Eating less can lead to a longer life: massive study in mice shows why
少吃能长寿：
对老鼠的大量研究揭示了原因
Weight loss and metabolic improvements do not explain the longevity benefits of severe dietary restrictions.
减肥和代谢改善并不能解释严格的饮食限制带来的长寿。
Cutting calorie intake can lead to a leaner body—and a longer life, an effect often chalked up to the weight loss and metabolic changes caused by consuming less food. Now, one of the biggest studies of dietary restrictions ever conducted in laboratory animals challenges the conventional wisdom about how dietary restriction boosts longevity.
减少卡路里的摄入可以更瘦——更长寿，这是因为减少食物摄入会减轻体重、促进代谢。现在，一项有史以来在实验室动物身上进行的最大规模的饮食限制研究颠覆了少吃促进长寿的传统观念。
The study, involving nearly 1,000 mice fed low-calorie diets or subjected to regular bouts of fasting, found that such regimens do indeed cause weight loss and related metabolic changes. But other factors—including immune health, genetics and physiological indicators of resiliency—seem to better explain the link between cutting calories and increased lifespan.
这项研究中有近1000只低热量饮食或定期禁食的老鼠，研究发现，这种方案确实会减轻体重、引起代谢变化。但其他因素——包括免疫健康、遗传和恢复能力的生理指标——似乎更能解释减少卡路里与长寿之间的联系。
“The metabolic changes are important,” says Gary Churchill, a mouse geneticist at the Jackson Laboratory in Bar Harbor, Maine, who co-led the study. “But they don’t lead to lifespan extension.”
这项研究的共同负责人、缅因州巴港杰克逊实验室的老鼠遗传学家加里·丘吉尔说：“新陈代谢变化非常重要，但它们不会延长寿命。”
To outside investigators, the results drive home the intricate and individualized nature of the body’s reaction to caloric restriction. “It’s revelatory about the complexity of this intervention,” says James Nelson, a biogerontologist at the University of Texas Health Science Center in San Antonio.
对于外界的研究人员来说，这些结果揭示了人体对热量限制的反应是错综复杂和个性化的。圣安东尼奥德克萨斯大学健康科学中心的生物老年学专家詹姆斯·纳尔逊说：“这揭示了干预的复杂性。”
The study was published today in Nature by Churchill and his co-authors, including scientists at Calico Life Sciences in South San Francisco, California, the anti-ageing focused biotech company that funded the study.
丘吉尔和他的合著者加利福尼亚州南旧金山Calico生命科学公司的科学家们今天在《自然》杂志上发表了这项研究。
Counting calories
计算卡路里
Scientists have long known that caloric restriction, a regimen of long-term limits on food intake, lengthens lifespan in laboratory animals. Some studies have shown that intermittent fasting, which involves short bouts of food deprivation, can also increase longevity.
科学家们很早就知道，长期限制摄入食物的热量可以延长实验动物的寿命。一些研究表明，间歇性禁食，即短时间内不摄入食物也能延长寿命。
To learn more about how such diets work, the researchers monitored the health and longevity of 960 mice, each a genetically distinct individual drawn from a diverse population that mirrors the genetic variability found in humans. Some mice were placed on calorie-limited diets, another group followed intermittent fasting regimens, and others were allowed to eat freely.
为了进一步研究这种饮食的原理，研究人员对960只老鼠的健康和寿命进行了监测，每只老鼠都是从不同的群体中挑选出来的基因独特的个体，这反映了人类的基因变异性。一组老鼠被限制卡路里摄入量，另一组老鼠采用间歇性禁食方案，还有一组可以自由进食。
Cutting calories by 40% yielded the longest longevity bump, but intermittent fasting and less severe calorie restriction also increased average lifespan. The dieting mice also displayed favourable metabolic changes, such as reductions in body fat and blood sugar levels.
减少40%卡路里的老鼠寿命最长，但间歇性禁食和不严格的卡路里限制也延长了老鼠的平均寿命。控制饮食的老鼠代谢较好，如体脂和血糖降低。
However, the effects of dietary restriction on metabolism and lifespan didn’t always change in lockstep. To the authors’ surprise, the mice that lost the most weight on a calorie-limited diet tended to die younger than did animals that lost relatively modest amounts.
然而，饮食限制对新陈代谢和寿命的影响并不总是同步变化的。出乎意料的是，在限制热量饮食中体重减轻最多的老鼠往往比体重减轻相对较少的动物死得更早。
This suggests that processes beyond simple metabolic regulation drive how the body responds to limited-calorie regimes. What mattered most for lengthening lifespan were traits related to immune health and red-blood-cell function. Also key was overall resilience, presumably encoded in the animals’ genes, to the stress of reduced food intake.
这表明，除了简单的代谢调节之外，还有其他过程驱动着身体对限制热量摄入的反应。对延长寿命最重要的是与免疫健康和红细胞功能相关的特征。另一个关键因素是动物基因对食物摄入量减少所带来的压力的整体适应能力。
“The intervention is a stressor,” Churchill explains. The most-resilient animals lost the least weight, maintained immune function and lived longer.
丘吉尔解释说：“干预是一种压力。适应力最强的动物体重减轻最少，免疫功能良好，寿命更长。”
Leanness for longevity
瘦即长寿
The findings could reshape how scientists think about studies of dietary restriction in humans. In one of the most comprehensive clinical trials of a low-calorie diet in healthy, non-obese individuals, researchers found that the intervention helped to dial down metabolic rates—a short-term effect thought to signal longer-term benefits for lifespan.
这些发现可能会改变科学家对人类饮食限制研究的看法。在对健康非肥胖个体进行的全面的低热量饮食临床试验中，研究人员发现，干预有助于降低代谢率——这种短期效应反映了对寿命的长期益处。
But the mouse data from Churchill’s team suggest that metabolic measurements might reflect ‘healthspan’—the period of life spent free from chronic disease and disability—but that other metrics are needed to say whether such ‘anti-ageing’ strategies can truly extend life.
但丘吉尔团队的老鼠数据表明，新陈代谢可以反映“健康寿命”，即没有慢性病和残疾的生命周期，但要判断这种“抗衰老”策略能否真正延长生命，还需要其他指标。
Daniel Belsky, an epidemiologist who studies ageing at the Columbia University Mailman School of Public Health in New York City, cautions against over-extrapolating from mice to humans. But he also acknowledges that the study “adds to the growing understanding we have that healthspan and lifespan are not the same thing”.
纽约市哥伦比亚大学梅尔曼公共卫生学院研究衰老的流行病学家丹尼尔·贝尔斯基说，不要把对老鼠的实验过度推断到人类身上。但他也承认，这项研究“让我们进一步认识到，健康寿命和寿命并不是一回事”。
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