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肥胖悖论:胖人可能更健康

更新时间:2020-3-9 18:40:27 来源:本站原创 作者:佚名 浏览:

In ‘Obesity Paradox,’ Thinner May Mean Sicker
肥胖悖论:胖人可能更健康

A few years ago, Mercedes Carnethon, a diabetes researcher at the Feinberg School of Medicine at Northwestern University, found herself pondering a conundrum. Obesity is the primary risk factor for Type 2 diabetes, yet sizable numbers of normal-weight people also develop the disease. Why?

几年前,美国西北大学(Northwestern University)芬堡医学院(Feinberg School of Medicine)的研究人员梅赛德丝·卡尼索恩(Mercedes Carnethon)遇到了一个难解之谜:肥胖是II型糖尿病最主要的风险因素,然而相当数量体重正常的人也罹患这种疾病。这是为什么?

In research conducted to answer that question, Dr. Carnethon discovered something even more puzzling: Diabetes patients of normal weight are twice as likely to die as those who are overweight or obese. That finding makes diabetes the latest example of a medical phenomenon that mystifies scientists. They call it the obesity paradox.

为了回答这个问题,卡尼索恩博士进行了研究,然而在这些研究中,她发现了更令人费解的事情:正常体重的糖尿病患者的死亡率有可能是那些超重或者肥胖的糖尿病患者的两倍。这一发现结果使得糖尿病成为令科学家们困惑不解的医学现象的最新例证。他们称这种奇怪的现象为肥胖悖论。

In study after study, overweight and moderately obese patients with certain chronic diseases often live longer and fare better than normal-weight patients with the same ailments. The accumulation of evidence is inspiring some experts to re-examine long-held assumptions about the association between body fat and disease.

一项又一项研究发现,患有同样慢性疾病的超重和中度肥胖病人一般都比有同样疾病的正常体重的病人活得更长久、质量也更高。越来越多的证据激发了一些专家对体脂和疾病之间的关系进行重新研究,长期以来人们假设体脂是很多疾病的原因。

Dr. Carl Lavie, medical director of cardiac rehabilitation and prevention at the John Ochsner Heart and Vascular Institute in New Orleans, was one of the first researchers to document the obesity paradox, among patients with heart failure in 2002. He spent more than a year trying to get a journal to publish his findings.

新奥尔良约翰·奥克斯纳心血管研究所(John Ochsner Heart and Vascular Institute)负责心血管康复和预防的医务主任卡尔·拉维(Carl Lavie)博士是第一批记录肥胖悖论的研究人员之一,2002年,他在心脏衰竭的病人中发现了这一现象。拉维花费了一年多的时间来说服一份期刊发表自己的研究结果。

“People thought there was something wrong with the data,” he recalled. “They said, ‘If obesity is bad for heart disease, how could this possibly be true?’ ”

“人们以为那些数据有问题,”他回忆说:“他们说,‘如果肥胖对心脏病不利,这些数据又怎么可能是正确的?’”

But there were hints everywhere. One study found that heavier dialysis patients had a lower chance of dying than those whose were of normal weight or underweight. Overweight patients with coronary disease fared better than those who were thinner in another study; mild to severe obesity posed no additional mortality risks.

但是,到处都能找到这条悖论的蛛丝马迹。一项研究发现,超重的透析患者的死亡概率要低于体重正常或者体重过轻的病人。而在另一项研究中,超重的冠状动脉疾病病人比那些瘦弱的病人生存率更高;轻度到重度肥胖都没有带来额外的死亡风险。

In 2007, a study of 11,000 Canadians over more than a decade found that those who were overweight had the lowest chance of dying from any cause.

2007年,一项持续超过10年、以1.1万加拿大人为研究对象的研究发现,不管死于任何疾病,肥胖人士的死亡率都是最低的。

To date, scientists have documented these findings in patients with heart failure, heart disease, stroke, kidney disease, high blood pressure — and now diabetes.

迄今为止,科学家们已经将心脏衰竭、心脏病、脑中风、肾脏疾病、高血压患者的研究结果记录在案——现在是糖尿病了。

Experts are searching for explanations. One idea is that once a chronic disease develops, the body becomes catabolic, meaning it needs higher energy and caloric reserves than usual. If patients do not have those reserves, they may become malnourished even though their weight is normal, said Dr. Gregg Fonarow, one of the directors of the preventive cardiology program at the University of California, Los Angeles.

