Phinney and Volek since 2011 say: “Above 1 mmol/L (of blood ketones), more than half of the brain’s fuel comes from ketones.” A Test: is this true?

Last review and update: October 26, 2020.

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A Test of Physiological Literacy.

In their 2011 book (1), Phinney and Volek stated:

“Above 1 mmol/L (of blood ketones), more than half of the brain’s fuel comes from ketones.”

1. Is the statement above correct?

2. What percentage of brain energy do ketones provide at ketone blood levels of a) 0.5mmol/L, b) 1.5 mmol/L, c) 3 mmol/L?

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An extended citation form the 2011 book by Phinney and Volek.

Volek, J., Phinney, S. D., Kossoff, E., Eberstein, J. A., & Moore, J., 2011 (1):

What is remarkable to those of us with expertise in human metabolism is the the US Dietary Guidelines Advisory Committee’s (DGAC) statement that the human brain is carbohydrate dependent, thereby mandating a high intake of dietary carbohydrate. Interestingly, this was written not by lawyers and journalists like the original McGovern Committee report, but by a committee of physicians and PhD scientists. They should know better. In fact, the human brain is a carbohydrate-dependent organ ONLY if one routinely eats a lot of anti-ketogenic nutrients such as sugars and concentrated carbohydrates. When dietary carbohydrates are held to 50 grams or less per day, humans undergo a process called keto-adapation, causing the liver to make and release ketones into the bloodstream. After a few weeks of the keto-adaptation process, serum ketones increase severalfold, reaching 1-3 millimolar (mM).

Above 1 mM ketones, more than half of the brain’s fuel comes from ketones. The rest of the brain’s fuel must indeed come from glucose, but this amount (usually less than 50 grams per day) is easily produced endogenously by the liver from ‘metabolic left-overs’ via a process called gluconeogenesis. Thus, the brain uses glucose in varying amounts depending upon the availability of ketones. The manifest ability of the body to supply the brain with fuel independent of dietary carbohydrate intake clearly contradicts this committee’s assertion that the brain is a carbohydrate-dependent organ. Simply put, this is a classic case of a false premise leading to a false conclusion.

Related:

A serious error in the way Volek et al. designed their 2016 FASTER study.

Deconstructing Stephen Phinney’s early studies.

Debunking Nina Teicholz: The dietary guidelines tell us to eat low carb (100g/d of carbs). Nina has not read them.

Selected references:

1. Volek, J., Phinney, S. D., Kossoff, E., Eberstein, J. A., & Moore, J. (2011). The art and science of low carbohydrate living: An expert guide to making the life-saving benefits of carbohydrate restriction sustainable and enjoyable. Lexington, Ky: Beyond Obesity.