As you know, I tend to be a lumper rather than a splitter. I look for common themes rather than unique storylines. Along those lines, I view low carb & low
glycemic index diets as variations on a theme: less than typical carbohydrate consumption. But a
study published yesterday in JAMA suggests that
low carb diet results in less reduction in resting energy expenditure (REE) & total energy expenditure (TEE) compared to low glycemic diet which in turn has less reduction in REE & TEE compared to low fat diet.
The authors arrived at their conclusion via a very clever crossover study in which each of 21 overweight or obese adult avg 30yo avg body mass index 34.4kg/m2 served as his/her own control. In other words, over the course of 12 weeks, the subjects consumed an isocaloric diet of various composition for 4 weeks in a randomized fashion. The typical high glycemic load, low fat diet gathered 60% of its energy from carbohydrates w/20% from fat & protein each. The low glycemic index, moderate glycemic load diet obtained 40% of its energy from carbohydrates & fat each w/20% from protein whereas the low carb, low glycemic load diet obtained 10% of its energy from carbohydrates, 60% from fat & 30% from protein.
My first reaction is that it's a
sad commentary on our times when a 12 week study of 21 subjects garners national headlines. But on further introspection, I find myself wondering if I'm ready to make recommendations to a large proportion of the population based upon such a small, short study. Let's just say that this study makes for excellent hypothesis development.
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