At an event I once attended, Peter Brown mentioned that in the ancient world perceptions about the relation between caloric intake and energy were almost the inverse of those in modern society.

It was one point in a list about how the ancient world would be strange to moderns, but it is one that I have continued to return to over the years, especially when I try dieting.

Modern science identifies calories with energy. In fact, if you look it up, it is defined as a measure of heat energy. And we often think of ourselves as low on energy when we have not eaten. I take it that this is what Brown was talking about. In the ancient world, eating was identified with a loss of energy.

This is one of those interesting situations where it seems to me that common perceptions and science depart (and are probably using different languages, in which energy means two different things). Though there are times when eating can be rejuvenating, the correlation of caloric intake and energy does not work. Eating more does not give you more energy. As anyone who has crashed on the couch after Thanksgiving knows, eating can lead to massive losses of energy.

Of course, the scientist would protest that this is not what they mean by energy. If you don’t work out, the energy you take in when eating is converted to fat, but it’s still energy.

But this has the strange upshot that I am actually weighed down by my energy. The energy suit I wear means I have less energy. And I have to work up the energy to use my energy.

There is definitely something to the ancient inversion of these ideas. To be freed of extra energy is energizing.

Now if I could only channel this into a program that would actually get me to eat less …