Sunday, 13 February 2011

High protein brain food with a side order of offal

I have been reading 'Why We Get Fat' by Gary Taubes.  I like the way this author writes and came away with a positive feeling about the book.  He delivers his message in three servings - first he debunks the so-called 'calories in/calories out' model of popular and official lore.  The author lays out a decent set of easily understandable counter-examples to the generally held belief that we embody a linear relationship between how much we eat and how much we weigh.  Things are not that simple, he correctly tells us.  Next, he gives us the highlight of the book - a decent primer on lipid metabolism and particularly how it interacts with our dietary habits.  His descriptions of what could have been utterly dull descriptions of metabolic pathways are impeccably clear and certainly convincing with respect to the insidious role of insulin in the fattening of the modern world.  His final chapters deal with some dietary advice, which to all intents and purposes, corresponds to the Atkins diet.

He fails to give us a feel for just how difficult it is to stay on the Atkins diet for most people.  This contrasts with his criticism of many other kinds of diet and current established dietary advice, which clearly highlights the difficulty people really find in following dietary and exercise advice.  It has left me pondering over the fact that people generally struggle to manage their diets, regardless of who's story you believe.

Taubes also doesn't address the downside risks of Atkins as rigorously as he does rival diets (ones based on less firm scientific foundations).  I think the book would have been better without part 3, though to be fair he doesn't overdo the dietary advice.  The science of lipid metabolism does indeed lend support to recent low carbohydrate dietary regimes but cannot make those prescriptions any more palatable.  

Extraordinary as it sounds, the main message - that our current high levels of carbohydrate consumption, rather than greed and sloth exclusively, are causing us to get fatter - is one whose consequences, if true, would be so far-reaching vis-a-vis our eating habits as to be out of reach.  Also, I wonder if we all really did fall quite so completely for the straw man 'calories in/calories out' story of the 60s and 70s that he caricatures in his book, especially when we consider how our culture has spent the last 80 years or so developing seemingly endless dietary permutations.  Perhaps somewhere deep in our own guts we knew there were fattening foods and non-fattening foods?  Indeed, chapter 16 is meant to be a historical digression showing how we have known about the fattening properties of carbohydrate foods for a couple of hundred years.  Is it really likely that culturally we abandoned all of this as soon as 1960s nutritionists told us to?  How obedient we all must seem to be to Taubes when it comes to official advice on diet.  That sounds quite implausible to me.  I would have liked to hear a more sociological history of how this interesting moment of counter-culture, where independence and freedom from stale convention began to take root in the Western public's consciousness happened also to be the moment where we all decided to abandon the folk knowledge we shared about fattening foods in favour of advice to control and restrict our diet.  Perhaps the religions tradition of saintly starvation played a role?

At several points in the book he comes close to implicitly agreeing with the calories in /calories out formulation and surely he has overdone his criticism of the benefits we might achieve by taking our noses out of the trough and doing some hard work.

One last criticism, there's a really quite ludicrous chapter - "The significance of twenty calories a day" - in which he presents for serious consideration an argument against calories in/out as follows.  To go from a lithe teenager to an obese 50-something, you'd need, on average, to consume an extra (i.e. paltry) 20 calories per day, and our bodies are just not designed to control our calorific balance to such a fine degree.  This Science journalist has clearly forgotten the difference between mean and variance.

My money's on a multi-modal explanation of why we're now facing a growing problem of obesity but having read this book, it is now clearer to me just how central a role metabolic pathways play.  You should read his book if you currently don't believe metabolic processes play a significant role in the overall story of the rise of obesity in the late 20th century, but don't expect metabolic processes to be the only major causal factor.