Word: braine
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...always available part of the diet--goes back millions of years. But humanity's appetite for animal fat and protein is probably more recent. It was some 2.5 million years ago that our hominid ancestors developed a taste for meat. The fossil record shows that the human brain became markedly bigger and more complex about the same time. And indeed, according to Katherine Milton, an anthropologist at the University of California, Berkeley, "the incorporation of animal matter into the diet played an absolutely essential role in human evolution...
...appetite for meat didn't mean we lost our passion for sweets, though. As Berkeley's Milton points out, the brain's growth may have been facilitated by abundant animal protein, but the brain operates on glucose, the sugar that serves as the major fuel for cellular function. "The brain drinks glucose 24 hours a day," she says. The sugars in fruit and the carbohydrates in edible grains and tubers are particularly good sources of glucose...
...year--and, under normal circumstances, burns almost exactly that amount. The body achieves that balance by automatically increasing or decreasing the efficiency with which it performs various tasks, thus consuming fewer or more calories. (Most of the calories we expend are used to breathe, maintain body temperature, keep the brain chugging along, etc. Depending on how much you move, physical activity typically accounts for 15% to 30% of the total.) If you pack on a couple of pounds over the course of the year, your body's error rate is still less than...
Accomplishing that feat requires a lot of communication and coordination among the fat cells, the liver, the muscles, the brain, the stomach and the gastrointestinal tract. Sometimes the signal is a molecule. Other signals are actually conducted along nerve paths. There are even mechanical signals, like the stretching of the stomach, which is one way the body says, "I'm full...
...might expect, the short-term signals are involved mostly with the initiation and completion of meals. Ghrelin, a hormone produced by the stomach, tells the brain, "It's time to eat!" When enough food leaves the stomach and reaches the small intestine, another hormone, called cholecystokinin, signals that the meal is over--and triggers the release of enzymes in the gallbladder and the pancreas...