为什么运动不能帮所有人甩掉脂肪

Exercise has innumerable health benefits, but losing weight may not be among them. A provocative new study shows that a substantial number of people who take up an exercise regimen wind up heavier afterward than they were at the start, with the weight gain due mostly to extra fat, not muscle.

运动对健康有数不清的益处，但减肥可能并非其中之一。一项富有挑战意味的新研究表明，很多人在开始执行体育锻炼计划后体重反而有所增加，更糟糕的是，增加的这部分大多是多余的脂肪而不是肌肉。

But the study also finds, for the first time, that one simple strategy may improve people’s odds of actually dropping pounds with exercise.

但也正是这同一项研究首次发现了一种可以切实增加人们运动减肥几率的简单策略。

As we all know, the fundamentals of weight loss should be simple. Burn more calories on any given day than you consume and, over time, you will lose weight. Theoretically, we can achieve that desirable condition by reducing the number of calories that we take in through dieting or by increasing the number of calories that we incinerate through exercise.

我们都知道，减肥的基本原理非常简单。只要你每天消耗的热量多于摄入量，随着时间的推移，你就会越来越瘦。从理论上说，通过节食减少热量摄入或通过运动增加热量消耗都能达到上述理想状况。

But in reality, most people do not achieve or sustain weight loss, no matter what method they try.

但在现实中，大多数人试遍了所有方法，还是没能达到或维持所希望的减肥效果。

Exercise is particularly problematic in this regard. A recent review of studies related to exercise and weight control found that in most of the studies, people lost barely a third as many pounds as would have been expected, given how many calories they were burning during workouts. Many studies also report enormous variations in how people’s waistlines respond to the same exercise program, with some people dropping pounds and others gaining fat.

在这方面，运动的问题尤其大。近期的一项关于运动和体重控制研究的综述发现，在大多数的研究中，人们在运动后的体重减轻量，只有按照锻炼消耗的卡路里数换算出来的预期减重量的三分之一。许多研究还报告，即使执行相同的锻炼计划，不同的人的腰围变化之间也存在巨大差异，一部分人的体重减轻了，另一部分人反倒更胖了。

Scientists have had little understanding, however, of why exercise helps some people but not others to shed pounds or whether there might be early indications of how people will respond to an exercise routine.

但是，对于为什么运动能够帮助某些人甩掉赘肉却对另一些人毫无用处，科学家们仍然没什么头绪，此外，他们也不清楚是否有什么早期指征可以预测，有规律的锻炼对具体的某个人的效果如何。

So for the new study, which was published last month in The Journal of Strength and Conditioning Research, scientists at Arizona State University in Phoenix recruited 81 healthy but sedentary adult women. All of the women were overweight, based on their body mass index, but some were significantly heavier than others. None had exercised regularly in the past year.

上个月，《力量与训练研究杂志》(The Journal of Strength and Conditioning Research)上发表了一项新研究。在这项研究中，位于菲尼克斯的亚利桑那州立大学(Arizona State University)的科学家们招募了81名习惯久坐不动的健康成年女性。根据身体质量指数(B.M.I.)来判断，她们全都超重，但其中一部分人超重更为显著。在过去一年里，她们均未进行过有规律的锻炼。

The women were told that they would be joining a fitness study and would exercise in order to improve their aerobic endurance. The scientists asked the women not to change their eating habits in any way.

科学家们告诉这些受试女性，她们将参加一项以增强有氧耐力为目标的健身研究，并要求她们不要对原来的饮食习惯作出任何改变。

Each of the volunteers visited the physiology lab at the start of the study and the scientists determined their weight, B.M.I., percentage of body fat, current endurance level, and others measures of health and fitness.

在研究开始时，每名志愿者都来到生理实验室，接受了体重、B.M.I.、体脂百分比、当前耐力水平等多种健康和健身指标的测定。

Then each woman began a supervised exercise program designed to be vigorous but manageable by most people, said Glenn Gaesser, a professor of nutrition and health promotion at Arizona State and senior author of the study. The women walked on treadmills at the laboratory three times per week for 30 minutes at a pace that represented about 80 percent of their maximum endurance.

其后，她们开始在监督下执行锻炼计划，而且，据该研究的资深作者、亚利桑那州立大学的营养和健康促进学教授格伦·盖瑟(Glenn Gaesser)称，该计划设计的运动强度很大，但还在大多数人可以接受的范围内。受试女性每周要在实验室的跑步机上完成三次走步锻炼，每次30分钟，且节奏须保持在她们最大耐力80%的水平。

They continued the program for 12 weeks, with the scientists repeating the original fitness and other tests every month during that time.

