optimal ketone and blood sugar levels for ketosis

  • A reduced carbohydrate diet will help reduce your blood sugars and increase your blood ketone levels.
  • Blood glucose control and improved metabolic health will help to reduce your risk of many of the diseases of modern civilisation such as diabetes, heart disease, stroke, cancer, Parkinson’s and Alzheimer’s.
  • We become ‘insulin resistant’ when our fat cells get full and can’t store any more energy.  Once our adipose tissue becomes insulin resistant, excess energy is stored in the liver, pancreas, heart, brain, eyes and other organs that are more insulin sensitive.  We also see increased levels of energy in our blood in the form of glucose, ketones and triglycerides.
  • Endogenous ketosis occurs when we eat less food than we need.  Our insulin and blood sugar levels decrease and ketones rise to supply the energy we need.  Exogenous ketosis occurs when we eat high levels of fat and/or take exogenous ketones.    While a low carb or ketogenic diet helps to stabilise blood sugars, most of the good things associated with ketosis occur due to endogenous ketosis  
  • If your goal is blood sugar control, longevity or weight loss then endogenous ketosis with lower blood sugars and lower ketones is likely a better place to be than driving high blood ketones with exogenous ketosis.
  • This article reviews blood ketone (BHB), breath ketone (acetone) and blood sugar data from a large number of people on a ketogenic diet to understand what “normal” and “optimal” ketone levels might look like.
Bonus: No time to read now? Get this post in PDF to save, reference, email to friends. Click here to get it free.

low carb diets reduce blood glucose levels

Many people start a low carb diet to manage their blood glucose levels, insulin resistance or diabetes.  As shown in the chart below, foods that contain less carbohydrate cause a smaller rise in our blood sugar levels.[1] [2] [3]

carbs vs gluocose score.png

If you are insulin resistant, have prediabetes, diabetes (Type 1 or Type 2) it makes sense to reduce the carbohydrates in your diet to the point where you can achieve the blood glucose levels of a metabolically healthy person.

If you cannot produce enough insulin to maintain your blood sugars it makes sense to reduce the insulin load of your diet to the point that your pancreas can keep up.

What are optimal blood sugar levels?

According to mainstream medical definitions:

  • “normal” blood sugar regulation is defined as having an HbA1c of less than 6.0%,
  • Prediabetes is diagnosed when you have an HbA1c between 6.0 and 6.4%, and
  • Type 2 diabetes is diagnosed when you have an HbA1c of greater than 6.4%.

However, as shown in the charts below, the mainstream definition of “normal” is far from optimal.



HbA1c vs cancer incidence

By the time you have “pre-diabetes”, you are at risk of many of the most common western diseases of ageing and causes of death such as heart disease, stroke, Parkinson’s, Alzheimer’s and cancer.[4] [5]


However, if you’re interested in optimal rather than what passes for normal, the table below shows some suggested HbA1c and average blood sugar targets.

risk level


average blood sugar









< 5.0

< 5.4

< 97


< 5.4

< 6.0

< 108


> 6.5

> 7.8

> 140

In this video, diabetes pioneer Dr Richard Bernstein tells how he refined his understanding of optimal blood sugar levels by asking healthy your sale reps to demonstrate their blood sugar metres on themselves.   They always seemed to come out at about 83 mg/dL (or 4.6mmol/L).  This correlates well with the level at which we see the lowest level of risk of various common diseases.  Today, people with Type 1 who follow Dr Bernstein’s recommendations balance their food and insulin to maintain a blood sugar of around 83 mg/dL or 4.6 mmol/L.

ketosis vs. hyperinsulinemia

While high glucose levels are bad news (due to glucose toxicity and excessive glycation) they typically go hand in hand with high insulin levels.[6] [7] [8]

A metabolically healthy person will store excess energy in their fat cells, ready for easy access when required later.  But if we continue to fill our fat cells with the excess energy they get to the point where they cannot continue to expand to absorb the excess energy.  It is at this point that our adipose tissue becomes insulin resistant.

Ted Naiman does an excellent job explaining insulin resistance in this video.  If you want to dig into the subtitles of this topic you should also check out:

The “good news” is that becoming insulin resistant will slow the expansion of your fat cells.  Unfortunately, the bad news is that once our fat cells become insulin resistant the excess energy will be re-directed to the parts of our body that are more insulin sensitive such as our liver, pancreas, heart, brain and other vital organs.

Our pancreas works overtime, secreting more insulin to try to keep the energy in the liver and fat cells in storages while we use up the glucose in our bloodstream.   High insulin levels mean that we will find it harder to release energy from our fat stores when we go without food.[9]

Without easy access to our body fat stores, we will be driven by our appetite to eat again sooner.  Without easy access to their fat stores, someone who is insulin resistant may be driven to eat more often.


Fasting insulin levels in healthy populations tend to range between 2 to 6 mIU/L.[10] [11] [12]  The average insulin levels in western populations are 8.6 mIU/L.   Meanwhile, the official reference range for “normal” fasting insulin is less than 25 mIU/L.[13] [14]  

Given that the western world is going through a crisis of metabolic health, it is safe to say that this cut off for ‘normal’ is also far from optimal.

how to manage your dietary insulin load

The good news is that you can tailor the insulin load of your diet to suit your current level of insulin resistance.   As shown in the chart below, the insulin generated by our pancreas is proportional the net carbs in our diet plus about half the protein it contains.

food insulin index vs carbohydrates fibre and protein.png

Reducing the insulin load of your diet can help to reduce your insulin and blood sugar levels to the point where your pancreas (and any insulin resistance you may have) can keep up and maintain normal blood sugars.  With lower insulin levels, we can access our body fat for fuel, either from our body or our food.

A person with type 1 diabetes is not able to produce enough insulin to keep energy tucked away in their liver, fat stores and even muscle tissue.  Without exogenous insulin, people with type 1 diabetes see both their blood glucose and blood ketones rise to very high levels.  This is called ketoacidosis which is dangerous and requires exogenous insulin as soon as possible.

As shown in the image below of JL, one of the first children with type 1 diabetes to receive insulin, people with type 1 diabetes quickly regain weight with exogenous insulin administration.


Rather than minimising insulin, it’s important to find the optimal dose of insulin.  Too much insulin can slow the release of fat from your body to be used for fuel.  Too little insulin and we effectively disintegrate.

