optimal ketone and blood sugar levels for ketosis

  • Reducing the processed carbohydrate in your diet will stabilise your blood sugars and promote ketosis.
  • Elevated blood glucose levels are associated with an increased risk of many modern metabolic diseases such as diabetes, heart disease, stroke, cancer, Parkinson’s and Alzheimer’s.  
  • Insulin controls the release of both glucose and ketones into your bloodstream.  
  • You become ‘insulin resistant’ when your fat cells become full and no longer store excess energy efficiently.   
  • When your adipose tissue fills beyond your Personal Fat Threshold, excess energy is stored in places that are still insulin sensitive (like your liver, pancreas, heart, brain and eyes) and excess energy overflows into your bloodstream as elevated glucose, triglycerides and ketones.
  • Exogenous ketosis occurs when you consume extra fat or exogenous ketone supplements to raise the level of ketones in your blood.    
  • Endogenous ketosis occurs when you consume less food, insulin and blood sugars decrease and ketone production from your body fat increases.   
  • While a low carb or ketogenic diet will help to stabilise your blood sugars, the vast majority of the benefits of ketosis occur due to endogenous ketosis.
  • Reducing your intake of processed carbohydrates will help you to avoid hyperpalatable junk food which will improve satiety and helps you to eat less and lose weight sustainably with less effort.  However, reducing your carbohydrate intake to very low levels is not necessarily better.  There is nothing magical about having a particular blood ketone value, ketosis or a high fat ‘ketogenic diet’ that will cause you to lose weight more quickly.  

Low-carb diets reduce blood glucose levels

Many people follow a lower carbohydrate diet to manage their blood glucose levels.   Foods that contain less carbohydrate cause a smaller rise in blood sugar.[1] [2] [3]   If you have prediabetes or diabetes, it makes a lot of sense to reduce your intake of carbohydrates to drain the glucose from your bloodstream.

What are optimal blood sugar levels?

According to mainstream medical definitions:

  • “normal” blood sugar is defined as having an HbA1c of less than 6.0%,
  • Prediabetesoccurs when you have an HbA1c between 6.0 and 6.4%, and
  • Type 2 diabetes is diagnosed when you have an HbA1c of 6.5% or above.

However, these mainstream definitions of “normal” are far from optimal!  Your risk of diabetes, stroke, heart disease, cardiovascular disease and cancer increase with a HbA1c above 5.0%.   

By the time you have “prediabetes”, you have an increased risk of many of the most common western diseases of ageing (such as diabetes, heart disease, stroke and cardiovascular disease).[4] [5]  

If you’re interested in pursuing optimal rather than “normal”, the table below shows some suggested HbA1c and blood sugar targets based on the risk categories in the charts above.


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

A metabolically healthy person will store excess energy in their fat cells for later use.  But eventually, you get to the point your fat stores cannot continue to expand and absorb more energy from your diet.  

Once you exceed your Personal Fat Threshold, you become “insulin resistant”, and it takes more and more insulin to store and hold energy in your fat cells.

As you become insulin resistant expansion of your fat cells slows.  Your pancreas cannot produce enough insulin to jam the excess energy from your diet into your fat stores.  

Unfortunately, a reduced ability to increase your body fat is not as good as it might sound at first.  Once your fat cells are full, any excess energy will be redirected to other parts of your body that are still relatively insulin sensitive (i.e. your liver, pancreas, heart, brain and other vital organs).  

Your pancreas has to work overtime, secreting more and more insulin to hold back your stored energy while you use up the energy in your bloodstream that continues to be topped up from the food coming in via your mouth.

How to manage your dietary insulin load

The good news is that you can tailor the insulin load of your diet to help you stabilise your blood sugars.  Managing your insulin load can be particularly useful if you are injecting insulin to control your blood sugars as it is almost impossible to match large bolus doses of insulin with large amounts of dietary carbohydrates.  

A person with type 1 diabetes cannot produce enough insulin to keep energy locked away in their liver and fat stores.   Without exogenous insulin, someone with type 1 diabetes will see both their blood glucose and blood ketone levels rise as their stored energy leaches into their bloodstream.  

As shown in the image of “JL” below, one of the first children with type 1 diabetes to receive insulin, people with type 1 diabetes quickly regain weight with exogenous insulin injections.   Exogenous insulin works very well to switch off the release of stored energy.  


If you are injecting insulin, you need to think in terms of finding the optimal dose of insulin required to keep your blood sugars stable.  