整个锻炼计划持续了12周，在此期间，科学家们每月都对受试者们进行一次与开始时一样的健身指标复查。

At the end of 12 weeks, the women were all significantly more aerobically fit than they had been at the start. But many were fatter. Almost 70 percent of the women had added at least some fat mass during the program, and several had gained as much as 10 pounds, most of which was from fat, not added muscle.

在第12周结束时，这些女性的有氧能力均比开始时显著改善，但其中有不少人更胖了。在整个研究过程中，有近70%的女性体脂肪量增加，有几个人体重增量达4.5千克，且其中大部分是脂肪而非肌肉的增加。

A few of the women, though, had lost that much fat or more, and quite a few had remained at the same weight as at the start of the regimen.

不过，仍有少数女性减掉了等量甚至更多的脂肪，还有相当一部分女性的体重与研究开始时持平。

At this point, the researchers returned to the data from the first day of the study, to determine whether any obvious differences existed between the women who subsequently gained or lost weight. “Some past studies of dieting had indicated that women who weigh more at the beginning” of a weight-loss program “tend to lose more weight during the program,” Dr. Gaesser said.

这时，研究人员回过头来审视研究第一天时获得的数据，想要确定后来体重增加或减少的女性之间是否存在任何明显的差异。盖瑟博士说：“既往进行的一些有关节食的研究表明”，在减肥计划“开始时体重较重的女性更容易在锻炼期间减肥”。

But the researchers found no correlation in this case between a woman’s weight at the start and end of the study. In fact, the scientists found no connection between any of the original parameters of health and fitness and the women’s responses to the exercise program.

但在该研究中，研究人员们发现受试女性研究开始时与结束时的体重间并没有这种相关性。事实上，科学家们发现，这些女性在研究开始时的任何一项健康和健身参数与锻炼计划对她们的效果都没有关联。

But looking deeper into their data, they discovered one interesting indicator: Those women who were losing weight after four weeks of exercise tended to continue to lose weight, while the others did not.

但随着更加深入地研究数据，他们发现了一个有趣的指征：经过四周的锻炼体重有所减轻的女性在后续的锻炼中往往更容易继续减肥，而在其他人身上则并非如此。

“What that means in practical terms is that someone who wants to lose weight with exercise” should step on the bathroom scale after a month, Dr. Gaesser said. If at that point your weight remains stubbornly unchanged or has increased, “look closely at your diet and other activities,” he said.

“其实际指导意义就是，如果你想要依靠运动减肥，”就应该在锻炼一个月后去浴室里称一称体重，”盖瑟博士说。要是此时你的体重还是不见减轻或者反而更重了，“你就得好好注意下你的饮食和其他活动了。”

While this study didn’t track the women’s eating and movement habits away from the lab, it is likely that those who gained weight began eating more and moving less when they weren’t on the treadmills, “probably without meaning to,” Dr. Gaesser said.

这项研究并没有对受试者们的饮食和实验室之外的运动习惯进行追踪，但盖瑟博士认为，那些在锻炼后体重增加的女性很可能是食量也随之增加了，而且在跑步机锻炼以外的时间里，她们的运动量更少了，“虽然这应该也不是存心的。”

Of course, the study was fairly short-term. It also did not involve men, although some past studies indicate that men, like women, frequently add fat mass after starting to exercise.

当然，这项研究的时间相当短，而且也没有涉及到男性，不过此前有一些研究表明，男性和女性一样经常出现在运动后体脂肪量反而增加的情况。

Still, the results, while sobering in some respects, also provide encouragement. By deploying a bathroom scale and discipline, along with exercise, you may well lose weight, Dr. Gaesser said.

尽管在某些方面，这些研究结果让人觉得减肥大计形势严峻，但它们也为人们指明了希望的方向。盖瑟博士表示，锻炼身体，严格自律，加上一只放在浴室里的体重计，你完全可能实现减肥。

Even more important, the women in the study were much fitter after four months of exercise, and Dr. Gaesser said “fitness matters far more for health than how much you weigh.”

更重要的是，在四个月的锻炼后，参与研究的这些女性的体质都大大改善了。盖瑟博士说：“健身的意义更多地在于让你更健康，而不是单纯地要改变体重的那几个数字。”