"A calorie is a calorie" violates the second law of thermodynamics

I thought that "Richard Feinman" was just a misspelling of Richard Feynman, then I noticed the dates. That would be just like him to author something like this though.

tl;dr version:

Calories derived from fat vs protein vs carbohydrates have different inefficiencies in converting them from their theoretical caloric value to their useful work in the body.

Fat is the most efficient with a loss of just @ 2-3%, carbs are at 6-8%, protein 25-30%. [edit Most of] this loss is in the form of heat.

It was not mentioned why this excess heat would not simply be offset by the body avoiding the normal processes it takes to maintain body temperature. Presumably the body generates enough heat as a by-product at room temperature and thus there is nothing the body can back off of to make use of the waste heat described above.

FTA:

> Some of the available energy is lost as heat and in the internal rearrangement of chemical compounds and other changes in entropy.

So not all of the difference in efficiency is made up in the form of heat. Unfortunately, I don't remember enough biochemistry nor thermodynamics to dive deeper into this, but I think this article is a good starting point for a discussions, which has otherwise just been dismissed with the "a calorie is a calorie" argument.

Results will, apparently, vary. Your metabolism may be blessed as vinegar reactive. Timothy Ferris used a glucose meter to try and track impact of Vinegar on the GI, and didn't get positive results:

http://bodezfitness.com/blog/tasso/post.cfm/post/4841/2-pre-...