What are Calories Part 2

So last time, in the guise of addressing the emails of an Internet crazy person and his assertion (so far as I can tell) that since calories are not an actual physical thing, the calorie model of body weight is not valid.  I addressed a ton of different issues related to the concepts of calories.  This included what they are, how they are measured, some serious pedantry regarding vocabulary and what they ultimately represent.  The overall summary of what I wrote there is that while it is true that calories are not a physical entity (i.e. I can’t hand you a bottle of calories), they are valid in that they represent a defined measurable quantity (the generation of heat) related to how something that is real (i.e. food or nutrients) is metabolized within the body.

Basically calories, like other concepts such as watts or horsepower, are a semantic proxy for something that does exist.  And while our language is imprecise it is the height of semantic stupidity to dismiss the concept based on that imprecise language.  No, we do not “eat” calories, we eat food.  Said food being metabolized in such a way as to produce heat which can be measured and defined in terms of calories.

So what does this all mean in terms of the calorie or energy balance model of bodyweight?  Well, that’s what I want to talk about today.  Some of this will tread the same ground as my article on Energy Balance and I’ll try to only summarize some of those concepts since the details can be found there.

Calorie/Energy Balance: Part 1

At the most basic level, we often talk about calorie balance which represents the difference between calorie intake (from food) and calorie expenditure (from a variety of components such as Resting Metabolic Rate, Activity and others).  If calorie intake exceeds calorie expenditure, we gain weight/fat (I’ll explain this momentarily).  If calorie intake matches calorie expenditure, no change occurs.  If calorie intake is lower than calorie expenditure we lose weight.   More technically we state that

Calorie Expenditure – Calorie Intake = The Change in the Energy Stored in the Body