专家们在寻求答案。一种观点是,一旦人体出现了慢性疾病,新陈代谢随之加快,意味着需要比往常更多的能量和热量储备。加州大学洛杉矶分校(University of California, Los Angeles)心脏病预防项目主任之一格雷格·佛纳罗(Gregg Fonarow)博士介绍说,如果患者没有这些储备,即使体重正常,也可能营养不良。

Some researchers suspect genetics: Maybe thin people who develop diabetes, cardiovascular disease and other chronic ailments have gene variants that make them more susceptible to these illnesses and put them at greater risk once they become ill. Heart disease in thin people may represent a different illness from heart disease in heavier people, Dr. Lavie said.

一些研究人员怀疑可能是遗传学的原因:也许罹患糖尿病、心血管疾病以及其他慢性疾病的瘦人,他们本身携带了易于患病的基因变异,而患病后这些基因变异使他们需要面对更大的风险。拉维博士说,瘦人的心脏病和胖人的心脏病有可能是截然不同的两回事。

It may be that doctors do not treat thin patients as aggressively as they do heavier patients — or that the yardstick itself is to blame. Most researchers assess obesity by measuring body mass index, a simple ratio of height and weight. But B.M.I. does not take into account body fat, lean muscle mass, metabolic abnormalities and other nuances of physical composition.

也许是因为医生们在治疗瘦患者时不像他们治疗胖患者时力度那么大——或者就是测量指数本身的问题。大多数研究人员通过测量体重指数(BMI,是国际统一使用的肥胖分型标准,计算方法是体重(公斤)/身高(米)的平方,男性大于24,女性大于22为超重——译注)来评估是否肥胖,而BMI就是简单计算身高和体重的比例,没有把体脂含量、肌肉比例、代谢异常以及其他身体构成的细微差别考虑进去。

Perhaps, some experts say, we are not asking the right question in the first place. Maybe we are so used to framing health issues in terms of obesity that we are overlooking other potential causes of disease.

还有一些专家说,或许我们一开始就没有发现真正的问题所在。或许我们太习惯于把健康问题归罪于肥胖,从而忽视了其他潜在的致病原因。

Dr. Neil Ruderman, an endocrinologist at Boston University School of Medicine, was the first to identify a condition he called “metabolically obese normal weight,” in 1981. Such people have weights in the normal range on the B.M.I. chart but also have metabolic abnormalities, including high levels of insulin resistance and triglycerides; they tend to carry fat around the middle, which is more apt to affect the heart, liver and other organs than fat in the hips and thighs.

尼尔·鲁德尔曼(Neil Ruderman)博士是波士顿大学医学院(Boston University School of Medicine)的内分泌学专家,1981年他第一次明确了一种现象,他称之为“正常体重代谢性肥胖”(metabolically obese normal weight)。表现出这种症状的病人在BMI图表上的体重处在正常值范围内,但却存在着新陈代谢异常,包括高胰岛素抗性和高甘油三酯;他们腰间往往像套了个救生圈,相比那些脂肪囤积在臀部和大腿的人来说,这种情况更容易影响心脏、肝脏还有其他器官。

“If we’re open-minded when we look at the data, we often find confounding factors that can explain the disease associations we blame on weight,” said Linda Bacon, a nutrition professor at City College of San Francisco and author of “Health at Every Size: The Surprising Truth About Your Weight.”

“如果在研究这些数据时候心态更加开放,往往会发现那些被我们归咎于体重的疾病,是有着其他易于混淆的因素可以解释的,”旧金山市立学院(City College of San Francisco)营养学教授琳达·培根(Linda Bacon)说。她也是《各种体型的健康:关于体重的惊人真相》(Health at Every Size: The Surprising Truth About Your Weight)一书的作者。

Fitness is an important, and often unmeasured, confounder, and the growing pile of paradoxical evidence is forcing experts to re-evaluate its importance.