People who switch to a low carb diet often find that their blood glucose and insulin levels drop and they are not hungry.  However, the problem with a very low insulin load dietary approach is that it may not contain enough of the vitamins and minerals that you need to help you avoid nutrient cravings in the long term.

2017-05-28 (7)

High-fat foods have a high energy density which can make it hard for some people to manage their satiety.  This can be problematic if their goal is weight loss.  Very high-fat foods also tend to be less nutrient dense and are less satiating than high fibre or high protein foods.

2017-05-28 (2)

The most ketogenic foods also contain lower levels of protein which is critical to managing satiety.

We need to find the right balance between a lower insulin load diet that will stabilise our blood sugar while still getting the essential nutrients that our mitochondria need to thrive and produce energy efficiently.

If you need help with the process of balancing your blood sugars and nutrient density, the Nutrient Optimiser is a tool to help you refine your diet to stabilised your blood sugar and insulin levels while also maximising nutrient density as much as possible.


blood glucose and ketones in fasting

When we go without food, our blood glucose levels decrease as the glucose in our bloodstream and liver (glycogen) are used up.  With less glucose available our body turns to our body fat stores.  Our liver converts our body fat to ketones for use in the brain rather than glucose.

This process is termed “endogenous ketosis” (endogenous = originating from within an organism).

2017-12-29 (4).png

As explained by Dr  Sinclair in this video, there are many of beneficial things that occur during endogenous ketosis such as autophagy, mitogenesis, mitophagy, upregulation of SIRT1 and increase of NAD+).  The body effectively goes into repair mode so it can make it through to reproduce in the next time of plenty.

The chart below shows my blood sugar and blood ketone (BHB) levels during a seven day fast.  As glucose levels decrease ketone levels rise to compensate for the lack of energy.


The sum of glucose and ketones continues to increase during fasting.  The sum of glucose and ketones can be thought of as the “total energy” (i.e. glucose + ketones).

Often in fasting, the body will let the total energy in the blood go quite high.  This high-energy state enables you to be at a very high state of alertness and be ready to find food to survive.

Exogenous ketosis vs endogenous ketosis

The mental clarity after a few days of fasting great!  But in practice, it’s hard to mimic all the benefits of going without food by forcing higher ketones with a very high-fat diet.

I think it’s important however to understand the difference between exogenous ketosis and endogenous ketosis.  

  • Endogenous ketosis is when we eat less and our body is forced to use some of our body fat to make up the difference. 
  • Exogenous ketosis occurs when we eat lots of fat (or take exogenous ketones), and we see blood ketones (beta-hydroxybutyrate) build up in the blood.  

2017-12-29 (5).png

Higher levels of ketones can build up in the blood when you are eating more fat than you are burning.  As a general rule, higher blood ketones are not a cause for concern as long as your blood glucose levels are also low (i.e. low total energy).

You will always be somewhere on the spectrum between exogenous and endogenous ketosis.  We need to ingest enough energy to not fade away and while building and repairing our organs and muscles.  

Keep in mind that most of the good things we attribute to ketosis and the ketogenic diet occurs due to endogenous ketosis when fat is coming from our body (e.g. autophagy, increase in SIRT1, increase in NAD+).  

What should your blood sugars and ketone levels be in ketosis?

Our understanding of the ketogenic diet is still evolving.  Keto Clarity co-author Eric Westman recently admitted that there is still a lack of clarity ideal ketone levels.[15]


The image below shows the ‘optimal ketone zone’ from Volek and Phinney’s Art and Science of Low Carb Living. which has unfortunately led to a lot of confusion.


In reality, it’s hard for most people to achieve “optimal ketone levels” (i.e. 1.5 to 3.0mmol/L) without fasting for a number of days or eating a LOT of additional dietary fat (which may be counterproductive if your goal is weight loss).

Recently, I had the privilege of having Steve Phinney (pictured below in our kitchen making his famous blue cheese dressing) stay with us when he spoke at a Low Carb Down Under event in Brisbane.


I quizzed Steve about the background to this optimal ketosis chart.  He said it was based on the blood ketone levels of participants in two studies.  One was with cyclists who had adapted to ketosis over a period of six weeks and another ketogenic weight loss study.  In both cases these ‘optimal ketone levels’ (i.e. between 1.5 to 3.0mmol/L) were observed in people who had recently transitioned into a state of nutritional ketosis (Capacity for moderate exercise in obese subjects after adaptation to a hypocaloric, ketogenic diet, Phinney, 1980).

Since the publication of this chart in the Art and Science books, Phinney has noted that well-trained athletes who are long-term fat adapted (e.g. the athletes in the FASTER study) actually show lower levels of ketones than might be expected.

Over time, many people, particularly metabolically healthy athletes, move beyond the ‘keto adoption’ phase and are able to utilise fat as fuel even more efficiently and their ketone levels reduce further.

Urine ketone strips are often considered to be of limited usefulness because the body stops excreting ketones as it learns to use them.


As our blood glucose levels decrease, our ketones increase to make up for the lack of fuel.   When we have less glucose available our insulin levels go down, more fat is burned, and blood ketone levels rise.  But it seems that over a longer period of time as our body learns to use blood ketones more effectively.


As discussed in this post, BHB ketones enable our body to store and transport ketones around the body before they are converted back to acetoacetate to be burned in the mitochondria.  Similar to high blood glucose levels, chronically high ketone levels are not necessarily a desirable thing.  As you will see below, a healthy metabolism tends to operate with less fuel mobilised in the bloodstream whether that be in the form of glucose, ketones or free fatty acids.

Crowdsourced ketone and glucose values

In late 2015 I pooled a range of data from myself and a number of people on the Optimal Ketogenic Living (OKL)  Facebook group.  After sharing this data initially, a number of other people sent me their data.  Later, Michel Lundell from Ketonix agreed to share an extensive set of anonymised data for me to analyse.

I hope that this crowd-sourced data will help to provide more clarity about optimal ketone levels in a similar way to Dr Bernstein surveying the glucose metre sales reps helped to provide a better understanding of what normal ketone values are.

The chart below shows the sum of the blood glucose and ketones (i.e. total energy) from nearly three thousand data points from a broad range of people following a low carb or ketogenic dietary approach.


