Primatologist argues for changes to caloric values listed on food labeling

The current method of calculating caloric content for food is based on a system devised by chemist Wilbur Olin Atwater, over a century ago. He assigned carbohydrates and proteins an average of 4 kilocalories per gram, and fat 9 kilocalories per gram. Because he assumed fiber was passed through the body undigested, no calories were assigned to them. Modern food processors use these simple guidelines to create the caloric values they stamp on packaging. Wrangham says the system is flawed though, because fiber is digested by the body to some extent and thus does provide calories. In addition, he notes that the Atwater system doesn't take into account how much energy the body burns as it digests different foods, which is wrong, because raw food takes more energy to digest than cooked food. The end result, he said, means that customers are relying on labels that could be wrong by as much as 25 percent. Consumers rely on packaging information when making food choices, he noted, and quite often that information is not just misleading, but wrong.

Wrangham's speech was backed up by the head of Leatherhead Food Research, Professor Martin Wickham, who said that changing food labeling to more accurately represent actual caloric content is an urgent issue because it's very important.

Unlike carbohydrates, proteins and fat, fiber, cannot be assigned a single number to calculate how many calories it contains, because different types of fiber have different amounts of calories. Thus, efforts to force food processors to add such labeling would require complex formulations that may or may not be any more accurate than current models. This is because no one has worked out a way to estimate the caloric content of different fibers or to describe how many calories are burned in the process of digesting food. Eating a single serving of raw green beans, for example, should actually count less than eating one that has been cooked. The body has to work harder to process raw foods, which is why dieters turn to them for fast weight loss.

Wrangham concluded his talk by urging food processors to update their calculation methods, though it's doubtful few if any will heed his request without pressure from governmental agencies.

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