the Goldilocks glucose zone
- The body requires somewhere between 160 and 600 calories per day from glucose.
- This glucose can be sourced both from ingested carbohydrates as well as the glucogenic portion of protein not used for growth and repair.
- Rather than raising blood glucose immediately, amino acids from protein circulate in the blood until they are required.
- Excessive glucose from either carbs or protein will lead to increased insulin requirement, insulin resistance, diabetes, obesity and a range of other issues associated with hyperinsulinemia and metabolic syndrome.
- Someone who is insulin resistant and/or has diminished pancreatic function does not produce adequate insulin to maintain normal blood glucose. Rather than using diabetes medications or exogenous insulin, the alternative option is to decrease one’s dietary insulin load to a point that the body’s natural insulin production can keep up.
- We can manage our dietary glucose to achieve normal blood sugars by considering the total insulin load from carbohydrate plus the glucogenic portion of protein.
Rather than simply focusing on the ideal macronutrient split, this article endeavours to take the discussion one step further to look at how we can optimise the split between dietary glucose and fat given that glucose can be obtained from both carbohydrates, and the glucogenic portion of protein in excess of the body’s requirement for growth and maintenance.
the Goldilocks glucose zone
This article outlines a basis upon which to determine the optimum balance between what are often polar extremes.
On the high glucose end of the argument we are faced with the following issues:
- high insulin levels,
- obesity and excess fat accumulation,
- high blood glucose levels,
- heart diseases risk, and
- the plethora of issues that accompany metabolic syndrome and hyperinsulinemia.
At the ketogenic extreme, we have concerns about a range of issues including:
- inadequate fuel for the brain,
- limited food options,
- a lack of vitamins and minerals,
- low fibre,
- stunted growth,
- impaired athletic performance, and
- high cholesterol levels.
Somewhere in the middle, there must be an optimal balance of fuel for each individual, a balance between the extremes.
But how do we find this balance point? Then what do we monitor to ensure we stay there?
Not too hot. Not too cold.
Not too hard. Not too soft.
What we are searching for is the “Goldilocks glucose zone”.
the safe starches debate
The ‘safe starches debate’ has been intriguing and has informed my thinking on this controversial issue.
The discussion started at the 2012 Ancestral Health Symposium with a panel hosted by Jimmy Moore.  It continued on the blogs of the two lead representatives of each side of the argument, Paul Jaminet  and Ron Rosedale .
the case for limiting carbohydrates
On the low carb end of the debate, we have Ron Rosedale who argues that:
1. Non-fibre carbohydrates are:
- detrimental as they lead to increased insulin levels, oxidation and accelerated ageing, and
- unnecessary as we can obtain our glucose needs via gluconeogenesis from protein.
2. Glucose can be manufactured from glycerol or from lactate and pyruvate recycling. In some respects, this is even better than making glucose from protein. 
natural glucose utilisation level
On the not so low carb end of the argument, Paul Jaminet argues that the human body runs on a fuel mix of about 30 to 35% of calories from carbohydrates (say 600 calories per day). The remaining 70% or so of our fuel comes from fat.
Jaminet recommends that people follow a ‘low carb’ diet, however, Jaminet’s version of low carb is a carbohydrate intake somewhere less than the body’s 30% requirement for glucose. This forces some proportion of the glucose needs to come from gluconeogenesis.
When you look at this in the context of the fact that the typical western diet has 40 to 50% of calories coming from carbohydrates, we are really arguing over whether a low carb diet or a very low carb diet is best for our metabolic health.
Jaminet’s glucose flux has a lot of similarities with Mark Sisson’s Primal Blueprint Carbohydrate Curve.  Jaminet’s 600 calories equates to 150g of carbohydrates which aligns with the top end of Sisson’s ‘effortless weight maintenance zone’.
But what if limiting carbohydrates to less than 150g per day is not working for you (e.g. your blood sugars are not in normal range or you are not achieving weight loss)?
What can we learn from the food insulin index data to help us build on standard carbohydrate counting?
How can we determine the optimum fuel mix for our individual situation, body and goals?
minimum carbohydrate requirement
One of the concerns about a low carbohydrate diet centres on the understanding that the brain needs carbohydrates.
This seems to stem from Institute of Medicine’s advice that the brain needs about 400 calories per day from glucose. This equates to 100g of carbs which most people wind up to 130g to provide a safety factor.
The IOM, however, notes that a person who is fat adapted can run on lower amounts of carbohydrates as their brain is fuelled by ketones and there is no minimum requirement for carbohydrates, only glucose which can also be obtained from gluconeogenesis.   In spite of this, nutritionists still recommend a minimum carbohydrate intake.