On the right-hand side of the chart, we have a high energy situation from both glucose and ketones. While not as extreme, high energy situation is similar to someone with Type 1 diabetes with high glucose and high ketone levels due to inadequate insulin.  High levels of energy in the blood causes the pancreas to secrete insulin to hold the glycogen back in the liver and stop lipolysis (i.e. the release of fat from storage) until the energy in the bloodstream is used up.

On the left-hand side of the chart, we have a low energy situation.  These people do not have too much energy floating around in their bloodstream.  They are also likely insulin sensitive and can easily access their body fat stores for fuel.

As shown in my fasting ketone data above, we may see high blood ketone levels when we go without food for an extended period.  However, trying to replicate high ketone levels with high levels of exogenous ketones or an oversupply of dietary fat will not provide the same positive benefits as endogenous ketosis.

Based on this crowd-sourced data it seems the body tries to maintain a blood glucose level of around 4.9mmol/L and a blood ketone level (BHB) of around 1.5mmol/L.  The table below shows this data in terms of average as well as the 25th percentile and 75th percentile points.


ketones (mmol/L)

BG (mmol/L)

BG (mg/dL)




total energy (mmol/L)

























blood glucose and ketone levels during exogenous ketosis

Some people come to low carb or keto for therapeutic purposes (i.e. to manage chronic conditions such as cancer, epilepsy, traumatic brain injury or dementia).  These people can benefit from higher ketone levels to fuel the brain when glucose cannot be processed due to high levels of insulin resistance.  If you are trying to avoid cancer cachexia or trying to feed a child with epipepsy then an energy dense diet can be an advantage.  However, most people do not require this degree of therapeutic ketosis, particularly if weight loss or reversing insulin resistance is the priority.

People following a therapeutic ketogenic diet may be fuelling up with MCT oils to achieve high ketone levels and low glucose:ketone index values (GKI) value for therapeutic purposes.  Others will target high levels of ketones for brain performance.  Others will load up on exogenous ketones and glucose to ‘dual fuel’ the system for athletic performance.

One of the benefits of a low carb or keto diet is that it tends to eliminate a lot of hyper-palatable processed foods.  Stabilising blood sugar and insulin levels can also help normalise appetite and cause people to eat less.

The danger, however, with trying to drive high levels of ketones primarily through exogenous ketosis is that it will lead to an energy excess which will drive insulin and slow the use of fat and glucose stores until the energy in the bloodstream is used up.

Even though we are getting most of our energy from fat rather than carbs, the body will still work to bring maintain lower levels of energy in the bloodstream using insulin, and stop the release of stored glycogen and body fat until you have used up the energy in your blood from your food.  This is why Thomas Seyfried and Dominic D’Agostino talk specifically about the benefits of a calorie restricted ketogenic diet. [16] [17] [18]


blood glucose and ketone levels for weight loss and endogenous ketosis

Many people embark on a ketogenic dietary approach to manage their diabetes and achieve long-term weight loss.  They want lower insulin levels to enable them to burn more body fat for long-term insulin sensitivity and health.

On the left-hand side of the total energy chart below, we have a situation where we are generating endogenous ketosis, meaning that our own body fat is being burned for fuel.

With lower levels of energy in our blood, our body needs to draw on fat from our body fat stores as well as use excess stored fat and old proteins in our liver, pancreas, brain and other organs (i.e. autophagy).


To understand what all this means, the chart below shows the data divided into three thousand data points into five quintiles, from lowest to highest total energy.  For each quintile, I have calculated the average, 25th percentile and 75th percentile blood ketone (BHB) value.  Half of the ketone values fit between the 25th and 75th percentile values.

optimal ketosis


average BG (mmol/L)

BG (mg/dL)

ketones (mmol/L)

total energy (mmol/L)


































92 2.2




In the discussion above we see that the lowest risk of the modern diseases of ageing and metabolic health occurs when we have an HbA1c of less than 5%.   It seems that as a general rule (other than when we are fasting or aiming for therapeutic ketosis) being somewhere to the left of this chart is (in the first or second quintile) with blood glucose levels less than 5.0mmol/L (or 90mg/dL) is optimal.

In summary, it appears that the lowest blood sugar levels are associated with lower ketone levels and a lower total energy overall.  Or to put it another way, higher ketones are not an indicator of improved metabolic health.

Virta study ketone values

The crowd-sourced data above seems to also align well with ketone data from the Virta study (Phinney et al., 2017).

In this study, they aimed to get their patients into nutritional ketosis (which was defined as blood ketone levels between 0.5 and 3.0mmol/L as per the optimal ketone zone chart above) using a ketogenic diet.

The distribution of BHB levels is shown in the chart below.  The average blood ketone levels over the first 10 weeks of the study were 0.6mmol/L, with a standard deviation of 0.6mmol/L.  The chart below shows the distribution of blood ketone levels.

2017-12-29 (6).png

In spite of consuming a ketogenic diet under the supervision of Steve Phinney and the Virta team, many of the study participants did not achieve ketone levels that qualified as nutritional ketosis.  Although the ketone values were reasonably low, the reduction in HbA1c was still substantial.

Virta HbA1c.png

Many of the people on insulin were able to reduce or eliminate their insulin requirements.  Also, most of the participants lost a significant amount of weight.

2017-12-29 (10).png

Do ketone values change after long-term adaption?

Anecdotally it seems that people who are very physically fit may find they have lower blood ketone levels as well as lower blood sugar levels.

In fact, unless you are managing a chronic condition that benefits from high ketone levels (e.g. Alzheimer’s, Parkinson, dementia or epilepsy) you could save your money on testing ketones and focus on making sure your blood sugars are closer to optimal.

Anything ‘keto’ is very trendy at the moment, as discussed in this article, ketones



Is it the ketones or NAD+ that is really doing the good stuff?

A smart friend of mine, Robert Miller, has been challenging my thinking recently around ketones recently.   Robert’s theory is that the benefits that people attribute to ketones are actually mainly due to an increase in nicotinamide adenine dinucleotide (NAD+).[19] [20]


Adequate levels of NAD are critical to moving energy around our body, from our food to our mitochondria.[21]  NAD+ declines with age, increases in fasting, during a ketogenic diet or in response to exercise.  When NAD+ rises, SIRT1 helps our body to repair and improve our insulin resistance.[22]

Our NAD+/NADH balance is critical to controlling our appetite and telling the body whether we need more fuel, or if it’s time to tap into our body fat stores.