身体体质是一个重要的、而且一般不可测量的干扰变量,然而越来越多自相矛盾的证据迫使专家们去重新衡量它的重要性。

The link between obesity and health derives in part from research like the Framingham Heart Study, which has followed thousands of men and women since the 1940s. But Paul McAuley, a professor of health education at Winston-Salem State University, has noted that Framingham and other longitudinal studies often fail to take into account physical activity and fitness.

肥胖和健康之间的联系,部分源自像弗莱明汉心脏研究所(Framingham Heart Study)这种机构提供的研究报告,该研究所从20世纪40年代开始跟踪调查数以千计的男性和女性。但是,温斯顿—塞伦州立大学(Winston-Salem State University)健康教育学教授保罗·麦考利(Paul McAuley)指出,弗莱明汉的相关研究和其他纵贯性研究(longitudinal studies),往往没有将人们的体力活动和体质考虑进去。

Research that does tease apart weight and fitness — like a series of studies conducted by Steven Blair at the Cooper Institute in Dallas — shows that being fat and fit is better, healthwise, than being thin and unfit. Regular aerobic exercise may not lead to weight loss, but it does reduce fat in the liver, where it may do the most metabolic damage, according to a recent study at the University of Sydney.

有些研究确实把体重和体质区分开来——达拉斯库珀研究院(Cooper Institute)的史蒂夫·布莱尔(Steven Blair)所做的系列研究正是其中之一——他的研究表明,从健康角度来说,身材胖但体质好,比身材瘦但羸弱要更好。悉尼大学(University of Sydney)最近的一项研究表明,定期的有氧运动可能不会让体重变轻,但是确实能够减少肝脏里的脂肪,那是最有可能发生代谢异常的器官。

“More often than not, cardiovascular fitness is a far more important predictor of mortality risk than just knowing what you weigh,” said Glenn Gaesser, author of “Big Fat Lies” and director of the Healthy Lifestyles Research Center at Arizona State University.

“多数情况下,保持心血管健康远比仅仅知道自己的体重更能预测死亡风险,”《大谎言》(Big Fat Lies)作者、亚利桑那州立大学(Arizona State University)健康生活研究中心(Healthy Lifestyles Research Center)主任格伦·加瑟尔(Glenn Gaesser)说。

In 2005, an epidemiologist, Katherine Flegal, analyzed data from the National Health and Nutrition Examination Survey and found that the biggest risks of death were associated with being at either end of the spectrum — underweight or severely obese. The lowest mortality risks were among those in the overweight category (B.M.I.s of 25 to 30), while moderate obesity (30 to 35) offered no more risk than being in the normal-weight category.

2005年,流行病学家凯瑟琳·弗莱戈(Katherine Flegal)分析了美国国家健康与营养调查(National Health and Nutrition Examination Survey)的数据,发现死亡风险最大的人群是那些位于体重两端的人们——体重过轻或者严重肥胖。死亡风险最低的人群是超重人士(BMI值在25-30之间),而中度肥胖者(30-35)和正常体重范围的人死亡风险一样高。

Whatever the explanation for the obesity paradox turns out to be, most experts agree that the data cast an uncertain light on the role of body fat. “Maintaining fitness is good and maintaining low weight is good,” Dr. Lavie said. “But if you had to go off one, it looks like it’s more important to maintain your fitness than your leanness. Fitness looks a little bit more protective.”

不管最后如何解释肥胖悖论,大多数专家都认同,这些数据对体脂率产生的作用提出了质疑。 “保持健壮的体魄和维持较轻的体重都是有益的,”拉维博士说:“但是如果你不得不放弃其中之一,似乎保持健壮比骨瘦如柴更重要。健壮的体质更具有保护性。”

That is a message that may take a long time to reach your family physician, however. “Paradigm shifts take time,” Ms. Bacon said. “They also take courage. Not many people are willing to challenge the weight conventions. They’re just too culturally embedded, and the risk of going against convention is too high.”

然而,这个信息可能需要很长时间才能被你的家庭医生接受。“范式的转变需要时间, 也需要勇气。不是很多人愿意质疑关于体重的传统看法。这一看法在文化上太根深蒂固,而挑战传统又是冒天下之大不韪。” 培根说。

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