the effect is minimal: Based on recent studies, the  number of calories lost in the urine as ketones is not significant (100 kcal at most).

Anecdotally, higher levels of ketones may actually slow down fat loss. Individuals who maintain lower ketone levels (trace ketones) appear to lose fat more efficiently. Why does that happen? One explanation may be that high levels of ketones in the bloodstream may slightly raise insulin and block the release of free fatty acids from fat cells.

Also, when becoming keto-adapted, some individuals tolerate relatively greater carbohydrate intakes without disrupting ketosis. It's up to you to find your optimal carbs intake. As I've explained above, high ketone levels won't help you burn significantly more calories - no studies show such effects. As long as you stay in nutritional ketosis (0.5 to 3.0 mM), moderate amounts of carbohydrates can be added to your diet.

If you want to know more about ketone levels and their effect on fat loss, have a look at this post: Do Ketones Matter?

Don't Focus Just on Ketones, See the Big Picture

Recently, I've noticed a growing obsession when it comes to measuring ketones precisely. Although urine detection strips may not be accurate for keto-adapted people, they work for most of those that have just started the ketogenic diet. By the time they become keto-adapted, which takes 3-4 weeks, most of them understand what to eat and what to avoid without any real need to measure the precise level of ketone bodies.

Ketosis & Measuring Ketones: All You Need To Know

I've been in nutritional ketosis on and off for almost two years and can't really complain about urine strips. I don't personally need to track exact numbers because it won't make a difference to me. When I started, I used Ketostix to find out when I was in ketosis and what my net carbs limit should be. These days, my daily net carbs intake varies from 30 to 60 grams depending on how active I am.

My advice is that you should give Ketostix a try. If you need to keep track of your ketone levels, use a blood ketone meter or the breathalyser. In the end, what really matters is not ketones but the effects of low-carb diets: weight loss and improved health.

Tips for Measuring Ketones

  • Generally, ketone concentrations are lower in the morning and higher in the evening. Whatever time you pick to measure ketone levels, make sure to keep it consistent. Also, do not measure your ketone levels right after exercise. Ketone levels tend to be lower while your glucose levels are higher so you won't get representative numbers.

  • Keep in mind there are daily fluctuations caused by changes in hormone levels. Don't get discouraged!

  • Another aspect that affects the level of ketones is the amount of fat in your diet. Some of you may show higher concentration of ketones after a high-fat meal. Coconut oil contains MCTs that will help you boost ketones.

  • To easily increase your fat intake on a ketogenic diet, try fat bombs - snacks with at least 80% fat content.

  • Ketone levels tend to be higher after extensive aerobic exercise as your body depletes glycogen stores. Exercise may help you get into ketosis faster.

  • Ketogenic "fruity" breath is not pleasant for most people. To avoid this, drink a lot of water, mint tea and make sure you eat foods rich in electrolytes. Avoid too many chewing gums and mints, as it may put you out of ketosis; there may be hidden carbs affecting your blood sugar.

  • Increase your electrolyte intake, especially potassium. You are likely going to lose some sodium and potassium when switching to the keto diet.

  • Finally, if you find it hard to lose weight on a ketogenic diet, there may be plenty of other reasons than the level of ketone bodies: Not Losing Weight on Low-Carb Ketogenic Diet? Don’t Give Up and Read Further.

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Martina Slajerova
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Martina Slajerova

I changed the way I ate in 2011, when I was diagnosed with Hashimoto’s, an autoimmune disease that affects the thyroid. I had no energy, and I found it more and more difficult to maintain a healthy weight.

That’s when I decided to quit sugar, grains, and processed foods, and to start following a whole-foods-based ketogenic approach to food.

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Comments (253)

Can I take exogenous ketones while in ketosis? My Ketones is around 0.5 and 1.5.

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Hi Tony, to learn all about exogenous ketones check these out:
Exogenous Ketones - What You Need To Know
Ketones and Weight Loss: Do Ketone Levels Matter?
The Ketone Craze - Who Really Benefits From High Ketone Levels?

