Researchers have found that people (and animals) presented with large portions will eat up to 30 percent more than they could otherwise. Human appetite, it turns out, is surprisingly elastic, which makes excellent evolutionary sense: It behooved our hunter gatherer ancestors to feast whenever the opportunity presented itself, allowing them to build up reserves of fat against future famine.
Michael Pollan, The Omnivore's Dilemma: A Natural History of Four Meals
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