Review of a Critique of GCBC, Carbohydrate Hypothesis, Part 1

I found a critique by a fellow that takes issue with Gary Taubes and his ‘carbohydrate hypothesis’ (CH).  Taubes’ summation of the CH is presented in his book Good Calories, Bad Calories (GCBC).  I’ve read that book about four times because I want to understand it – and I think it is that important.  This author, (http://www.thebsdetective.com/2009/10/bullshitter-of-day-oct-7th-gary-taubes.html), Mr. BS, sees it differently.  I’ll use several posts to review Mr. BS’s critique.

Taubes’ hypotheses from GCBC are here: http://fireofthegodsfitness.blogspot.com/2010/03/tubs-of-taubes.html

Gary Taubes does not claim authorship of the CH, because as he reports in his book the CH was the conventional wisdom for the better part of the last 150 years.  The idea that eating fat makes one fat is a relatively new idea – a low fat, high carbohydrate diet is a fad diet. 

Mr. BS lists as his credentials a master’s degree in nutrition, and he points out in a “confident” style he’s been published in ‘prestigious’ professional journals.  There’s an implied arrogance in the very title of his post – who’s he to award “bullshitter of the day” status to others?  He also utilizes some language that strikes me as fairly pretentious, such as: “Taubes is a journalist (not a scientist).”  Why does he think this is a significant distinction?  Another choice quote: “I am going to approach the carbohydrate hypothesis as a true scientist should approach it.”  This implies he knows true science, whereas Gary Taubes does not.  One can only get away with this sort of pompous attitude if they are very, very good at what they do.

To be forthright about my bias, I see Gary Taubes as a noteworthy scientist (not to be confused with an in the lab researcher), and I believe his impact on health and nutrition will be historic and positive.  Credentials rarely impress me.  What most impresses me is clear thought, intellectual integrity and a well presented case.  What follows is an effort to use Mr. BS’s criticism to highlight some of the more useful insights one can gain from GCBC.

For the purpose of this series of posts, the definition of healthy carbohydrate intake is “less than 100g/day of non-starchy vegetables.”  “Excess carbohydrate intake” will be the term used to describe a an intake of carbohydrate that would increase blood glucose levels to a dangerous level unless controlled by insulin secretion.  Practically, what that means is eating too much grain, potatoes, corn, rice, sugar (or one of the other plant foods high in glycemic load) or processed foods which are typically loaded with both sugar and fat.

Mr. BS starts by illustrating, at best, an imprecise understanding of the CH.  The essential part of Taubes’ message in GCBC relates to causality and the impact of causality in understanding the energy balance equation and applying it to human metabolism.  His primary point on this topic is that while the energy balance equation is not the least bit in question (it is after all the First Law of Thermodynamics), the application of this law to human obesity is not particularly useful because it does not give any insight into causality. Or, as a physicist puts it:

“Applying the 1st Law to living organisms is Proof by Tautology. Yes, 1 + 1 = 2, but this tells us absolutely nothing about the underlying mechanics. The 1st Law does not (I repeat N-O-T) tell us whether you store excess energy in the form of fat, or bleed it off into the atmosphere by dilating blood vessels next to the skin, sweating, etc. To do so would require an accounting of entropy.”

(http://entropyproduction.blogspot.com/2009/02/all-medical-science-is-wrong-within-95.html - this post is worth reading in its entirety):

Mr. BS states: “Taubes blames carbohydrate, not increased food intake, for the epidemic of obesity in this country.”  More accurately stated, Taubes believes:

6. Consuming excess calories does not cause us to grow fatter, any more than it causes a child to grow taller. Expending more energy than we consume does not lead to long-term weight loss; it leads to hunger.

7. Fattening and obesity are caused by an imbalance- a disequilibrium – in the hormonal regulation of adipose tissue and fat metabolism. Fat synthesis and storage exceed the mobilization of fat from the adipose tissue and its subsequent oxidation. We become leaner when the hormonal regulation of the fat tissue reverses this balance.

In GCBC Taubes points out that using government stats for estimates, it appears that carbohydrate consumption has increased since the 1970s, while fat consumption has been stable.  But the CH does not require that we know that there is or is not increased energy consumption in our fattening population.  The important issue is causality.  The consumption of excess carbohydrate causes storage of energy as adipose tissue, and/or a reduction of expenditure of energy by the body.  How?  I’ll explain further, as we work through Mr. BS’s critique tomorrow.