  • Too much insulin can slow the release of fat from your body to be used for fuel.  
  • Too little insulin and you effectively disintegrate, with all your stored energy pouring into your bloodstream

Where this insulin-centric view of diabetes management and obesity falls down is that it doesn’t translate to someone who is not injecting insulin.

Your pancreas will not secrete more insulin than it needs to hold back your fat in storage while your body uses up the energy coming in from your mouth.   

Your glucose has to be burned off before your dietary fat or body fat.  A low-carbohydrate diet helps to stabilise your blood sugars.  However, in the long run, if you want to lower your blood sugar and reverse your diabetes, you need to find to eat that keeps you satisfied while also getting the nutrients you need.  

Endogenous ketones

When you go without food, the glucose stored in your bloodstream, liver and muscles (glycogen) is reduced.  

Once excess glucose is used up, your body will turn to your body fat stores for fuel.  Your liver then converts body fat to ketones to use as an alternative fuel for use by the brain, heart and other vital organs.  

This process is known as “endogenous ketosis” (note: endogenous means that the ketones originate from inside your body).

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Most of the beneficial things that we ascribe to the ketogenic diet occur during endogenous ketosis (i.e. autophagy, mitogenesis, mitophagy, upregulation of SIRT1 and increase of NAD+).  Your body goes into repair mode to make sure it can survive to make babies another day when food is more available.

The chart below shows my blood sugar and blood ketone (BHB) levels during a seven day fast.  As glucose levels decrease, blood ketone levels rise to compensate for the lack of energy coming in from your diet.  The sum of glucose and ketones can be thought of as the “total energy” (i.e. glucose + ketones = total energy).


When fasting, your body may allow the total energy in your bloodstream to reach quite high levels.  This enables you to be ready at a moment’s notice to hunt or gather food to survive.   However, unfortunately, we can not mimic the benefits of energy restriction by adding extra fat or exogenous ketone supplements to drive our blood ketones higher.  

As with any source of energy, your pancreas will raise insulin to manage your blood sugars and ketone levels and keep your body fat in storage while you clear the food coming in from your diet.

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

Our understanding of the ketogenic diet is evolving quickly as “keto” is growing in popularity.  

However, there is still a lot of confusion around what constitutes optimal ketone levels.  


It’s hard for most people to achieve and maintain “optimal ketone levels” (i.e. 1.5 to 3.0mmol/L according to this chart from The Art and Science of Low Carbohydrate Performance) without fasting or eating a LOT of extra refined fat.  


Unfortunately, consuming a lot more fat is typically counterproductive over the long term if your goal is weight loss or diabetes management.  Before too long you’ll probably find yourself putting on extra body fat which in turn will lead to higher basal insulin levels and higher blood sugar levels.

I had the privilege of having Dr Steve Phinney (pictured below in our kitchen making his famous blue cheese dressing) stay with us recently when he spoke at a Low Carb Down Under event in Brisbane.  During this time I quizzed him about the background to this optimal ketosis chart.  

Steve said the optimal ketosis chart is based on the blood ketone levels of participants in two studies done in the 1980s.  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 3.0 mmol/L) were observed in people who had recently transitioned into a state of nutritional ketosis.


However, while the ‘optimal ketone chart’ is based on people in the process of adapting to a higher fat ketogenic diet, over the long term, many people find that their blood ketone levels continue to decrease.   

Keto Clarity author Jimmy Moore even recently statues that elevated ketones will not necessarily lead to weight loss and that there is limited use in tracking them!  

Do we get better at using ketones?

Urine ketone strips (which measure acetoacetate in the urine) are considered by many to be of limited use because the body stops excreting ketones into the urine as it learns to actually use them rather than wasting them.   

It seems that your body adapts to use blood ketones more efficiently the longer you follow a lower carbohydrate diet.


Over time, most people move beyond the ‘keto adaption’ phase as their bodies learn to use fat more efficiently, and their ketone levels reduce further.  

BHB ketones are the storage and transport form of ketones that allow ketones to move around your body.  Your body converts BHB back to acetoacetate to be used for energy.

The BHB ketones that you measure in your bloodstream simply tells you how much energy you have stored as ketones in your bloodstream.  Unfortunately, our level of BHB in your bloodstream doesn’t tell you anything useful about your ability to burn fat for fuel. High blood ketones may just mean that you have excessive levels of unused fuel backing up in your bloodstream.  

Similar to high blood glucose levels, chronically high blood ketone levels are not necessarily a good thing.  A healthy metabolism operates efficiently with less fuel needing to be mobilised in the bloodstream (whether in the form of glucose, ketones or triglycerides).  