Jaminet makes a similar differentiation that a typical sedentary person requires about 600 calories for glucose per day, however, this may decrease to 300 calories per day for someone on a ketogenic diet.
The understanding of the absolute minimum glucose requirement comes from research by George Cahill who undertook extreme starvation experiments and found that people could survive on as little as 40g of glucose per day (i.e. 160 calories). 
In the fed state the body will rely on glucose from ingested carbohydrates. After a period of fasting, it transitions to using glucose from the glycogen stores in the liver and muscles. Once the glycogen stores are exhausted the body will obtain glucose via gluconeogenesis from cannibalising muscle.
At this point however the brain and the rest of the body have largely transitioned to being fuelled by fat so it only needs to obtain 40g of glucose per day from protein via gluconeogenesis. This would equate to around 5% of calories from glucose (not necessarily from carbohydrates).
I am not suggesting that starvation ketosis is optimal for most people. The point is that the body can survive on very little glucose if it needs to for quite a long time.
The longevity crowd will tell you that this is an evolutionary advantage so you can prolong life until a time when there is enough nutrition to reproduce and thrive. People who could use their fat and muscle for fuel survived to be your ancestors, and those that couldn’t didn’t.
what is the minimum protein requirement?
According to Nuttall and Gannon  the body requires between 32 and 46g of high-quality dietary protein to maintain protein balance.
This equates to around 6 to 7% of calories in a 2000 to 2500 calorie diet being taken “off the top” for growth and maintenance, with everything else potentially available as excess.
The same paper notes that the American diet typically consists of between 65 and 100g of protein per day (i.e. 13 to 16% of calories).
three macros or two fuel sources?
Something that has been very interesting to me that I had not understood until recently was that protein is made up of glucogenic and ketogenic amino acids. Some amino acids can turn into either glucose or fat.  
The table below shows the differentiation of amino acids into different categories.
I will be discussing this concept in more detail in a separate article (The Insulin Index v2), however in essence, what this means is that there are really only two fuel sources for the body, glucose and fat, with “excess” protein being turned into one or the other.
well formulated ketogenic diet
Steve Phinney is probably the most well respected authority on the ketogenic diet. This figure shows a comparison of what Phinney calls the “well formulated ketogenic diet” (WFKD) as a triangle with a number of possible dietary approaches shown for comparison. 
A WKFD can contain 30% protein and 5% carbs or 20% carbs and 10% protein. A WKFD, however, cannot, however, contain 30% protein and 20% carbs because we would get too much glucose which would increase insulin and suppress ketosis.
As shown in the WFKD figure above the protein content of a ketogenic diet can range between 0.8 and 2.4g/kg lean body mass. However, if we are running higher levels of protein we will only achieve ketosis if we also limit carbohydrates.
Listen to Steve Phinney discuss this concept from 2:51 in this video.
Interestingly, the slope of the line along the face of the WKFD triangle corresponds with the assumption that 7% of protein goes off to muscle growth and repair with 75% of the remaining ‘excess’ protein being glucogenic. This also aligns nicely with the observation from the food insulin index data and the theoretical proportion of glucogenic amino acids in protein.
the Goldilocks glucose zone
Listed below are the various levels of glucose requirement in terms of calories discussed above along with the equivalent carbohydrates and the percent of glucogenic calories in a 2250 calorie diet.
|approach||glucogenic calories||insulin load (g)||glucogenic (%)|
|glucose utilisation (Jaminet)||600||150||26.7%|
|ketogenic threshold (Phinney)||500||125||22.2%|
|ketogenic maintenance (Jaminet)||300||75||13.3%|
- The glucose utilisation is Jaminet’s approximation of the glucose calories used by a non-ketogenic person each day. If we run above this level our glycogen stores will become overfull, with excess glucose spilling into the blood, requiring insulin and being stored as fat. Below this level, we need to obtain some of our glucose from protein via gluconeogenesis.
- The ketogenic threshold represents the theoretical boundary between the WFKD and the rest of the world according to Phinney’s protein vs carbohydrates plot. Below this point, our glycogen stores will become depleted to a point that we be forced to rely on our protein and fat stores for energy rather than carbohydrate. After a period of consuming fewer carbs than required to keep our glycogen stores topped off, we will start to show ketones in our blood and rely on ketones and fat more than glucose. This level is about 500 calories per day which is about 22% of a 2250 calorie per day diet.
- The ketogenic maintenance level is based on the 300 calories per day that Jaminet says we need from glucose if we are fat adapted. With a greater proportion of energy coming from fat in the form of ketones we require less glucose for brain function.