We can increase our circulating levels of NAD+ by eating a nutrient dense diet, particularly with adequate niacin (vitamin B3).[23]  There is a range of NAD+ supplements that seem to have positive benefits.

Nicotinamide Riboside is a close precursor to NAD+ which can be helpful for people who struggle to make NAD+ directly from food.

Image result for niacel

However, Nicotinic Acid (i.e. full flush niacin) is a much cheaper supplement that will work just as well for most people.

NAD+ metabolism is a fascinating rabbit hole if you want to do some research, but for now, let’s say that it’s essential to have adequate NAD+ to enable your mitochondria to convert the food you eat to energy rather than having it back up in your body.

What about breath ketones (acetone)?

You will likely be aware that three separate types of ketone bodies:

  1. acetone (breath ketones),
  2. acetoacetic acid, and
  3. beta-hydroxybutyric acid (BHB in the blood).


Fatty acids come to the liver either from our food or lipolysis (mobilisation of fat from our body) and converted to acetoacetate.   Unfortunately, we have no way to directly measure acetoacetate, only BHB in the blood and acetone in the breath.


The Ketonix is a device that you blow into that measures the acetone which is akin to exhaust that is released when you burn acetoacetate.


Blood ketones (BHB) are the most well-known form of ketone bodies.  There is some relationship between blood ketones and breath ketones, but it is not direct.  The chart below is Measuring Breath Acetone for Monitoring Fat Loss: Review (Anderson, 2015)[24] which states

“Endogenous acetone production is a by-product of the fat metabolism process… Breath acetone concentration (BrAc) has been shown to correlate with the rate of fat loss in healthy individuals…  A strong correlation exists between increased BrAce and the rate of fat loss.”  


The data below provided by Michele Lundell from Ketonix data shows a similar relationship between breath ketones and blood ketones but with a lot of scatter!


Breath acetone is likely a stronger marker of burning ketones for fuel, not just buffering energy in the blood.  A higher NAD+:NADH ratio means that less AcAc is stored as BHB and is available to be oxidised, at which point we see more breath acetone.

What I’m trying to illustrate with the dodgy clip art in the chart above is that having high blood ketones and low levels of breath acetone appear to be a sign that you are not burning the fat you’re eating.

By contrast, a high level of breath acetone with a low level of blood ketones (BHB) and low blood glucose may be a sign that you are very efficiently burning the fat you eat.

If you had a choice, I think it’s better to have high breath acetone (BrAce) and lower blood ketones (BHB) (which would suggest that you were efficient at burning fat) than high BHB and low BrAc (which would indicate that you were good at eating fat but not necessarily burning fat).

The figure below shows BHB vs BrAce for the different purposes that people nominate for using the Ketonix.  What we see is that people with diabetes (red trend line) have both higher blood glucose and higher blood ketone (BHB) levels (i.e. higher total energy).   Fuelling the mitochondria with the right nutrients that increase NAD+ will both help to burn off the excess energy and manage appetite through the NAD+: NADH ratio.


The second law of thermodynamics states that the total entropy (chaos) of an isolated system can only increase over time.  It seems that an organism that is ageing will decay and not be able it’s energy packed in storage, but instead, we will see increasing levels of energy floating around in the bloodstream (e.g. diabetes).

What can we use blood ketones for?

Blood glucose levels are likely more useful than worrying about blood ketones, I think tracking BHB can still be helpful in diabetes management.

You will remember that people with uncontrolled type 1 diabetes will have blood glucose and blood ketones that are sky high.  This is called ketoacidosis.

The mainstream approach to treating diabetes is by ramping up the insulin to suppress both blood glucose and blood ketones.  Unfortunately, without modification of diet to reduce the insulin load, excessive amounts of exogenous insulin will just slow fat burning as well as suppressing blood glucose levels.

Having low blood glucose and very low ketone levels (say less than 0.4 mmol/L) can just be a sign that you are taking too much exogenous insulin and need to back off the exogenous insulin dosing.  If you are taking exogenous insulin, this would be worth checking periodically to make sure you’re not overdoing the insulin.


  • Metabolic related diseases such as heart disease, cancer, stroke, diabetes, Alzheimer’s disease, kidney disease are the leading causes of death.
  • People with the best metabolic health (i.e. low HbA1c, insulin and blood sugar levels) have the lowest risk of dying from these common western diseases of ageing.
  • Keeping your processed and starchy carbohydrates low will help to keep your blood glucose and insulin levels and reduce your risk of obesity.
  • When we fast, our glucose levels decrease, and ketones increase to maintain our energy levels.
  • People who are metabolically healthy and insulin sensitive typically have a lower level of total energy (i.e. glucose + ketones) in their bloodstream.
  • We can mimic the rise in ketones with added fats or exogenous ketones that we see during fasting. However, the real benefits occur when the body is forced to draw on its own stored energy, and we experience autophagy, upregulation of SIRT1, and a rise in NAD+.
  • The benefits that we often attribute to ketones may also be due to increased NAD+ levels which occur in fasting and/or with a nutrient-dense diet.
  • We can only measure beta-hydroxybutyrate (in the blood) and acetone (in the breath). We can think the BHB as a buffer ready for use, and acetone as the exhaust showing that the ketones have been burned for fuel.  Higher levels of fat burning with a lower need for buffering is a better place to be than a large buffer in the blood and minimal fat burning.


