What about the cravings that many pregnant women experience? Growing research suggests that odd food yearnings--and food aversions--may protect the fetus. Some pregnant women lose the desire to drink coffee or wine and turn green at the sight of fish, meat, eggs or vegetables. Instead, they crave sweets, fruits (especially citrus) and dairy products.

　　如何解释很多孕妇对某些食物的偏好呢？越来越多的研究表明对一些奇怪食物的偏好——和厌恶——可能是出于保护胎儿的缘故。有些孕妇不再爱喝咖啡或红酒，并且一看到鱼、肉、蛋或蔬菜就倒胃口。但是，她们却变得爱吃甜食、水果(尤其柑橘)和奶制品。

　　One explanation: These foods are least likely to carry harmful organisms or natural toxins. "It may be your body is telling you to keep your fetus away from anything that might be toxic," says Frances Largeman, managing editor of FoodFit.com, a website promoting healthy eating habits.

　　有一种解释：这些食物中含有害微生物或天然毒素的可能性最小。"可能是你的身体在教你避免使胎儿接触可能有毒的食物，"致力于宣传健康饮食习惯的FoodFit.com网站主编Frances Largeman说。

　　Largeman acknowledges that the theory doesn't account for why some pregnant women hunger for pickles and others for apple strudel. Cravings are difficult to explain scientifically, she says, "because people don't eat nutrients; they eat food." And everybody's preferences differ.

　　Largeman承认该理论无法解释为什么有些孕妇爱吃泡菜，有些爱吃苹果馅饼。吃的渴望很难从科学上解释，她说。"因为人们不是吃营养，而是吃食物。"而各人偏好又是千差万别。

　　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.

　　某些吃的渴望在人类生存和进化中曾经起到了重要作用。几十万年以前，

脂肪和糖是很缺乏的，而脂肪是热量的重要来源(每克脂肪提供的卡路里是蛋白质或淀粉的两倍多)，因此我们的祖先在当时并不需要控制脂肪的摄入量。相反，当他们发现富含脂肪的食物时，他们有多少吃多少，并练就了一种无限储存过多热量的能力。

　　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.

　　这种对脂肪和糖的渴望现已在我们的大脑中固定下来，大脑受到包括内啡素的十几种化学物质的控制。譬如血清素是产生"好的感觉"的化学物质。当它的含量降低时，我们似乎就会渴望糖和碳水化合物，因为它们能提高血清素含量并改善情绪。这一点也许有助于解释为什么很多女性在经期前后会想吃巧克力。

　　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."

　　有些专家认为吃的渴望除了能反映我们生理冲动以外，还能反映我们社会和心理构成。"食物给我们生活带来慰藉，"美国饮食协会发言人Jeff Hampl说。"吃的渴望常常与童年某段经历以及与此相关的美好情感有联系。人的潜意识渴望恢复这种情感。"

　　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."

　　这也许能解释为何我会对迷迭香情有独衷，这是因为我妈妈在每个感恩节都会做这道菜。不过，不论原因如何，有时会渴望鮭肉的Largeman认为，当这种渴望出现时，你都应该去满足它。"渴望通常只会愈演愈烈，"她说，"它会导致暴饮暴食。"

　　But most of us long for foods that aren't as nutritious as salmon. What should we do?

　　但是大多数人所渴望的食物不及鲑肉营养丰富。我们应该怎么做呢？

　　First, make sure you're experiencing a true craving--not just plain old hunger or thirst. "Sometimes people don't realize they're physically hungry," says O'Neil."If it's actually hunger, eating something reasonable such as a piece of fruit rather than a chocolate bar might do the trick."

　　首先，必须确定你正经历一种真正的渴望——而不是普通饥渴。“有时，人们意识不到自己身体正处于饥饿状态，”O'Neil说。“如果真是饥饿的话，那么选择合理的食物，譬如一片水果而不是一块巧克力，就可以奏效。”

　　Another option, he says, is to"leave the scene of the craving. Change your setting and engage in other things that don't involve food."

　　另一个办法，他说，是“离开想吃东西的场所。改变一下环境，做一些与吃无关的事情。”

　　Finally, if your craving just won't be rebuffed, indulge it--judiciously."If you have a salty craving," says Largeman, "it's better to buy a single-serving bag of salt-and-vinegar chips than to buy a large bag and keep it around the house." Or try a less potent alternative--say, low-fat chocolate milk or a frozen fudge pop rather than a slab of fudge.

　　最后，如果你实在无法打消吃的渴望，那么就放纵自己吧——不过要适度。"如果你爱吃咸食，"Largeman说，"那么买一袋一人吃的咸醋味薯片要比买一大袋放在家里好。"或者还可以选择一个低热量的品种——譬如低脂巧克力牛奶或一瓶冰冻的乳脂软糖汽水而不是一大块乳脂软糖。

　　For years, Catherine Monk would ignore her sweet tooth, then splurge on half a pint of ice cream. Now wiser, she settles for a few table-spoons every night."That does it for me," she says.

　　几年来，Catherine Monk一直克制自己对甜食的渴望，压制不了时，就无节制地吃半品脱冰淇淋。现在，她变聪明多了，每晚只允许自己吃上几勺。"这对我很有效，"她说。