the carbohydrate debate

On the low carbohydrate end of this debate you have people like Dr David Perlmutter, Nora Gedgaudas, Ron Rosedale and Dr William Davis arguing that you should restrict carbohydrate for metabolic and brain health as well as the prevention and cure of a range of diseases.

Below is one of the more confronting charts from Dr Perlmutter’s Grain Brain showing that the rate of brain shrinkage with age increases dramatically once we get an HbA1c of more than 5.2%.

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Increasing HbA1c is correlated with an increased risk of cancer, particularly once we get an HbA1c over about 6% (i.e. average blood sugar of 7.0mmol/L or 126mg/dL).

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The risk of cardiovascular disease, coronary heart disease and stroke all increase once an HbA1c greater than 5.0%, and especially over 5.4% is reached.

It is also worth noting that being on antidiabetic medication, even if it reduces your blood sugar, does not reduce your risk of heart disease.

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Perhaps keeping your blood sugar under control is the most important thing you can do to manage your health and slow the aging process, regardless of whether you have been formally diagnosed with diabetes.

If you are not getting HbA1c checked regularly you can use the average blood glucose results from your home blood sugar meter (i.e. fasting, before meals and after meals).

The conversion between HbA1c and average blood sugar are shown below.  I have also added risk level values based on the cardiovascular disease data above, and ketone values based on my data as discussed in this article.

HbA1c average blood sugar ketones
 (%)  (mmol/L)  (mg/dL)  (mmol/L)
low normal 4.1 3.9 70 2.1
optimal 4.5 4.6 83 1.3
excellent < 5.0 < 5.4 < 97 > 0.5
good < 5.4 < 6.0 < 108 < 0.3
danger > 6.5 > 7.8 > 140 < 0.3

One of the most extreme proponents of the restricted carbohydrate dietary approach is Dr Ron Rosedale who says that carbohydrates cause oxidation in the body, and that we should do everything we can to minimise oxidation by minimising carbohydrates ingested.

While the body does need glucose, it is preferable to have the body make it via gluconeogenesis (from protein) rather than directly feeding the body carbohydrates which will lead to oxidation. [3]

mainstream recommendations

On the other extreme you have dieticians recommending the USDA food pyramid telling us that we can’t survive without our healthy whole gains and that our brains run on glucose and hence we need to eat carbs or else.

The generally accepted diagnosis levels for type 2 diabetes are shown below.  Currently one in twelve adults worldwide are classified as diabetic based on this criteria.  This number is forecast to grow by more than half over the next two decades to 592 million people by 2035. [4]

  Fasting After meal
  (mg/dL) (mmol/L) (mg/dL) (mmol/L)
“normal” < 100 < 5.6 < 140 < 7.8
Pre-diabetic 100 – 126 5.6 – 7.0 140 – 200 7.8 – 11.1
Type 2 diabetic > 126 > 7.0 > 200 > 11.1

Comparing these diabetes diagnosis criteria with the optimal levels it is clear that blood glucose levels that are considered “normal” are far from optimal.  By the time you are “pre-diabetic” you are well into the danger zone!

the middle ground?

Somewhere between the dieticians and the low carb zealot you have people such as Paul Jaminet, Chris Kresser and Robb Wolf who advocate for some carbohydrates for the majority of the population.

When you listen to the argument a little closer though, it is interesting to find that even these respected health experts are all talking about a level of carbohydrates much lower than the typical western dietary intake and the typical mainstream recommendation.

Chris Kresser recommends 20 to 30% carbs for healthy people and says that a lower carb ketogenic approach will likely be beneficial for people with Alzheimer’s, dementia or neuro-degenerative disorders. [5]

Paul Jaminet’s definition of “low-carbohydrate” means eating less than the body’s glucose utilisation which forces the body to make up the deficit via gluconeogenesis. [6]  Jaminet says that the body’s preferred source of fuel is fat.  However the body typically runs on a mix of around 30% glucose for fuel (or about 600 calories per day).