- The starvation level represents what people can survive on as an absolute minimum. In this extreme starvation state, the body is cannibalising muscle via gluconeogenesis to convert to glucose to survive. This is not something I recommend you try at home. However, it is useful to know that the body can survive (but not necessarily thrive) at very low levels of glucose for a significant period of time.
The chart below shows these glucose levels superimposed on a plot of protein versus carbohydrate. The points on the left-hand side of the chart labelled with calorie values represent the point at which all glucogenic calories come from carbohydrates with only the minimum 7% protein for maintenance ingested (i.e. no “excess” protein).
As we move to the right we have increasing levels of protein and decreasing levels of carbohydrates to maintain the same total number of glucogenic calories (assuming that 75% of “excess” protein converts to glucose).
The only thing we can be certain of here is that the concepts shown graphically in this figure will not be accurate due to the fact that it is built on a number of layers of theory. And everyone’s body is different. However, this chart gives us a conceptual framework with which to manipulate our diet to achieve our goals.
The take home message is that, if we are trying to reduce the glucose load of our diet to the point at which our own pancreas can keep up, we need to think, not just in terms of carbohydrates, but in terms of total glucose (or insulin load) from carbohydrates plus excess protein.
I don’t think the body minds that much whether it gets glucose from carbohydrates or protein.  My view is that it is better to maximise vitamins (generally from carbohydrate containing foods) and amino acids (from protein containing foods) as far as possible while at the same time keeping our glucose load within our own pancreas’ ability to keep our blood sugars at normal levels. What this means is that some people may need to restrict their carbohydrates and their protein more than others to achieve normal blood sugars.
what about the Kitavans?
When faced with the hormonal theory of obesity many people are quick to point to hunter gatherer populations such as the Kitavans that do quite well on high levels of carbohydrates.
Some people seem to tolerate high levels of carbohydrate from whole food sources. Perhaps they are metabolically flexible such that they can store carbohydrates as fat and quickly use them again, or they are very active and hence using up their glycogen stores regularly, and are very insulin sensitive and adapted to handle significantly more than 600 carbohydrate calories per day from whole food sources.
It may also be that people eating predominantly unprocessed high fibre foods are less likely to be in a caloric excess meaning that they do not have a lot of left over calories to store as fat or to require excess insulin.
Dr Jason Fung points out in this video that in spite of a higher glucose load the Kitavans managed to keep low insulin levels, which seems to be the critical factor.
If you are highly active with great insulin sensitivity and you can consume high levels of carbohydrates while maintaining normal blood glucose and staying lean then good luck to you. I’m jealous. Enjoy, at least while it lasts!
It is worth noting that a number of the champions of the low carbohydrate movement such as Tim Noakes,  Ben Greenfield  and Sami Inkenen  found that they had or were becoming diabetic after decades of extreme exercise on a high carbohydrate diet, hence transitioned to a low carbohydrate approach to manage their blood sugars.
comparison of dietary approaches
To help make more sense of this concept I have shown a number of dietary approaches from the article Diet Wars… Which One is Optimal? on the protein vs carbohydrate chart below.
- Bernstein’s approach is designed to be high protein, low carb, to provide diabetics with their glucose needs from protein which releases glucose more slowly than carbohydrate.
- This version of the Atkins diet is unlikely to be ketogenic due to the high levels of protein. Reducing carbohydrates and/or protein is likely to be necessary to achieve ketosis, and possibly the weight loss that is typically the aim of the Atkins diet.
- The Zone and Mediterranean diets, though generally thought to be moderate carbohydrate dietary approaches, are still well above Jaminet’s glucose utilisation threshold.
- Terry Whals’ Paleo Plus approach achieves a good balance between maximising nutrition through the use of high fibre vegetables and MCT oil without excess protein.
- The 80% fat diet approach is below the ketogenic maintenance level of 300 glucogenic calories per day but still above starvation ketosis. Personally, I think it would be hard for most people to get optimal levels of vitamins, minerals, fibre and possibly protein at these levels without supplementation or focussing on nutrient dense organ meats. However it may be desirable for someone using ketosis therapeutically for something like cancer or epilepsy.
The typical western diet contains between 40 to 50% carbohydrates, 35 to 40% fat and 15 to 20% protein.  The figure below shows that between 1970 and 2000 carbohydrate intake increased from around 42% to around 49% for men while protein intake has largely stayed constant. During this period obesity increased from 14.5% to 30.9%. 
It’s fair to say that macronutrient composition is only part of the story, but perhaps if we moved the carbohydrate intake back towards the ketogenic corner (along with a shift to more whole unprocessed foods) this trend would turn around again?
what is our light on the horizon?
So how do you decide what dietary approach is optimal for each individual? What is right for you? What is the lighthouse on the horizon that you can guide your boat of metabolic health towards?
