Jules Hirsch, a research physician at Rockefeller University, conducted a simple but groundbreaking experiment on obesity nearly 50 years ago, changing the way scientists think about fat.

It’s Who You Are, Not What You Eat

王麗娟譯

那年是1959年。紐約洛克斐勒大學研究物理學家朱爾斯‧赫許開始對肥胖族減重感到好奇。他即將展開一項簡單的實驗，從此永遠顛覆科學家對脂肪的認知。

It was 1959. Jules Hirsch, a research physician at Rockefeller University in   New York, had gotten curious about weight loss in the obese. He was about   to start a simple experiment that would change forever the way scientists think   about fat.    

research physician (臨床產品醫師)

他知道肥胖族有巨大的肥胖細胞，細胞內充塞油亮的黃脂。他很好奇，減肥時，這些細胞會有什麼變化。細胞會縮小，還是消失？他決定找出答案，於是針對小胖子或青少年發胖者進行一項研究。在他嚴控實驗對象的飲食幾個月後，所有人都減輕不少體重。

Obese people, he knew, had huge fat cells, stuffed with glistening yellow fat. What happened to those cells when people lost weight, he wondered. Did they shrink or did they go away? He decided to find out by conducting a study of people who had been fat since childhood or adolescence. He strictly controlled what his subjects ate, and over a period of months, all of them lost substantial amounts of weight.   

赫許的原始問題有了答案。實驗對象的脂肪細胞縮小，現在變成正常大小。包括赫許在內的所有人以為，實驗對象出院後將永遠瘦下去。

Dr. Hirsch answered his original question － the subjects’ fat cells had shrunk and were now normal in size. And everyone, including Dr. Hirsch, assumed that the subjects would leave the hospital permanently thinner.   

赫許說，結果「所有人都胖回來。」他心想，或許這些人有著某種根深柢固想胖的心理需求。

Instead, Dr. Hirsch says, “they all regained.” Maybe, he thought, they had some deep-seated psychological need to be fat.  

於是赫許和同事，包括目前在紐約哥倫比亞大學任教的魯道夫‧萊伯博士，反覆做相同的實驗。每次結果都一樣。

So Dr. Hirsch and his colleagues, including Dr. Rudolph L. Leibel, who is now at Columbia University in New York, repeated the experiment and repeated it again. Every time the result was the same.

能為研究結果提出的一種解釋是：人一旦變胖，人體就跟著調適，造成減肥無望並阻隔減肥。但另一組研究證實，這項假設也錯了。

One way to interpret their studies would be to propose that once a person got fat, the body would adjust, making it hopeless to lose weight and keep it off. But another group of studies showed that that hypothesis, too, was wrong.  

這項研究的靈感，來自佛蒙特大學的伊森‧席姆斯。他心想，讓從來沒有體重困擾的瘦子刻意變胖，不知情況會如何。

It began with studies that were the inspiration of Dr. Ethan Sims at the University of Vermont, who asked what would happen if thin people who had never had a weight problem deliberately got fat. 

他的實驗對象是附近一個州立監獄的受刑人，他們志願增重。費了九牛二虎之力，他們成功增重20%到25%，但那是實驗對象花了4到6個月，每天盡可能大吃大喝的成果。

His subjects were prisoners at a nearby state prison who volunteered to gain weight. With great difficulty, they succeeded, increasing their weight by 20 percent to 25 percent. But it took them four to six months, eating as much as they could every day.  

這些人發胖後，新陳代謝跟著提高50%。每一平方公尺的體表面積，至少需要2,700卡路里的熱量，才能維持肥胖，但如果是維持正常體重，每平方公尺僅需1,800卡。

Once the men were fat, their metabolisms increased by 50 percent. They needed more than 2,700 calories per square meter of their body surface to stay fat but needed just 1,800 calories per square meter to maintain their normal weight.  

研究結束時，受刑人並無減重困擾。幾個月後，個個體重恢復正常，而且輕鬆維持。

When the study ended, the prisoners had no trouble losing weight. Within months, they were back to normal and effortlessly stayed there. 

人體的新陳代謝會加速或減緩，將體重保持在一定範圍內。增重時，新陳代謝速度可能快到加倍；減重時，速度可能減為原來的一半。

The body’s metabolism speeds up or slows down to keep weight within a narrow range. Gain weight and the metabolism can as much as double; lose weight and it can slow to half its original speed. 

體重是天生？或者，肥胖只是對這個社會又便宜、又豐富、又誘人的食物，一種幾乎不經意、無意識的反應？

Is body weight inherited, or is obesity more of an inadvertent, almost unconscious response to a society where food is cheap, abundant and tempting?

這個問題的假設是，環境會決定體重，但賓州大學的艾伯特‧史坦卡德博士懷疑，情況果真如此，影響程度會有多大。他研究被領養子女，並在1986年發現，他們和親生父母一樣胖，而他們多胖和領養父母胖瘦無關。

The assumption was that environment determined weight, but Dr. Albert Stunkard of the University of Pennsylvania wondered if that was true and, if so, to what extent. He studied adoptees and in 1986 found they were as fat as their biological parents, and how fat they were had no relation to how fat their adoptive parents were.  

科學家在報告裡總結說：「這項研究的兩大發現是，親生父母的身體質量指數與被領養者的體重分級有關，說明遺傳影響是體脂的重要決定因素；養父母的身體質量指數與被領養者的體重無關，顯示兒時家庭環境因素影響有限或根本毫無影響。」

The scientists summarized it in their paper: “The two major findings of this study were that there was a clear relation between the body-mass index of biologic parents and the weight class of adoptees, suggesting that genetic influences are important determinants of body fatness; and that there was no relation between the body-mass index of adoptive parents and the weight class of adoptees, suggesting that childhood family environment alone has little or no effect.” 

換句話說，肥胖是遺傳使然。

In other words, being fat was an inherited condition.

By GINA KOLATA    

原文參照  http://www.iht.com/articles/2007/05/08/healthscience/snfat.php

【2007-05-21/聯合報/B6版/UNITED DAILY NEWS】