Jaminet notes that if we eat more than around 30% carbohydrates the liver will end up with more glucose than it can store and we will end up with excess glucose in the blood.  The pancreas will secrete insulin to remove this excess sugar and store it as body fat.

If we eat less than 30% carbohydrates the body will convert protein to glucose through gluconeogenesis, and the risk of excess sugar in the blood is reduced.  This balance is represented graphically in the figure below.

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the big picture

When you stand back and look at the big picture, most recommendations are that that the general population should be consuming significantly less carbohydrates than are consumed in the typical western diet.

There is no perfect diet or level of carbohydrates that suits everyone.  Active people or those who are not metabolically broken will be able to tolerate more carbohydrates because they will be burning them quickly rather than storing them.

People who are sedentary or obese (i.e. 70% of the western population these days) or those with blood sugar dysregulation should opt for a carbohydrate restricted approach.

Jaminet also points out that there is an ideal range for blood sugar.  While people operating in ketosis can tolerate lower blood glucose levels while being asymptomatic, extremely low levels of blood sugar will lead to decreased health and eventually death.  That is, there is a lower limit for blood sugar, however your body will do everything it can to stop you from getting there.  So in the absence of injecting too much insulin it is probably not going to be an issue for most people.

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Similarly, at high levels of blood sugar we will get the numerous complications of high blood glucose and diabetes.  Somewhere between these two extremes is an optimal blood sugar level which Dr Richard Bernstein puts at about 83mg/dL or 4.6mmol/L. [8]

so just tell me what to do!

In view of the fact that the various health markers shown above start to go pear shaped beyond a HbA1c value of about 5.0mmol/L and then really start to fall apart above a HbA1c of 5.4mmol/L, I think it makes sense to reduce your insulin load until you get your blood sugar into the ‘good’, if not ‘excellent’ or ‘optimal’ ranges as shown in the table below.

HbA1c average blood sugar ketones
 (%)  (mmol/L)  (mg/dL)  (mmol/L)
low normal 4.1 3.9 70 2.1
optimal 4.5 4.6 83 1.3
excellent < 5.0 < 5.4 < 97 > 0.5
good < 5.4 < 6.0 < 108 < 0.3
danger > 6.5 7.8 > 140 < 0.3

If you’re a Kitavin eating fruit in the jungles of Papua New Guinea or Rich Froning living off peanut butter and sweet potato, that might mean you should keep on doing what you’re doing.

If you look in the mirror and see a bit more body fat than you’d like, it probably means you might benefit from actively managing the glucose levels and insulin load of your diet.

Once you get them into the excellent range you will automatically tap into ketosis which will mean that you will be burning fat for fuel and losing weight without feeling like you are starving yourself!

If you are looking for more inspiration on what to do at this point check out the list of optimal foods here and optimal meals here.

Learn more about how to bring your blood sugars in line here, how to lose weight here, and what to eat if you’re lucky enough to be a metabolically healthy and fit athlete here.

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[1] http://www.drperlmutter.com/important-blood-test/

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

[3] https://vimeo.com/52872503

[4] http://www.dailymail.co.uk/health/article-2997882/Diabetes-epidemic-400-million-sufferers-worldwide-Number-condition-set-soar-55-20-years-unless-humans-change-way-eat-exercise.html

[5] http://chriskresser.com/how-to-feed-your-brain from 9:25

[6] http://perfecthealthdiet.com/2011/10/jimmy-moore%E2%80%99s-seminar-on-%E2%80%9Csafe-starches%E2%80%9D-my-reply/

[7] http://perfecthealthdiet.com/2011/11/safe-starches-symposium-dr-ron-rosedale

[8] https://www.youtube.com/watch?v=zJGAbZIvRh8

[9] http://www.dietdoctor.com/lose-weight-by-achieving-optimal-ketosis

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