Posted by: Lowell | May 23, 2009

Links: Article in Nature and Review of Taubes

Two quick links I want to share.  The first is an article in the journal Nature:

And the second is a great review of Good Calories, Bad Calories by Gary Taubes, on of my favorite books and best sources of information, written by Robert McLeod, a grad student up in Edmonton—whose primary interests are energy and physics, not medicine and biochemistry:

 

The Nature article does a good job of pointing out that obesity is not a disease of lifestyle, and that “evidence suggests that the balance between energy intake and output is largely controlled by a powerful, unconscious biological system”.  Well put, Nature, well put.  Free access to calories is a permissive factor in obesity, but not causative.  It doesn’t quite make it all the way to the real causes and any real solutions, and ends up suggesting the same old tired advice, but before it loses its way the article does a great job of explaining why and how the human body self regulates weight, how powerful that system is, and why calories-in/calories-out is not a reasonable or effective approach to weight loss.

The GCBC review is a ton of fun—not only does it do a great job summarizing many of the points of the book in Cliff’s Notes form, but the author, being primary an energy/physics guy, really digs into the energy equation at the basis of all modern obesity thinking, namely that the change in energy or mass in a person is equal to energy in minus energy out.  Taubes (and many others) point out that this is true, but that everyone misses the key point that energy in and out are dependent variables with tons of interrelationships, and you can’t just modify one or both and expect the relationship to stay the same.  Eating 500 fewer calories a day should result in 1 pound of weight loss every week forever, but of course it only works for a very short time… they body self regulates and the dependent variables balance out again.

Anyhow, way down in the review Robert gets to what he suggests an equation for the bare starting point for energy balance in a human would be, since the normal thermodynanic equation is vastly insufficient for the task.  He comes up with:

Human Energy EquationWow.  Wonder what happens if you only modify only two of those variables (calories consumed and calories burned via exercise)?  Pretty much nothing in the medium or long term, the feedback loops and dependencies balance back out quickly.

Both links are pretty good; check ‘em out.

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