Wednesday, July 27, 2011

What You See, Part 2

Part 2 (from this article):
The study participants … were followed for 12 to 20 years. Every two years, they completed very detailed questionnaires about their eating and other habits and current weight.
In other words, this study relies on the memory of the participants over 2 year intervals.  I say we shouldn’t bet the farm on the “detailed” questionnaires.  But as expensive as it likely was to run this long term study, it was much cheaper than the intervention study, which if designed well and run for the same period of time, would have actually had the potential to show causality.
The average participant gained 3.35 pounds every four years, for a total weight gain of 16.8 pounds in 20 years.
To gain 17 pounds in 20 years, one must accumulate an excess of about 8 kcal/day.  Makes you wonder why they couldn’t just exercise a little bit more each day and therefore sustain their healthy weight, right?  That is the observation and question that has ruled the weight loss science for recent times.  It seems so simple, so common sense; why doesn’t it work?  The “experts” weigh in, the same ones that have shown such consistent support for the calorie is a calorie argument as the conventional wisdom:
“This study shows that conventional wisdom — to eat everything in moderation, eat fewer calories and avoid fatty foods — isn’t the best approach,” Dr. Dariush Mozaffarian, a cardiologist and epidemiologist at the Harvard School of Public Health and lead author of the study, said in an interview. “What you eat makes quite a difference. Just counting calories won’t matter much unless you look at the kinds of calories you’re eating.”  
“There are good foods and bad foods, and the advice should be to eat the good foods more and the bad foods less,” he said. “The notion that it’s O.K. to eat everything in moderation is just an excuse to eat whatever you want.”
I’ll be real curious to know what the good doctor classifies as “good” foods, or “bad”, and how he does so.
The study showed that physical activity had the expected benefits for weight control. Those who exercised less over the course of the study tended to gain weight, while those who increased their activity didn’t. Those with the greatest increase in physical activity gained 1.76 fewer pounds than the rest of the participants within each four-year period.
Here’s where they logic becomes treacherous.  In the “carbohydrate hypotheses” that Gary Taubes laid out in “Good Calories Bad Calories”, it became clear to me that the primary mis-perception in interpreting the first law of thermodynamics was the matter of causality.  It’s one thing to say that putting a pound of fat in a calorimeter, and measuring the change in heat in that contained system, shows that a pound of fat is equal to 3500 kilo calories of energy.  It’s another entirely to say that therefore “a calorie is a calorie” and thus we should just eat less and exercise more to control accumulation of body fat.  So – did those who exercised more reduce their rate of fat accumulation, or did those who ate fewer and/or better carbohydrates, and a higher percentage of protein and fat, exercise more?  And in any event, gaining a half pound a year is better than gaining 1 pound a year, but it’s still five pounds every ten years.  Is that really the best we can hope for?  Part 3 tomorrow. (edited for format 28 July 11)

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