Building on this I developed this table showing the relationship between HbA1c, average blood sugar and ketone values for different heart disease risk categories.
|HbA1c||average blood sugar||ketones|
|excellent||< 5.0||< 5.4||< 97||> 0.3|
|good||< 5.4||< 6||< 108||< 0.3|
|danger||> 6.5||7.8||> 140||< 0.3|
Everyone should be striving for optimal blood sugar control in order to manage their overall health and reduce a plethora of risks.
The point where you achieve excellent blood sugar control (i.e. average blood glucose less than 5.4mmol/L) is about where most people will start to show low levels of ketones in their blood. This is likely to be somewhere around Phinney’s ketogenic threshold (orange line in the protein / carb plot).
People with more severe issues such as extreme insulin resistance, epilepsy, morbid obesity or cancer may choose to push deeper into ketosis beyond the point of simply achieving normal blood sugars and normal HbA1c. This may require more discipline, intentional supplementation and limitation of food selection than most people are willing to invest.
what gauges do we use to steer the boat?
The most successful diets are the ones that people can stick to.
To this end I have developed a list of optimal foods that prioritises low insulin load, high fibre, nutrient dense foods based on your personal goals (e.g. weight loss, blood sugar control, nutritional ketosis, athletic performance or therapeutic ketosis). I have also developed this database of optimal meals that will enable you to easily choose simple everyday meals that will provide high levels of nutrition while achieving a low insulin load.
If you have diabetes or insulin resistance then I recommend that you track your blood sugars and ‘eat to your meter’. You will quickly learn what meals raise your blood sugars and hence what to avoid.
With the understanding that non-fibre carbohydrates plus excess protein raise blood sugar and require insulin you can work to manage your diet until you achieve the excellent blood sugar levels with a reduced or ideally eliminated reliance on medications.
Many people benefit from journaling or tracking food intake on an app such as MyFitnessPal or Cronometre. Rather than looking at calories or carbohydrates I encourage you to consider insulin load which can be calculated using this formula.
As shown in the table above, you will likely need to get below an insulin load of 150g per day to be under the blue line and under 125g per day to be ketogenic.
While I don’t think it is healthy, natural or normal to consciously monitor everything you eat for extended periods, many people find it useful for a period of time to retrain their habits or to help guide them toward a short term goal.
As a worked example I have calculated the insulin load, % insulinogenic calories as well as the % carbs and % protein for Deshanta from the Optimising Nutrition Facebook group who provided her MyFitnessPal food diary which is summarised in the table below.
|carb (g)||fat (g)||protein (g)||fibre (g)||insulin load (g)||% insulinogenic||% carb||% pro|
I’ve also plotted this on the chart below indicating that her diet puts her just outside the realm of a ‘well formulated ketogenic diet’. If she wanted to improve her blood glucose control further she could consider moving back towards the more ketogenic bottom left of the chart by reducing carbohydrates and / or protein.
If you’re interested in seeing how you can refine your diet to balance your blood sugars with consideration of your blood sugars and glucose load as well as your vitamins and amino acid you could join this closed Facebook group.
what are the levers we can use to steer the boat?
In order to reduce the insulin load of our diet we should do the following:
- Increase fibre from non-starchy vegetables (e.g. spinach, mushrooms, peppers, broccoli etc). These will provide vitamins and minerals as well as indigestible fibre that will feed the gut which will also improve insulin resistance.  Increasing fibre in our diet will increase the bulk and the weight of our food without increasing calories or insulin and will tend to decrease our cravings for processed carbohydrates.
- Reduce carbohydrates, particularly ones that come in packages with a bar code. Enough said.
- If you are not getting the desired results, look to reduce your protein intake until you are achieving excellent blood sugar control and/or your target HbA1c.
- If you are still not getting the results you want then look at some form of intermittent fasting to improve your insulin sensitivity and to kick-start ketosis. 
Once you are achieving normal blood sugars you may want to occasionally test your blood ketones to confirm you have achieved nutritional ketosis; however tracking your blood sugars will be adequate for most people.
Once you have achieved your desired level of blood sugars, weight and metabolic health you can drop back to monitoring less frequently, just to make sure you are not regressing and then ramp up the efforts again if required.
Then, go outside. Move. Have fun. Find a hobby. Enjoy life! And stop thinking so much about food!
 See also discussion in Chapter 7 of Richard Feinman’s “The World Turned Upside Down: The Second Low-Carbohydrate Revolution”.
 Though it does take more energy to convert protein to glucose, hence a calorie is not a calories when it comes to protein being converted to glucose via gluconeogenesis.
post updated July 2017