Just like a fuel-efficient car doesn’t need a massive fuel tank, you don’t need high levels of ketones or glucose in your bloodstream if you have a more efficient metabolism.

Crowdsourced ketone and glucose values

After still being confused after reading everything I could and ending up a lot fatter after pursuing ‘optimal’ ketone levels’ (greater than 0.5 mmol/L), I decided to compile some data from myself and some friend who were also tracking their blood sugar and ketones levels.  I wanted to understand what ketone levels looked like in people who had been following a reduced carbohydrate diet for a long time. Once I shared this initial data, other people sent me their data to add to the chart.  Later, Michel Lundell from Ketonix shared an extensive set of anonymised data.   

The resulting 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.  Blood ketones are shown in blue while glucose is shown in orange on the top.


On the right-hand side of the chart, we have a high energy state where both glucose and ketones are elevated.   While not as dangerous, this high energy situation is similar to someone with Type 1 diabetes with high glucose and high ketone levels due to inadequate insulin.  

On the left-hand side of the chart, we have a lower total energy state.  It seems that because they burn fuel efficiently, these metabolically healthy people don’t need large amounts of fuel circulating in their bloodstream.

Based on the analysis of this crowd-sourced data it seems the average blood glucose value for someone on a low-carb diet is around 4.9mmol/L (or 88 mmol/L) with a blood ketone level (BHB) of about 1.5 mmol/L.  

The table below shows this data in terms of average as well as the 25th percentile and 75th percentile points (along with corresponding HBA1c, glucose:ketone index (GKI) and breath acetone values).

ketones (mmol/L)BG (mmol/L)BG (mg/dL)HbA1cGKIBrActotal 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 may 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 muscle wastage that occurs in cancer cachexia or trying to feed a growing child who has epilepsy an energy-dense high fat diet can be an advantage.  However, most people do not require this degree of therapeutic ketosis, particularly if weight loss or blood sugar control is the highest priority.

People following a therapeutic ketogenic diet may choose to load up with MCT oils and other added fats to achieve high ketone levels and low glucose:ketone index values (GKI) values.  Others target high levels of ketones for brain performance.  Others load up on exogenous ketones and glucose together to ‘dual fuel’ for elite athletic performance.  

This over-fuelled state with elevated glucose and ketones is shown in the chart below from the people with the highest total energy.  


However, while it may be useful if you’re about to race in the Tour de France, chronically elevated energy from glucose and ketones is not ideal, especially if you are sedentary, trying to lose weight or improve your blood sugar control.

One of the benefits of a low-carb diet is that it tends to eliminate hyper-palatable processed foods that are typically a combination of refined starches and vegetable oils.  The mixture of refined starch and vegetable oils tends to be very easy to over consume.

The danger, however, with trying to drive high levels of ketones by eating more fat is that it will lead to an energy excess intake which will drive up insulin and promote fat storage.  

As shown in the chart below from our satiety analysis, reducing your carbohydrate intake can help you to avoid carb+fat hyperpalatable junk food, increase satiety, help you to eat less and eventually lose weight.  However, pushing carbohydrates to very low levels can lead to lower satiety and increased energy intake.

So while reducing carbohydrates is beneficial if it moves you away from hyperpalatable processed foods that are a combination of carb+fat, too much dietary fat will not be optimal if it leads you to significantly increased energy intake.  

Blood glucose and ketone levels for weight loss and endogenous ketosis

Many people embark on a ketogenic diet in the hope of managing their diabetes and lose weight.  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 endogenous ketosis (meaning that your own body fat is being burned for fuel).  With lower levels of energy in your blood, your body will draw on your body fat stores to make up the difference, as well as use excess stored fat and old proteins in your liver, pancreas, brain and other organs (i.e. autophagy).  This is a great place to be if you are trying to reduce your blood sugar or lose body fat.


What are normal ranges for blood glucose and blood ketones?

The chart below shows the data divided five quintiles, from lowest to the highest total energy.  

optimal ketosis

For each quintile, I have calculated the average, 25th percentile and 75th percentile blood ketone (BHB) value (i.e. half the values fit between the 25th and 75th percentile).

If you are on a ketogenic diet and relatively metabolically healthy, you may see BHB ketone values between 0.3 and 1.5 mmol/L.  Ketones can be higher if you are fasting, restricting calories, exercising or consuming more dietary fat than usual. However, blood ketones will probably decrease over time as your body adapts to a ketogenic diet, so try to resist the temptation to keep adding extra dietary fat to maintain elevated ketone levels.