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Hi there,
I do not have diabetes however my ketone levels are 5.5. Should I be worried?

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Hi Reema, it is possible to achieve that level while fasting (this level is "starvation ketosis" which is far from ketoacidosis).

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I have been on the keto diet for 4 weeks. The 1st week lost 6#, week 2 gained 2 3rd week lost 1# and today nothing. I have been testing my blood ketos, week 1 was .06, week 2 was ,08, 3rd week 1.1 and today was 1.2. When should I start losing. I can't tell if I have bad breath and I swim for 1 hour every day. I weigh 161 and would like to lose 25-30# (I have 5'6" and 74 years old.
Help

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Please let me know who I can speak to regarding blood ketones 3-6
Type 2 diabetic no insulin a1c 6.2 so blood sugars under 108
On Keto 2 months
Any thoughts on high blood keto readings of 5 and 6?

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Hello Susan, you will need to speak to your doctor. Apart from the part that mentions the difference between ketosis and ketoacidosis, I'm afraid I can't give personalised advice.

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Hi Martina,
Can I ask you to let your followers know that buying serum ketone strips from their pharmacy can endanger the life of people living with type 1 diabetics??
I have a 10 year old daughter with type 1 diabetes. We need to test her serum ketones when she is unwell as she can slip into DKA very quickly.
On the weekend she became unwell and her ketones were climbing - we needed to test her ketones hourly and were quickly going through our supply of strips. My husband visited 5 local pharmacies in Geelong and they were all sold out. The pharmacist told my husband that many people are buying the strips for the keto diet and even the manufacturers cannot keep up with the demand.
Im not sure if you understand how dangerous it is for people with type 1 to have ketones and how incredibly important it is that we are able to determine the level of serum ketones..
Please think about this when giving out information about testing serum ketones. There are bigger things at stake here than weight loss!!!!!

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I'm sorry to hear that Lisa. However, as much as I understand your situation, it's not fair to blame people following the ketogenic diet. The pharmacies should be coping better with higher demands, especially since the ketogenic diet has been so popular for several years. People who follow a low-carb diet are the last ones to blame. In fact, this can happen with anything, including any medication and I'm shocked they haven't adjusted yet. There are people who follow the ketogenic diet to manage/help serious help conditions too - it's not just about weight loss.

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Martina, some nice detailed info here, I'll push my luck and ask a question.
I've been using my Ketone meter for one week now, and have been getting variable readings mostly from from 0. 4 to 0. 8. can you confirm that these numbers represent ketones produced from the fats I ate last meal, rather than my body's general ability to burn fat rather than glucose? I'm trying to understand the variability - I thought the aim would be to gradually to increase the reading.

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I have been on the keto diet for about a month, I'm very careful about what I eat and never go over my net carbs. I had been using urine strips and always tested over 40mg/dL. I just bought a blood meter and haven't got a result over .8 mmol/L, usually more around .4, I've done both test at the same time and the urine is always greater than 40mg/dL and the blood was only .4 mmol/L. Any ideas why, or am I confused on how I should be reading the results. I've had the energy increase along with the beginning of weight loss. Please help.

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Hi, i'm three weeks into keto diet and have just purchased a ketone blood monitor. My ketone reading is regularly sat at 0.9 what would you advice in order to raise this to the optimum 1.5?

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Hi Martina,
I’ve been following a low carb/keto lifestyle for 14 months now and I too have hashi, suffering chronic fatigue for around 15 years following my diagnosis. I’m the first to admit that I tend to cave one day at the weekend and have a ‘day’ off. However, after reading your article I’m realising I’ve probably never been in nutritional ketosis in the 14 months I’ve chosen this lifestyle!.This has been pretty soul destroying learning but it’s learning nonetheless. Regardless of nit being in NK, I most definitely feel 100% that I did however I’ve taken a holistic approached and changed many things such as supplements, Kefir and turmeric to name a few. Thanks for your article, just wanted to reach out after reading you have hashi too so it’s comforting to know that it helps. I’ll stick with it and need to try not to see food as a reward or a comfort and doing Keto has opened my eyes up to being an emotional eater. Thanks

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Hi, I have a question you may be able to help me with i started the keto diet about 7 days ago i tested myself with the keto strips the reading the last 2 days has been small 15 mg/dl am i in ketosis. I am 54 Years old 6-2 285.
Thank you,Sincerely Mike T.

