Interesting article. The Atwood system does make an adjustment for the metabilized energy as a fraction of combustion energy. For carbs, it 85%, I'm not sure about fat and protein. It is certainly plausible that it could vary between 75% and 95% depending on how food is prepared. Of course, this uncertainy makes the 0.1% fuss over which calorie look silly. This ±10% uncertainty has nothing to do with whether the energy is measured in kilojoules or kilocalories. Even Atwood recognized that different carbs for example had different energy content, but the world certainly gravitated to his simplest method in which only carbs, proteins, fats (and alcohol) exist with an energy content for each. I guess the guy is making two points: *Lets use the complicated version of Atwood *Lets update the factors for "how cooked" and make it MORE complex. Basically the Atwood system ignores or oversimplifies interaction and assumes the whole is the sum of its parts. BTW, none of my argument is a proposal the calorie should continue. We should migrate to the joule for ALL forms of energy. The calorie had its place (which is now over) and I don't consider it the unmitigated evil you make it out to be.
--- On Wed, 7/22/09, Pat Naughtin <[email protected]> wrote: From: Pat Naughtin <[email protected]> Subject: [USMA:45439] Re: Names of old measuring methods To: "U.S. Metric Association" <[email protected]> Date: Wednesday, July 22, 2009, 2:04 AM In this respect I find appalling the use of the word calorie as if it had a definite definition and its active promotion by folk who should know better. See http://www.newscientist.com/article/mg20327171.200-the-calorie-delusion-why-food-labels-are-wrong.html?page=1 for a recent example in what should be a leading science magazine. By the way, in this article, W. O. Atwater is treated with more hindsight than kindness. On your point that the variation between all the different calories is only about 0.1 %, I made the following calculation. This could add to something like a 100 grams of fat over the course of a year. I base this on a 10 000 kilojoule per day requirement for an average male. As 0.1 % of this is 10 kilojoules per day, or 3650 extra kilojoules of food energy each year. I then applied the 'Atwater factor' of 37 kilojoules per gram for fat to arrive approximately at the calculated 100 grams of fat.
