I'm actually not convinced that a "calorie is a calorie". Just too much variability in what is done with those different forms of calories once the hit the human ecosystem. sphikes link (the study) and the subsequent links from there are interesting. especially this from one abstract...."Here, we propose that a misunderstanding of the second law accounts for the controversy about the role of macronutrient effect on weight loss and we review some aspects of elementary thermodynamics. We use data in the literature to show that thermogenesis is sufficient to predict metabolic advantage. Whereas homeostasis ensures balance under many conditions, as a general principle, "a calorie is a calorie" violates the second law of thermodynamics."
I know that some consider this a closed discussion, but at least in my mind both possibilities still exist. Could just mean I'm not as well read on this topic as some of you who have made up your minds though.
"dean ornish and dr. davis think the palmitic acid our bodies use for fuel while we sleep is poison if we eat it. zero-carbers like charles washington think the oldest fuel in our evolutionary history – glucose - used by organisms a billion years ago and without which the brains of modern mammals cannot survive for more than a few minutes – is an unnatural toxin if you eat it. both views ignore basic facts of medical physiology and defy evolutionary history." - kurt harris