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Hello,
Thank you for this article. I have been so frustrated with the blood keytone readings. I have been on Keto for a month. I really want the fat loss. My readings have never gone above .9  They range from .2 to .6 mostly. Do I need them to be higher?

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Hello. I am 67 years old. I keep my carb intake at or below 50 grams. I have eaten like this for years. Year before last, my fasting total cholesterol was I think 236, but triglycerides were low and HDL was high. It was the LDL that was off the mark. Well, this year my cholesterol was tested and it was 369. The doctor wanted to put me on meds but I refused. I knew it was from eating so much saturated fat. I love the fat on steak and pork like people enjoy ice cream and cake. I was eating it every day. I would eat the crispy chicken skin before eating chicken. I ate cheese and eggs, every morning, with sour cream...on and on. Anyway, I had to stop eating meat, eggs, cheese, dairy. I do not eat saturated fat, at all, now. I eat fish, egg whites, salad, tofu and up to 50 grams of carbs, which includes a small amount of beans, each day, and veggies. I also take vitamins and plant sterol supplements. I am wondering why my cholesterol went up so high when it was suppose to go down? No one in my family has high cholesterol, on either side. Not looking for personal advice. Just putting it out there.

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Hi.  Thanks for the great information.
I’m new on the diet; only a week.  My question is, if I observe my urine reading go down while my blood measure stays up, will that be indicative of adaptation?  The theory being that the Ketones still are being produced but expelled at a lower rate.
I anticipate adaptation to occurs within about a month and I hope at that point I feel better and have more energy.

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Hi Edward, yes, what you should observe as you are getting keto-adapted. But, keep in mind that very high levels of blood ketones can be indicative of poor keto-adaptation. When you get keto-adapted, your blood ketones will likely drop as well because you will be using them for fuel rather then keeping them in the blood stream: The Ketone Craze - Who Really Benefits From High Ketone Levels?

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Thank you for clarifying the "sweet" spot for Ketone levels for those of us in Nutritional Ketosis. I was very confused on how it related to ketoacidosis.
Extremely great reading. Thank you!

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Hello -
I started Keto about 7 weeks ago. I have been doing well and am about 15 lbs down (though I try to only weigh every 1-2 weeks so maybe a bit more at this point). I was using keto urine strips and getting large ketos results and decided to try a blood monitor. My result this morning (after 1 cup of coffee with HWC) was 6.4mmol/L! What?! Should I be worried? Should I add some carbs in to lower my numbers a bit. I find that I barely have an appetite these days and am only eating 1 meal a day and a couple of small snacks. I do not have diabetes. TIA!

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Hello Christy, although this level is high, it is in the starvation ketosis range, likely achieved by intermittent fasting combined with a very low-carb approach. It is far from the dangerous ketoacidosis level (extremely high ketones and blood sugar). However, achieving nutritional ketosis (0.5-3 mmol) would be a better approach as this is the optimal level for therapeutic purposes. You can read more about ketone levels in this post: The Ketone Craze - Who Really Benefits From High Ketone Levels?

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Hi Martina
I just wanted to say thank you, thank you for this amazing resource and the information you provide. It's amazing and [it seems] incredibly extensive.
I also have the app on my phone and have made a number of the recipes, some of which have become staples.  😊
Mianne

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Thank you for your kind feedback!

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I went to my urologist yesterday and my ketones were 0.0, so what is wrong with me? I just don't understand why I'm not in ketosis? I have been sticking to my macros as best I can. I don't have any special equipment to measure what I am eating but I try to eyeball it for now. Any suggestions? I was told to use the KISS method so I am doing just that, keeping it simple.

