Over the past 70 years, ultra-processed foods have come to dominate the U.S. diet. 

在過去的70年里，精加工食品已經主導了美國人的飲食,。

These are foods made from cheap industrial ingredients and engineered to be super-tasty and generally high in fat, sugar and salt.

這些食品由廉價的工業(yè)原料制成，經過加工后超級美味,，通常富含脂肪,、糖和鹽。

The rise of ultra-processed foods has coincided with growing rates of obesity, leading many to suspect that they've played a big role in our growing waistlines. 

隨著精加工食品的興起,，肥胖率也在不斷上升,，許多人開始懷疑，這些食品在我們日益增長的腰圍中扮演了重要角色,。

But is it something about the highly processed nature of these foods itself that drives people to overeat? 

但是,，真的是這些食物本身的高度加工性質導致人們吃得過多嗎?

A new study finds the answer is yes.

一項新的研究發(fā)現(xiàn)答案是肯定的。

The study, conducted by researchers at the National Institutes of Health, is the first randomized, controlled trial to show that eating a diet made up of ultra-processed foods actually drives people to overeat and gain weight compared with a diet made up of whole or minimally processed foods. 

這項由美國國立衛(wèi)生研究院的研究人員進行的研究,，是第一項隨機對照試驗,，它表明，與完全無加工或最低加工食品構成的飲食相比,，食用由精加工食品構成的飲食實際上會導致人們吃得過多,，體重增加。

Study participants on the ultra-processed diet ate an average of 508 calories more per day and ended up gaining an average of 2 pounds over a two-week period. 

精加工飲食的研究參與者平均每天多攝入508卡路里,，在兩周的時間里平均增重2磅,。

People on the unprocessed diet, meanwhile, ended up losing about 2 pounds on average over a two-week period.

與此同時，未加工飲食的人在兩周內平均減掉了2磅,。

"The difference in weight gain for one [group] and weight loss for the other during these two periods is phenomenal.We haven't seen anything like this," says Barry Popkin, a nutrition professor at the University of North Carolina who has studied the role of ultra-processed foods in the American diet but was not involved in the current research.

“在這兩個時期,，一組人的體重增加和另一組人的體重下降的差異是顯著的。北卡羅來納大學營養(yǎng)學教授巴里·波普金表示,，波普金研究過精加工食品在美國飲食中的作用,，但沒有參與此次研究。

Dariush Mozaffarian, dean of Tufts University's Friedman School of Nutrition Science and Policy, agrees that the findings are striking. 

塔夫茨大學弗里德曼營養(yǎng)科學與政策學院院長達里烏什·莫扎法里安也認為,，這些發(fā)現(xiàn)令人震驚,。

He says what was so impressive was that the NIH researchers documented this weight gain even though each meal offered on the two different diets contained the same total amount of calories, fats, protein, sugar, salt, carbohydrates and fiber. 

他說，讓人印象深刻的是,，美國國立衛(wèi)生研究院的研究人員記錄下了這一體重增加現(xiàn)象,，盡管兩種不同飲食提供的每頓飯包含相同的總熱量,、脂肪、蛋白質,、糖,、鹽、碳水化合物和纖維,。

Study participants were allowed to eat as much or as little as they wanted but ended up eating way more of the ultra-processed meals, even though they didn't rate those meals as being tastier than the unprocessed meals.

研究參與者被允許想吃多少就吃多少,，但最終吃得更多的是精加工食品，盡管他們并不認為這些食品比未經加工的食品更美味,。

"These are landmark findings that the processing of the foods makes a huge difference in how much a person eats," says Mozaffarian. 

莫扎法里安說:“這些具有里程碑意義的發(fā)現(xiàn)表明，食物的加工過程對一個人的食量有很大影響,?！?/p>

That's important, because the majority of foods now sold in the U.S. — and increasingly, around the globe — are ultra-processed.

這一點很重要，因為現(xiàn)在在美國銷售的大多數(shù)食品都是精加工食品,，而且—在全球范圍內—越來越多,。

Another interesting finding: Both groups ate about the same amount of protein, but those on the ultra-processed diet ate a lot more carbs and fat. 

