Calories: the bane of every dieter. Except, we see how well that’s working for us in the modern U.S. What are calories, and how important are they? Well, here are my thoughts, and I’d love feedback from anyone with something to add.
Calories, technically speaking, are simply a measurement of energy. A ‘calorie’ is the amount of energy required to raise the temperature of one gram of water by one degree Celcius at one atmosphere of pressure–but that’s not exactly what we measure in food. What we use there is a ‘Calorie’ (it must be capitalized), which is the amount of energy required to raise the temperature of one kilogram of water by one degree Celcius. Why are we using the metric system? I don’t know.
But here’s the first obstacle: actual Calories for food are no longer calculated. Instead, existing measurements have been averaged to find the approximate number of Calories per gram of protein, carbohydrate and lipid. So, no matter how carefully you read your packaging, you never know exactly how many Calories are in what you are eating–you only have an approximation.
Close enough, you say? Well, consider that this approximation was arrived at by burning the food. That is, the food was placed in a sealed container, put underwater, and lit on fire to determine how much energy was released (based on how much warmer the surrounding water became). What does that have to do with anything? Well, your body reduces food into digestible pieces through two processes: mechanical digestion and chemical digestion. Mechanical digestion consists of things like chewing and stomach-churning, while chemical digestion consists of things like hydrolysis (the breakdown of protein by acids) and enzyme reactions. This is all completely different from burning; a process chemically known as oxidation. If oxidation is occurring inside your body, you are in trouble.
This means two things: first, we are measuring energy released by the wrong process. That means that Calorie measurements are actually completely meaningless when it comes to nutrition. Second, even if we establish a link between energy released by digestion and energy released by oxidation, we have been measuring energy released from things that your body does not actually store for energy. Fiber, for instance, is indigestible by humans–but burns quite nicely. Likewise protein–which might be used for energy, but is much more likely to be used to repair damaged tissue (something which lipid and carbohydrate cannot do).
Finally, let’s examine the idea that weight gain is caused by excess calorie intake. How many times have we heard that someone is just holding ‘water weight’? Is this different from other weight? No. Yet water contains no Calories. If I ate a pound of sand, would I gain a pound of weight (before I died)? Absolutely. Yet sand contains no Calories.
My conclusion is this: while the measurment of protein, carbohydrate, and lipid grams can be useful, the measurement of Calories in food is absolutely meaningless as far as health or weight control. What is important is how your body will actually interact with the food in question–and that is determined more by the nutrient composition of the food, than by how well it burns.