From The Urbach Letter – November 2003

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OK, So I Was Wrong... (Maybe)
At least according to Penelope Greene. Who is Penelope Greene? She's a researcher at the Harvard School of Public Health and just she presented a paper at the American Association for the Study of Obesity. Her research indicates that all calories are not created equal. Contrary to the law of thermodynamics I cited in this column last August in a piece titled The Math of Fat, Greene's study found that people on low-carb/high-fat diets can actually eat more than those on standard (high-carb/low-fat) diets – and still lose weight. I can hear Robert Atkins laughing at me from the grave...

During the 12-week study, two controlled groups of subjects ate less food than they usually do. However, some of the Atkins-type dieters ate an extra 300 calories a day more than the low-fat folks – but lost even more weight. Going by strict thermodynamics, the latter group would have been about seven pounds heavier. 300x7x12 = 25,200 extra calories. 3,500 calories extra = one pound of fat, so 25,200/3,500 = 7.2 pounds. But that didn't happen.

Twenty-one overweight volunteers were randomly assigned to either low-fat or low-carb diets. The women ate 1,500 calories a day and the men 1,800. A third group was also low-carb but got an extra 300 calories a day (for either gender). Nonetheless, everybody lost weight. On average, the lower-calorie, low-carb people took off 23 pounds, while those eating the same amount of calories in the form of more carbs and less fat only lost 17 pounds during the 12 weeks. Interestingly, the volunteers who ate the extra 300 calories a day still lost an average of 20 pounds.

Hey, I'm more than willing to revise my opinion. While I'd like to see a bigger study done before changing my eating habits, this one was reportedly well controlled (the volunteers were supplied with all food eaten during the study and were closely monitored). Scientists are still scratching their heads.. It's not often one of the fundamental laws of nature is proved false. While I'm open-minded about Atkins-type diets – I've always maintained they're a good way to lose weight quickly, but are not a lifestyle diet, due to disease risk from the high-fat animal products typically consumed – there *has* to be more to this story...