Virta ketone values

The crowd-sourced data above align well with ketone data from the Virta study one-year results (Phinney et al., 2017) where they aimed to get participants with diabetes into nutritional ketosis.  

The distribution of BHB levels over the first ten weeks of the Virta trial are shown in the chart below.   While there were some higher values, many people had blood ketone values less than 0.5 mmol/L.

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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” (I.e. BHB > 0.5 mmol/L).  In spite of this, their reduction in HbA1c was substantial. Many of the people on insulin were able to reduce or eliminate their insulin requirements.  They also lost a significant amount of weight.

The chart below shows the average Virta results over the first year, with ketones rising from 0.18 mmol/L to 0.6 mmol/L initially, but then decreasing to less than 0.3 mmol/L and one year.  

The soon to be published two-year results show that blood ketone levels remained at 0.27 mmol/L after two years of a ketogenic diet.  The chart below summarises the change in ketone values over the two-year duration of the study.  

While the participants in the Virta program initially saw an increase of blood ketones just into the ‘nutritional ketosis zone’ (i.e. greater than 0.5 mmol/L) on average after ten weeks, their blood ketones settled back to just above the control group on the standard western diet.  At no time did their ketone values approach the optimal ketone zone (i.e. 1.5 mmol/L according to the commonly accepted definition of ketosis).

What ketone level should you target?

Anecdotally, it seems that people who are physically fit or metabolically healthy may have lower blood ketone levels as well as lower blood sugar levels, especially after they have been following a low-carb or ketogenic diet for a while.  

Unless you are managing a chronic condition that may benefit from high ketone levels (e.g. Alzheimer’s, Parkinson, dementia or epilepsy), you could potentially save a lot of money and angst by focusing on keeping your blood sugars closer to optimal and not worry about your blood ketone levels.

Image result for chase results not ketones

Due to their oxidative priority, the glucose in your blood needs to be burned before the fat in your diet and the fat in your body.  If your glucose stores are constantly overfull, you will be ‘stuck’ burning glucose, and you will not get to use your own body fat.

Your blood glucose provides an actionable understanding of whether your glucose fuel tank is full and if you should consume fewer carbohydrates in your diet.  

The Nutrient Optimiser

If you or a loved one require therapeutic ketosis to help with the management of a chronic condition such as Alzheimer’s, Parkinson’s or dementia the Nutrient Optimiser Smart Macros algorithm will guide you to reduce your insulin load to the point that you achieve the ketone levels necessary to alleviate our symptoms.

Image result for alzheimer's parkinson's dementia

However, if you need to control your blood sugar, the Nutrient Optimiser Smart Macros algorithm can guide you to reduce your carbohydrate intake until your blood sugars stabilise while focusing on nutritious foods and meals.

Image result for blood sugar

If you are looking to lose weight, the Nutrient Optimiser will help you focus on nutritious high satiety foods and meals that will help you control your appetite so you don’t have to fight a battle with your hunger that you will eventually lose.

We’d love you to check to get your Nutrient Optimiser Free Report now to get your initial Smart Macro targets along with nutritious foods and meals that will get you moving on your journey.  

If you’re interested in seeing what foods and meals Nutrient Optimiser would recommend for you we’d love you to check out the Nutrient Optimiser Free report.  

You can also join the Nutrient Optimiser Facebook Group to ask questions and see some amazing meals.

Registrations are now open for the Free Four Week Nutrient Density Challenge.  We’d love you to sign up and see what happens when you level up your nutrient density.


  • BHB ketone measurements can be influenced by a range of things beyond diet, including activity and metabolic health.  
  • Having high levels of energy from glucose and/or ketones in your bloodstream is problematic.   
  • People with better blood sugar control and better metabolic health tend to have lower blood glucose, lower blood ketones (BHB) and higher breath ketone levels (BrAce).  
  • Blood ketone levels for people on a low-carb or ketogenic diet with healthy blood sugar levels tend to range between 0.3 and 1.5 mmol/L.  However, blood ketones tend to decrease over time as your body adapts to burning fat.
  • Reducing your intake of processed carbohydrates will help you to avoid hyperpalatable junk food which will improve satiety and helps you to eat less and lose weight sustainably with less effort.  However, reducing your carbohydrate intake to very low levels is not necessarily better. There is nothing magical about having a particular blood ketone value, ketosis or a high fat ‘ketogenic diet’ that will cause you to lose weight more quickly.  
  • If you are looking to optimise your metabolic health, tracking your blood glucose levels can be much more useful, not to mention cost-effective.    
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