[1] https://optimisingnutrition.com/2015/06/29/trends-outliers-insulin-and-protein/

[2] https://www.researchgate.net/profile/Peter_Petocz/publication/13872119_Holt_SHA_Brand_Miller_JC_Petocz_P_An_insulin_index_of_foods_the_insulin_demand_generated_by_1000-kJ_portions_of_common_foods_Am_J_Clin_Nutr_66_1264-1276/links/00b495189da41714fa000000.pdf/download?version=vs

[3] http://ses.library.usyd.edu.au/handle/2123/11945

[4] http://www.cardiab.com/content/12/1/164

[5] http://www.nejm.org/medicine-and-society-data-watch

[6] https://intensivedietarymanagement.com/tag/hormonal-obesity-theory/

[7] http://carbsanity.blogspot.com.au/2011/09/24hr-profiles-insulin-secretion.html

[8] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC329588/

[9] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC329589/

[10] http://wholehealthsource.blogspot.com.au/2009/12/whats-ideal-fasting-insulin-level.html

[11] https://www.ncbi.nlm.nih.gov/pubmed/11994907

[12] https://www.ncbi.nlm.nih.gov/pubmed/10535381

[13] http://emedicine.medscape.com/article/2089224-overview

[14] http://www.newhealthadvisor.com/Normal-Insulin-Levels.html

[15] https://www.facebook.com/AdaptYourLife/videos/vb.1608140252761871/1899686180273942/?type=2&theater

[16] http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0115147

[17] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1819381/

[18] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1819381/

[20] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2852209/

[21] http://www.ketoisland.com/blog/all-aboard-nad/

[22] https://selfhacked.com/2015/09/06/nad-and-sirt1-their-role-in-chronic-health-issues/

[23] http://mitofuel.co.za/mitofuel/

[24] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4737348/

[25] https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/s12986-015-0009-2

[26] http://care.diabetesjournals.org/content/24/2/362

[27] https://en.wikipedia.org/wiki/Homeostatic_model_assessment

[28] http://www.thebloodcode.com/homa-ir-calculator/


post last updated October 2017

  • Kathy says:

    Any thoughts on physiological insulin resistance for those doing ketogenic diets over the long term?

    I have been doing a ketgenic diet (565 days+) with all days having a blood ketone fasting level over 0.5 or greater with the average around 1.8. Over time the levels are reducing while fasting glucose is rising. I still test my fasting blood ketone as over 0.5 but it tends to range in the 0.8 to 1.3 range. I am careful with my tracking so my macros are always 80%+ fat with low protein and carbs.

    Just curious to anyone’s thoughts on this……

    Stats: Female/36 yrs/5’8/117 lbs

    • There are a number of possible issue here.

      This paper from Seyfried indicates that a ketogenic diet with excess calories can be an issue. If this was the issue then fasting or cutting back on total calories could be a consideration. It would be interesting to know if you were gaining weight as well as having rising blood sugars. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1819381/

      What about insulin levels? C-peptide? Is the pancreas burning out.

      I have also heard Peter Attia discuss this sort of thing but there isn’t much other detail about why a long term keto diet might not trigger insulin resistance.

      • Ash Simmonds says:

        “Excess calories”, but consider the source: KetoCal


        INGREDIENTS: Refined Vegetable Oils (Palm, Soy, Sunflower), Milk Protein (Casein, Whey), Soy Lecithin, Soy Fiber, Tricalcium Phosphate, Tripotassium Citrate, Arabic Gum, Inulin, Corn Syrup Solids, Sodium Chloride, Magnesium Acetate, Microcrystalline Cellulose, Calcium Chloride, Fructo-oligosaccharides, Corn Starch, Artificial Flavor, Calcium Lactate, L-Cystine, M. Alpina Oil*, C. Cohnii Oil**, Choline Bitartrate, L-Tryptophan, Sodium Caseinate (Milk), Silicon Dioxide, Potassium Chloride, Ferrous Sulfate, Sodium Ascorbate, LPhenylalanine, Natural Flavor, L-Valine, L-Tyrosine, L-Carnitine, Taurine, L-Ascorbic Acid, M-Inositol, Mono and Diglycerides, L-Histidine, Zinc Sulfate, Artificial Sweetener: Sucralose, DL-alpha Tocopheryl Acetate, Niacinamide, Calcium D-Pantothenate, Manganese Sulfate, Copper Sulfate, Thiamine Chloride Hydrochloride, Pyridoxine Hydrochloride, Riboflavin, Vitamin A Acetate, Folic Acid, Ascorbyl Palmitate, Mixed Tocopherols, Potassium Iodide, Chromium Chloride, Sodium Molybdate, Sodium Selenite, Phylloquinone, D-Biotin, Vitamin D3, Cyanocobalamin.

        Whilst they can be interesting, I really don’t like conclusions based on junk keto meal replacement stuff primarily based on processed ingredients and seed oils.

      • Noted Ash. Do you have any thoughts on why blood sugars might be drifting up while fat is at 80%. Personally I wonder if it might be better for long term health to run at higher levels of protein (with the proviso that your pancreas can keep up) to maximise nutrients.

      • Kathy says:

        Actually I have continued to lose weight my bmi is currently 17.6 so no weight gain and I eat at a caloric deficit, I weigh my food and track it carefully which is why I was curious about this specific phenomenon so that I look at any high correlations with changes in my glucose and ketone blood levels

      • Kathy, do you know if you get higher blood glucose levels with higher protein levels while keeping carbs low? There is heaps of useful nutrients in protein foods that would be good to maximise while keeping within the capacity of your pancreas to keep up. Have you don’t any matched ketone / glucose testing to know what your GKI number is? I would even be interested in adding your data points to this chart?

      • Kathy says:

        I stay on the super low end of the protein spectrum usually lower ranges for the therapeutic benefits of ketosis 30-45 g per day (under the 0.5 x lb/lean body mass).

        I have only increased my cals from fat when I went to under weight. Main sources of fat being mct oil, ghee, coconut oil, olive oil, avocado & avocado based products. I have started to consider keto supplements like ketocana but on the fence still.

      • Have you tried intermittent fasting to reset insulin sensitivity? Seems your insulin load is pretty low though so that’s unlikely to be a problem.

        I think it’s probably ideal for most to be at a higher protein intake to increase nutrients, though if you need the therapeutic benefits of keto that’s a whole different issue.

        I think the KeotoForce KetoCaNa is fascinating technology! I got the KetoCaNa in the mail the other day. I have tried it twice. Just a little seemed to kill my appetite for the day! My type 1 diabetic wife tried it and it gave her gut upsets (autoimmune – more sensitive). I’m looking forward to experimenting with it in the future.

      • Ash Simmonds says:

        Can’t seem to reply to your reply directly, dunno where this will end up in the stream…

        In the “keto science” communities we’ve come to a gentleman’s agreement to refer to it as adaptive glucose sparing as the term insulin resistance is too scary – much like many medicos and nutritionists are still freaked out by the term ketosis by conflating it with ketoacidosis.

