Today a new article by Gary Taubes was published in the British Medical Journal. It’s entitled, “The science of obesity: what do we really know about what makes us fat?“, and it’s a good one.
Those of us who have read Why We Get Fat or Good Calories, Bad Calories will find much that is familiar here, but I appreciate Taubes’ frequent reminder that our notions of the drivers of obesity may be tragically flawed.
the energy balance notion has an obvious flaw: it is tautological. If we get fatter (more massive), we have to take in more calories than we expend—that’s what the laws of thermodynamics dictate—and so we must be overeating during this fattening process. But this tells us nothing about cause. Here’s the circular logic:
Why do we get fat? Because we overeat.
How do we know we’re overeating? Because we’re getting fatter.
And why are we getting fatter? Because we’re overeating.
And so it goes, round and round.
“The statement that primary increase of appetite may be a cause of obesity does not lead us very far,” wrote the Northwestern University School of Medicine endocrinologist Hugo Rony in 1940 in Obesity and Leanness, “unless it is supplemented with some information concerning the origin of the primarily increased appetite. What is wrong with the mechanism that normally adjusts appetite to caloric output? What part of this mechanism is primarily disturbed?” Any regulatory defect that drove people to gain weight, Rony noted, would induce them to take in more calories than they expend. “Positive caloric balance would be, then, a result rather than a cause of the condition.”
Having introduced the familiar tautology behind many explanations of obesity, Taubes returns to familiar territory by examining the history of competing theories of obesity, ending in the current epoch with a castigation of the observational studies that overstep their bounds by assuming correlation equals causation.
The problems with observational studies are manyfold, and no doubt are familiar to many in the community. Taubes doesn’t stop there though. He continues with a look at the sad state of experimental trials and the need for better research and science. Finally, he concludes:
Finally, if the best we’ve done so far isn’t good enough—if uncontrolled experiments and observational studies are unreliable, which should be undeniable—then we have to find the willingness and the resources to do better. With the burden of obesity now estimated at greater than $150bn (£100bn; €118bn) a year in the US alone, virtually any amount of money spent on getting nutrition research right can be defended on the basis that the long term savings to the healthcare system and to the health of individuals will offset the costs of the research by orders of magnitude.
And it’s true. And this speaks directly to PaleofastUK’s concerns from yesterday. We can’t accept shoddy science and subpar research, regardless of where it’s performed. We can’t go into this attempting to prove what we already believe is true. Let the science guide the way, and take us where it may.
- The science of obesity: what do we really know about what makes us fat?, Gary Taubes. British Medical Journal 2013; 346 doi: http://dx.doi.org/10.1136/bmj.f1050 (Published 16 April 2013)
- Why We Get Fat, Gary Taubes
- Good Calories, Bad Calories, Gary Taubes