另一個有趣的發(fā)現(xiàn)是:兩組人攝入的蛋白質量大致相同，但那些采用精加工飲食的人攝入的碳水化合物和脂肪要多得多,。

There is a concept, called the protein leverage hypothesis, that suggests that people will eat until they've met their protein needs. 

有一個概念,，叫做蛋白質杠桿假說，它表明人們會一直吃東西直到他們滿足了蛋白質的需求,。

Hall says that this seems to be the case in this study and it partially explains the difference in calorie consumption they found. 

霍爾說,，在這項研究中，情況似乎就是這樣,，這部分解釋了他們發(fā)現(xiàn)的卡路里攝入量的差異,。

Even though the meals were matched for calories and nutrients, including protein, the ultra-processed meals were more calorie dense per bite.

盡管每頓飯的卡路里和營養(yǎng)成分(包括蛋白質)是相匹配的，但每一口經過超級加工的飯的卡路里密度更高,。

In part, that's because ultra-processed foods tend to be low in fiber, so researchers had to add fiber to the beverages served as part of these meals to match the fiber content of the unprocessed diet. 

部分原因是,，精加工食品的纖維含量往往較低，因此研究人員不得不在這些膳食的飲料中添加纖維,，以匹配未加工食品的纖維含量,。

That means participants on the ultra-processed diet might have had to munch through more carbs and fat to hit their protein needs.

這意味著采用精加工飲食的參與者可能不得不咀嚼更多的碳水化合物和脂肪來滿足他們對蛋白質的需求。

And one last finding of note: People ate much faster — both in terms of grams per minute and calories per minute — on the ultra-processed diet. 

最后一個值得注意的發(fā)現(xiàn)是:在超加工飲食中,，人們吃得更快——無論是每分鐘的克數(shù)還是每分鐘的卡路里數(shù),。

Hall says it might be that, because the ultra-processed foods tended to be softer and easier to chew, people devoured them more quickly, so they didn't give their gastrointestinal tracts enough time to signal to their brains that they were full and ended up overeating.

霍爾說，這可能是因為,，由于超加工食品往往更軟,、更容易咀嚼，人們會更快地吃掉它們,，所以他們沒有給自己的胃腸道足夠的時間向大腦發(fā)出信號,，表明自己已經吃飽了,，最終就會吃得過多。

Hall says his findings have implications for the diet wars — vegan versus low-carb or low-fat diets. 

霍爾說,，他的發(fā)現(xiàn)對素食主義與低碳水化合物或低脂肪飲食之間的飲食戰(zhàn)爭具有啟示意義,。

"They all have something in common. ... Proponents of healthy versions of those diets suggest that people cut out ultra-processed foods." 

“他們都有一些共同點...健康飲食的支持者建議人們少吃精加工食品?！?/p>

He says that this elimination might account for at least part of the success that people have on these diets.

他說,，這種減少可能至少是人們在這些飲食上取得成功的部分原因。

Popkin says the take-home message for consumers is, "We should try to eat as much real food as we can. That can be plant food. It can be animal food. It can be [unprocessed] beef, pork, chicken, fish or vegetables and fruits. And one has to be very careful once one begins to go into other kinds of food."

波普金說,，對消費者來說,，最重要的是，“我們應該盡可能多吃真正的食物,?？梢允侵参镄允澄铩,？梢允莿游锸澄?。它可以是(未經加工的)牛肉、豬肉,、雞肉,、魚或蔬菜和水果。一旦你開始吃其他種類的食物,，你就必須非常小心,。”

But Popkin says the findings also present a challenge for the global food industry: how to preserve the convenience, abundance and low cost of food without sacrificing health. 

但是波普金說,，這些發(fā)現(xiàn)也給全球食品工業(yè)提出了一個挑戰(zhàn):如何在不犧牲健康的前提下保持食品的便捷性,、豐富性和低成本。

"Let's see if they can produce ultra-processed food that's healthy and that won't be so seductive and won't make us eat so much extra," he says.

他說:“讓我們看看他們能否生產出健康,、不那么誘人,、不會讓我們多吃那么多的精加工食品?！?/p>

 "But they haven't yet."

“不過目前他們還沒有,。”