        Eventually it’ll be more widely accepted the nature of insulin:glucagon ratios and such, and why protein can be insulinogenic and even raise blood sugar somewhat, but it’s not really an issue in sane amounts.

        I’m guessing you’ve been following the Unger stuff already.

      • Have seen a video by Unger on type 1. Interesting stuff.

        My main interest with protein being insulinogenic is for type 1 diabetics calculating their doses, but I think it’s relevant to some degree for type 2s who might benefit from moderate rather than high levels of protein to manage blood glucose levels.

        Is there any further keto science out there on blood glucose levels drifting up after a long period on strict keto? Jimmy Moore is another interesting case in point. I don’t think it’s a big deal if everything else is going along fine. It would seem to just be a way that your body decides to run at higher blood glucose levels?

      • Ash Simmonds says:

        Yeah I’ve been asking for more N=1’s from T1s with regard to protein intake for a while. From a purely observational standpoint it seems like mostly a non-issue. In T2s I don’t see how it could be an issue, if you’ve already got your carbs down to ketogenic levels the amount of protein you consume is never going to have any real effect on BG/insulin – relatively speaking. Some might benefit from an intervention period of a week or month of 4:1 keto, but for the most part cutting the carbs is going to do 90% of the work.

        There’s a fair bit of stuff out there regarding “physiological insulin resistance” and BG float. Again it’s something we’ve come to redefine as benign in the absence of exogenous carbohydrates at worst, and likely a beneficial trade-off in the long-term.

        As for Jimmy – I respect what the guy has done for the community overall, but I’m over the fascination and don’t really consider him an N=1 to follow. 3 years ago I wrote of my misgivings about him probably about to become “our” new ambassador: https://www.reddit.com/r/keto/comments/v2owk/after_8_years_as_a_lc_guru_jimmy_moore_finally/c50rxk1

      • I suppose my interest in the GNG issue was sparked by seeing a lot of type 1 diabetics struggling to manage their blood sugar response to protein.

        See this draft article for more on that – https://www.dropbox.com/s/1cl533l2dzb1dzy/Advanced%20dosing%20for%20type%201s.docx?dl=0

        Agree that the nutritional value from protein is highly desirable, but in the absence of exogenous medicating it seems to be a balancing act between maximising nutrition and overloading the system.

        Type 2s certainly seem to struggle to deal with protein more than healthy people. See https://optimisingnutrition.wordpress.com/2015/06/15/the-blood-glucose-glucagon-and-insulin-response-to-protein/

        It’s interesting to note that Metformin works by limiting GNG! http://www.nature.com/nature/journal/v510/n7506/full/nature13270.html

      • There’s not a lot written on PIR, however it usually refers to what happens when someone who is eating low carb then goes and has a significant amount of carbs and their blood glucose levels shoot up.

        This is not the case for Kathy as she is just continuing with her therapeutic keto diet.

        The issue could be pancreatic burn out which the c-peptide test would confirm.

        I also wonder if someone at extremely low protein (i.e. very low glucose) is not getting the nutrition they need and this can lead to other issues.

      • Kathy says:

        I plan on increasing protein a bit and tweaking a few other items (IF I have experimented with but didn’t find an impact on trend line; tried the true fast and tried the modified version with bulletproof coffee).

        I feel great health wise no issues with energy, mental clarity, sleep etc. (with some data & tracking ocd still lurking lol)

        Another interesting correlation I will throw out there to see if anyone else is quirky. When I travel for work (flying only car rides do not do this) my ketone levels sky rocket even as I increase water greatly I assume it has something to do with dehydration.

    • Paul Gansler says:

      I’ve just got a glucose meter. And I am still working my way through manual. Lol. But I think I should have got one that tests for ketones too. Although I read somewhere that you can get a good idea just from blood glucose. Oh and I’ve got pee strips. Which are showing deep purple. Do you think I can just track blood glucose or should I shell out for the ketone meter to get my ketone /glucose index
      Can’t wait till someone just makes an iPhone app to do this.

      • Ketones are interesting but I think is probably ideal to focus on get get your blood sugar down initially. The chart in this article will give you an idea of what your ketones might be.

  • DaveNox says:

    I think this a really useful development of your thoughts. I will certainly be using the GKI ratio myself, to see how I go. My recently started ketone tests seem to vary quite a bit: I don’t know if that is a common exoerience,

    I am a 62 yr old T2 DB in the UK, who is managing my diabetes with LCHF, fasting and HIIT exercise. I am a retired engineer (so I can make time available), and feel much more comfortable to work with some numbers that mean something to me. I have only recently started measuring ketones: the “ketone” label scared me off, until I educated myself. Last HbA1C was 5.1% (32) and my general wellbeing is transformed. As time goes on, I am looking much more at the wider health benefits of LCHF and a ketosis diet, and not just T2DB management.

    As a T2DB, I have often wondered what is the balance of my diabetes, between insulin resistance and low insulin production.

    One of the problems in the UK is that the tests available are fewer than in the USA. It is very difficult to get even one fasting insulin test, so something that is proximal is very useful.

    • Thanks Dave. Let us know how you go. I’m eager to add to this dataset as I think understanding the relationship between ketones and glucose is useful, even if just to save money on ketone testing.

  • Evincedl says:

    GREAT blog.
    What time of day are the ketone & glucose levels tested? Are these fasting (am) levels?
    I am in very similar situation as Kathy above.

    • Kathy says:

      Correct, I take my levels completely fasted in the morning so that mct oil and other ingested fats are not contributing to the blood ketone levels.

      My fasted state is usually 12 hours + with my last meal around 6 or 7 at night.

    • I was usually testing in the morning before food, but sometimes during the day too. I agree that it’s probably better to test in the morning for consistency without the food having an impact. Although I found typically my ketones increased through the day.

  • JW says:

    Thank you for the time you spend in putting together this information. Unrelated but the mention of Rosedale reminded of a question re exercise. Rosedale says you should exercise after meals to burn the excess, Keifer says resistance exercise before exercise is optimum for T2. Before or after, what do you think?

    • JW says:

      Oops sorry that should be Keifer exercise before eating..

    • Rosedale and Kiefer are pitching at two very different audiences. Depends if you are sick/diabetic/obese or bodybuilder/figure competitor. A lot of Kiefer’s stuff is about getting an insulin surge to build muscle after periods of extremely low insulin. Most people just need to drop some weight and reduce their overall insulin load.