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Hi Ann, just to understand, is this number resprsenting urine ketone levels? Please, keep in mind that urine ketones are not a reliable way to asses whether you are /are not in ketosis, especially once you get keto-adapted. Also, make sure to read this post: The Ketone Craze - Who Really Benefits From High Ketone Levels?

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Hi, i meaured my blood ketosis value and is 0.7 mmol/l , how do I raise it to the optimal values of ketosis?

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Hi Tiziana, there are a few ways to raise your ketone levels (increase fat intake, fasting and exogenous ketones) but before you do, please, read this post: The Ketone Craze - Who Really Benefits From High Ketone Levels?
Facts:
1) Most people do not need to aim for high ketone levels.
2) High ketone readings (even blood ketones) may be indicative of your body not using ketones effectively.

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I am curious about my ketone readings.  i have done this before a few years back.  the past 3 months my ketone levels have been 1.5-2mmol/l at about any given time of day.  Nothing has changed in my diet and recently i am lucky to get .5-.9mmol/l.  Am i ketone adapted or did i somehow get knocked out of ketosis?

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Hi Jeff, do not get discouraged by lower ketone readings. It may just be that your body is using ketones effectively and you will naturally see lower readings. Please, read more here: The Ketone Craze - Who Really Benefits From High Ketone Levels?

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I am hitting my macros.. I test my blood ketones..0.4. What am I doing wrong.  Have
Been eating keto since Sept 2017. Before I started watching macros I was on point

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Hi Karen, see my comment above. I hope this helps!

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I found this article well written.
Still more science is to be understood on the body and metabolism. Your article was very balanced and not full of opinion.. Nice writing 😊

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I have a blood glucose meter it measure in mg/dl. I know I have to convert my numbers to mmol//l in order to get ketones.  my  numbers have been in the 80 to 90 range on the bgmeter. according to everything i have read, you need to divide 80 by 18 to get your ketone numbers.  which comes up to 4.4 in mmol.
which according to articles is over the range of .05 to 1.3  so how do I get lower?

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Hi Gary, just to clarify, you do use different strips for ketone levels? Most blood glucose meters will enable you to measure both ketones and glucose but you do need to use different testing strips to do that. This sounds like you are converting your glucose readings from mg/dL to mmol/L.

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I've been doing Keto for only a little over a month now, but my cholesterol has dropped nearly 20pts.  My triglycerides are down 15pts, my LDLs are down 14pts and my blood pressure is down from 130/90 to 122/72.  I've also lost 14lbs.  I have a concern though, I eat pretty clean and try and keep my carbs under 20g per day.  I test my Keto levels by blood test daily and I hang around 0.4 to 0.7.  Any thoughts on how to get those numbers up?

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Hi Jeff, I think you are doing great! It looks like you are keto-adapted, thus see lower readings: The Ketone Craze - Who Really Benefits From High Ketone Levels?
I rarely go over 1.5 mmol unless I've fasted for 18+ hours, mostly around 0.5-1 mmol.

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Hi
I am in my week 8 of keto.So far i have been very strict and trying to work out my macros to the T. I am drinking 4-5 liters of water everday without fail. But My ketostix always  show urine ketones level between moderate to large(40-80). What am i doing wrong here? And of course the weight loss is slow. What should i do?

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Hi Tanu, please, keep in mind that urine ketones are not a reliable way to asses whether you are /are not in ketosis, especially once you get keto-adapted. Also, make sure to read this post: The Ketone Craze - Who Really Benefits From High Ketone Levels?

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I have been on keto for about 18 months, my room mate started a month ago and I started testing with Keto Mojo blood tester.  My readings keep coming up Lo - the company says my ketones are too low to read - what can I do to make the higher to get into ketosis?  My room mates read fine.
Thanks -

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Hi George, do not get discouraged by lower ketone readings. It may just be that your body is using ketones effectively and you will naturally see lower readings. Please, read more here: The Ketone Craze - Who Really Benefits From High Ketone Levels?
There are ways to boost ketones (eg fasting, higher fat intake or exogenous ketones) but most people do not need to do that as they do not benefit from very high ketone levels.

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