Are all calories the same?

I've been skeptical about the claimed metabolic advantage of low-carb diets. It sounds almost too good to be true, like magic: somehow, dieters on a low-carb diet lose more weight when on a low-carb diet compared to other types of diets (with identical caloric intake).

I've been looking for science-based evidence of the advantage before accepting it as real.

Reading Dr. Eades' blog entry (proteinpower.com) today provided some enlightening information on the subject. There are interesting quotes from previous posts, describing the metabolic processes that might lead to the metabolic advantage.

The post also mentions this Nutrition Journal paper by Feinman and Fine: "A calorie is a calorie" violates the second law of thermodynamics which attempts to account for the metabolic effects that would create the metabolic advantage. A response to that paper (at http://www.ajcn.org/cgi/content/full/80/5/1446) lends some support but reports observational differences, claiming that the measured differences are less than expected.

So, science is starting to look for thermodynamic models that can explain the metabolic advantage. This should be very interesting!