  • JW says:

    I used to dismiss Kiefer as irrelevant to me ie for bodybuilding bros however if I look beyond that he is quite interesting, a lot of his research has been based on diabetic papers. Here https://www.youtube.com/watch?v=dXDEPc38y08 at point 33.50 mins he talks about resistance exercise before meals as being “life changing for T2s”.

  • I think the priority for type 2s would be to do some training. So whenever it works for you and feels good is probably the priority.

    Resistance training will burn through glycogen stores which are going to be full for most type 2s regardless of whether it’s before or after.

    For bodybuilders he’s saying to work out fasted and then eat afterwards to stop the ongoing breakdown of the muscles. Not as much of a priority if you’re not walking around most of the day with depleted glycogen.

    • Evinx says:

      If fasting insulin levels are low (say 3uIU/mL), how can you be certain it may not be bcs your pancreas is unable to secrete enough insulin to keep glucose levels in check (like with Kathy’s gradually increasing FBG numbers)? Is the only way to know is with C-Peptide test and/or GAD65?
      Would they be definitive?

      • Yeah. I’m not a doctor, but a c-peptide test seems logical to confirm that the pancreas is still functioning. If Kathy is using keto for therapeutic purposes (autoimmunity) it is possible that the same issue is also degrading her pancreas.

  • […] optimising nutrition, managing insulin – marty kendall […]

  • […] If you don’t have access to these tests another option is to test your ketones and blood glucose levels to establish the ratio of glucose to ketones, which can also help you estimate your insulin levels (see the glucose : ketone index). […]

  • Monica Perry says:

    Hi Marty,

    I got a question about your chart on Average glucose and ketones. Is that for fasting BS? Or average a day?

    Thanks 😉

  • Eric Leppert says:

    Hi I’ve just recently been on the ketogenic diet for about 6 months working with Dr. Fung because I have type 2 diabetes and not sure if I’m Keto adapted or not yet. This morning I tested my ketones and they were a 2.7 mmol and my blood glucose was a 6.0 mmol. Any thoughts as to why this is since I thought if ketones went up blood glucose should go down? Could it be that my body is still not Keto adapted?



  • Vivian says:

    Well look and you shall find. My fg was 90 ies with less than .5 ketone. A1c 5.7, so today i did glucose and ketone 2.5 hr after my lg meal. Glucose 84 (4.6) and ketone .7. With a GKI of about 6.6. Does this sound right, maybe im missing something, but I’m pretty sure im keto adapted. I need positive feedback, my A1c has got me bummed. Also, fg seens to be higher than evening glucose.

  • Tim says:

    Hi Marty.

    Keep up the good work I find your stuff very useful.
    My 2 cents on Glucose/Ketones.

    I have been restricting carbs for about 2 years now but have found it difficult to get ketones much above .5 mmol/l, even with glucose around 5 mmol/l. This was eating 1 or two meals a day and snacks.

    This changed dramatically when I went to 1 meal/day and fasting for 2 days/week. Ketones went to and stayed between 2-5 and glucose dropped further to about 4.6.

    Seems like a harsh regime but it actually isn’t. I never feel hungry weight is stable, I look forward to the fasting days as energy goes up and my mood elevates.

    We will see.
    Thanks for all your info.


    • That’s great. Sounds like you’ve found the ideal regime for you. Many people will need to incorporate fasting as well as a low carb / low insulin approach.

      • AQEEL says:

        im still learning about diet and fast relate to ketosis, can i know it is normal if glucose level 3.3 after 3 days of fasting. im just consuming water only in 3 days. it is extra supplement (magnesium and potassium) needed during my fasting ? i planning to do 21 days of fasting ( just consume water only)

  • […] glucose levels under control you could start to track your ketones or the glucose: ketone index (GKI).  Decreasing glucose along with rising ketones is a sign that your glycogen stores are being […]

  • […] ratio between glucose and ketones (GKI) can be a more useful measure when your blood glucose levels are reducing.  A reducing GKI is an […]

  • […] [4] http://optimisingnutrition.com/2015/07/20/the-glucose-ketone-relationship/ […]

  • […] you hear Seyfriend talk he seems very proud of and excited about the glucose : ketone index (GKI) which he developed as a proxy for a person’s insulin levels.  As you can see in the chart below, […]

  • […] just wanted to say thanks for your work on insulin load, food insulin index and glucose : ketone index.  It really helped me to understand what was holding me back from reaching and being able to […]

  • […] If you wanted to get more serious you could get a fasting insulin test, a HOMA-IR test, test your glucose : ketone ratio or get an oral glucose tolerance […]

  • […] If you wanted to get more serious you could get a fasting insulin test, a HOMA-IR test, test your glucose : ketone ratio or get an oral glucose tolerance […]

  • fatmummaslim says:

    Very interesting piece. I was directed here after increasong ketone levels. I eat a Low Carb High Fat diet, and do not fast as such. Some days I may naturally do intermittent fasting, just due to lack of hunger. My blood glucose levels have consistently been in the 3s, and my ketones are usually in the mid 2s at their lowest, but over the last few days have been in the 4s and even as high as 5.2.

  • Vivian Peters says:

    I am a bit concerned as my fasting is 76 and would not rise above 78 even after I eating and would remain between 76 and 78 all day unless I dont eat or if I eat a low fat meal. I have tried researching but I have not come accross a definitive answer as to why fasting/not eating would raise my blood sugar. I have been on the ketogenic diet for 2 months now and would like some advice.

    Vivian Peters

  • Charles Grashow says:

    FBG – 85
    A1C – 5.5%

    Is there a disconnect between the two numbers?

  • […] chart shows my glucose : ketone index (GKI) dropping to below 0.5 after a few […]

  • Sheila says:

    Hello Marty,
    I’ve been doing Keto since Sept. In the past month I have started IF – usually 24/1 eat lunch only with a tea for breakfast with a tb of coconut oil or MTC. I have no medical issues other than overweight. My BG is always around 3.4- 3.6 and ketones get as high as 7.1
    Is this ok?? I’ve asked this question on so many fb pages and no one seems to be able to answer me – I am hoping you will.
    Thank you so very much!!

