http://www.sina.com.cn 2008年11月13日 09:33
Certain cravings were central to human survival and evolution. Fat and sugar were scarce hundreds of thousands of years ago. Fat was a precious source of calories (supplying more than twice the calories per gram of either protein or starch), and our ancestors had no need to develop an appetite shutoff valve for fat. Instead, when they found fatty food, they ate all they could get and developed an unlimited capacity to store extra calories.
The quest for fat and sugar is now hardwired into our brains, governed by dozens of chemicals including endorphins. Serotonin, for example, is the "feel good" chemical. When levels are low, we seem to crave sweets and carbs, which raise serotonin and improve mood. This may help explain why many women crave chocolate near their periods.
Some experts think cravings are as much a reflection of our social and psychological makeup as they are of our physiological impulses. "Food adds solace to our lives," says Jeff Hampl, a spokesman for the American Dietetic Association. "Often, cravings are tied to a childhood experience and good feelings associated with it. There's a subconscious desire to replace those emotions."
This would explain my predilection for rapini, since my mother serves it every Thanksgiving. Yet regardless of the reason, Largeman--who craves salmon sometimes--thinks you should satisfy a craving when it strikes. "A craving usually just gets worse," She says,"and it could lead to binging."