研究生科技英语阅读课文翻译对照(40)

近几年来，科学将我们迫不及待要吃的食欲跟基因和激素联系起来。激起这些强烈的欲望的激素有胃促生长素和消瘦素，也被称作“饥饿激素”。胃促生长素主要由胃保护层的细胞产生。它的职责是影响控制新陈代谢的下丘脑，让你感到饥饿。当节食者减肥并且努力维持减肥效果，他的胃促生长素水平就会升高。就像他们的身体要试图恢复失去的脂肪。这是为什么很难减肥并维持减肥效果的原因之一。
Leptin turns your appetite off and is made by fat cells. Low leptin levels increase your appetite and signal your body to store more fat. High leptin levels relay the opposite signal. Many obese people have developed a resistance to the appetite-suppressing effects of leptin and never feel satisfied, no matter how much they eat. Basically, your body uses these hormones to help you stay at your weight and keep you from losing fat — which is another reason why dieting can be so difficult.
消瘦素消除你的食欲，它来自脂肪细胞。低消瘦素水平增加你的食欲并通知你的身体储存更多的脂肪。高消瘦素水平传递相反的信号。很多肥胖的人已经形成了一种对消瘦素抑制食欲效应的抵抗，不管他们吃多少也从不感到满足。从根本上说，你的身体利用这些激素帮助你保持现在的体重，不让你的脂肪流走——这是节食如此之难的另外一个原因。
Lack of sleep promotes obesity by messing with these hunger hormones. If you skimp on sleep, ghrelin levels rise, making you hungry, and leptin levels dip, which signals a need for calories. During my internship, I was chronically sleep-deprived because I had to be at the hospital and stay up all night every third night. I gained a lot of weight that year; now I know why. Years later, after I gave birth to my son Alex, I put on a lot of pounds, too — twenty pounds left over from the pregnancy, and twenty pounds from being up all night with him. He had colic (fussiness) and never slept more than twenty minutes at a time the first six months of his life. My weight started coming off more easily when I got more sleep.