    • Do you feel and look OK? That level of ketones would be of more of a concern if your BGs were high too. Seems your insulin levels are very low. If your insulin levels are too low then you may be losing muscle mass and too much weight. If this was as problem you could see how you feel with a bit more protein and green vegies.

  • […] table below shows the relationship between HbA1c, glucose, ketones and GKI.   Once you are getting good blood glucose levels you can start to focus more on nutrient density […]

  • Jessica says:

    I’ve been doing low carb for about 4 months now and I have lost over 70lbs. I’m pretty sure that I am/was insulin resistant. I have done two fast so far, one lasting 7 days and the other 4 days. I usually IF daily if I’m not doing a water fast. My question is, I saw a video by Dr. Jockers that stated that you’re not in NK with a bg of 80 and above. My fbg is usually 79-84 again unless I’m on the water fast. My bg is usually 65. Is a bg of 83-87 optimal for nk? What would the ketone be? I dont have a ketone meter.

    • The table above shows the relationship between Ketones and glucose. Sounds like you’re in a pretty great place. If you try to chase higher ketones with more dietary fat you may stall your fat loss. Glucose may come down a little but more with more fasting and weight loss.

  • brynstables says:

    Are you still wanting GKI numbers? I’ve been tracking the past 3 weeks and will continue for a while yet. Average seems about 5 which seems great but I’m T2D with NAFLD so must be IR?? Expected a higher number.

  • Charlene says:


    Please can people comment on the best time to test. I understand the best time in the morning fasted but not sure I understand why. Wouldn’t it be better to test after eating? And if so at what point?
    Thanks charlene

  • […] from the chart above to average blood glucose levels and the corresponding ketone levels and glucose : ketone index values.   I think this gives us a useful understanding of what different HbA1c risk levels look […]

  • […] From Optimising Nutrition […]

  • […] revisited the subject of the GKI (glucose ketone index) and went back to the original paper published in Nutrition & Metabolism in March of 2015 to […]

  • Jerry P Moore says:

    Marty I am a type 1 diabetic (25+years) and recently started measuring my ppm acetone every morning (ketostix). How do I use this information and what is it tell me about my LCHF diet?

    • Keeping minimal ketones in the urine mean you have adequate insulin on board so as not to be going into ketoacidosis. It’s more your blood sugars that will help guide your food choices.

  • […] The table below shows the the ketones corresponding to the different levels of metabolic health, HbA1c, blood ketones and the glucose : ketone index. […]

  • […] the end I think you should be consuming the most nutrient dense foods that will keep your blood sugars at normal healthy levels.   The food lists in the table below to suit your blood sugar levels and body weight […]

  • […] detailed in What are Optimal Ketone and Blood Sugar Levels in Ketosis it seems that lower levels of total energy (i.e. low blood glucose with some but not high levels of […]

  • Anthony says:

    Great post! Quick question…

    I was always under the impression that eating globs of fat would only prevent the body from burning it’s own fat but that it still wouldn’t affect insulin whatsoever.

    Are you saying that the production of ketones is not demand-driven but more so supply-driven, and that more fat consumed = more ketones in the blood = higher insulin response?

    Also, in regards to PSMF, would 0.8g/kg prevent LBM loss in the absence of carbs/fats, or is it necessary to raise protein?

  • Liv says:

    I am a female competitive athlete, (WBFF cat. Bikini) – last season I followed a typical prep with a coach defining my macros. High protein / mod. Carbs / low fat.
    I was happy with my results and placed 4th in my category. For the past months I have been on a keto protocol to rehabilitate my messed up metabolism thanks to the ridged dieting of a bodybuilding athlete.
    So far I am almost 3 months into a keto protocol and I love it.
    I’m still adapting, so lifting heavy is quite the challenge.. but I know that with improve once my brain has made the switch to burning ketones.
    Otherwise all the benefits of a keto protocol are enough to never want to go back to being a glucose burner.
    The lack of mental clarity, sugar cravings and inflammation was anightmare. I am thankfully free from all that. No more cravings, no more dependence on thermogenics or caffeine. I don’t even sip on BCAAS anymore.
    My keto macros are 80f/15p/5c – carbs coming from cruciferous vegs.
    I measure blood glucose and BHB with a monitor.

    My questions:
    1. I am having hard time finding legit information for FEMALE weightlifters and how to calculate adequate protein. (I’m tall )
    2. Is it possible to put on muscle mass on a keto protocol? (without “carb loading” – or taking glucose before a workout)

  • […] The well- formulated ketogenic diet approach is designed for someone who has very high blood sugars or requires therapeutic ketosis.  The diabetes and nutritional ketosis approach will be more nutritious and suit people looking to manage their diabetes.  Before too long, with the reduction of processed carbohydrates, your blood sugar levels will stabilise to more optimal levels. […]

  • My Hba1c went up on keto and physiologic IR is through the roof. Im eating no enriched carbs. My training and work is at play. Im confounded. Nearly 36 months LC, and 2 years SKD. Vision is blurry too. Told I was undereating? Yet IM slowly getting bigger. I gained 6lb muscle 5 lbs of fat trying CKD stuff (via DXA). Now Im strict. That said I feel really good. My body comp? Look like out of a movie. So I mention stuff isnt right but whats up? Finally got my nutrition almost 100% right. Soon Ill throw the data in the ON algorithm see where I add up… Love your site Marty. Legend

  • Don says:

    There is too much scatter in the glucose and insulin charts to be useful. From the glucose chart I would be better off eating an orange than an egg and in the insulin chart I could eat raisins or steak. In both there does not appear to be clear correlations.

  • […] insulin resistance or diabetes, then reducing your carbohydrate intake to the point you achieve normal blood glucose levels is a good idea,[22] both in terms of overall health and controlling appetite that can be driven by […]

  • […] the chart below, foods with less carbohydrate do in fact have a smaller impact on our blood sugar.[1] [2] […]

  • jan says:

    Marty, thanks for the excellent article. Though I’m bit puzzled about your statement: ” But keep in mind that most of the good things we attribute to ketosis and the ketogenic diet occurs due to endogenous ketosis when fat is coming from our body. ” OK, So if we are already healthy at our ideal body weight and ideal body fat, then ketogenic diet does not offer as much benefits since then we will not be restricting calories and all fat will be coming from outside? thanks

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