Calorie recount

Press, Volume CXI, Issue 32663, 20 July 1971, Page 12

Calorie recount

Some readers of yesterday’s editorial "Calorie count” may have been sur prised to learn that the 3290 calories used up by an average New Zealander each day would barely be sufficient to boil the water for one cup of tea. In fact, a person who became a human tea urn would generate enough heat each day to make more than 200 cups of tea. The error, which was corrected in some editions of the paper, arose from confusion between two quite different definitions of calorie, the unit of heat measurement. A “gram calorie,” a term used in physics, is the small amount of heat required to raise one gram of water one degree Celsius in temperature. This unit has proved to be too small to be of practical use in physiology and in matters of diet a Calorie (sometimes spelt with a capital letter) is one thousand times larger: the amount of (heat needed to raise one kilogram (more than 21b) of water one degree Celsius in temperature.

As one correspondent who drew attention yesterday to the mistake pointed out, 3290 gram calories a day would barely be enough to keep a sparrow alive. Humans are a thousand times more energetic than that and the heat they use up in a day would boil about nine gallons of cold water.