Everyone knows that guy -- the one who can chug more than his fair share of beer, scarf down an entire pepperoni pizza, grab an ice cream, and make a donut run the next morning, all without gaining a pound. 

每个人身边都会有这样一个人——吃的比看起来能吃的多，喝下超过他份额的啤酒，狼吞虎咽下一整块意大利腊肠披萨，在抓一个冰淇淋，第二天早上在吃一个甜甜圈，然后体重一磅都不会增加。

A new study suggests that people's bodies respond to the same food in very different ways.

一项新研究表明，人们的身体对于相同食物的处理因人而异。

"If you have two people who are given the same exact diet, they won't necessarily weigh the same." says Dr. Judith Korner, director at the Weight Control Center at Columbia University Medical Center.

“如果两个人都吃完全相同的食物，那么他们也不会增长完全相同的重量。”哥伦比亚大学医学中心，体重控制中心的主任Judith Korner博士如是说。

1. They've got good genes

他们有好的基因

Not happy with the way your body looks when you stray from your otherwise healthy diet? Blame mom and dad. Dr. Korner says genetics program your "set point," the weight your body strives to maintain. Some people may have a set point at a BMI of 22, while other bodies have a tendency to maintain a BMI of 28 or 30, depending on their genes and hormones."If you try and alter that set point, your body definitely fights against it," Dr. Korner continues. "There have been studies where you take people of any size, thin or obese, and if you underfeed them, there are changes in the body that try to get them back to their original weight. It also works the other way too -- the body will try to burn up that extra food to get them back to the set point."

已经坚持了健康的饮食对自己的体形还是不满意，那就怪你的爸妈吧。Korner博士说，基因决定了你体重的“基准点”，你的身体会尽量保持在这个基准点。有些人的基准点是BMI(体重指数=体重/身高的平方)22，而有些人的IBM则要达到28或者30，这是他们的基因和荷尔蒙决定的。如果你试着认为调整你的“体重指数“，那你的身体会尽可能的反抗。Korner博士继续说道，“研究表明，不管人们来自哪里，体形，胖瘦如何，如果你不满足身体的需求，那么自身的调节系统会努力把你的体重拉到“基准值”，反之，如果你摄入过多的脂肪，那么身体也会帮助消耗，把你的体重保持在“基准值”。

2. Their metabolisms are at roadrunner levels

他们的新陈代谢能力达到公路跑步者水平

The formula for weight gain is pretty simple: consume more calories than you burn, and vice versa. But how many calories you burn daily is much more dependent on your metabolism than hours spent at the gym. In fact, basic functions, like breathing and circulation, account for nearly three-quarters of the calories you burn daily, and your genetics determine this basal metabolic rate."[If your friend] is really having many more calories than you are, then his metabolism is probably faster and his body uses up calories much, much more quickly. That's probably how he was born," says Dr. Korner. " (It's like how) some people are born with blue eyes and some with brown eyes."

增加体重的公式相当的简单：吃的比你消耗的多，反之亦然。你每天消耗多少卡路里比起在健身房锻炼更其实依赖于你自己的新陈代谢。事实上，人体的基本功能，像呼吸、循环等每天就会消耗你四分之三的卡路里，你的基因决定了你基本的新陈代谢的速率。“如果你的朋友比你摄入了更多的卡路里，但是他的新陈代谢的速度比你更快，那么他消耗的卡路里含量就比要多。这是天生的。”Korner 博士说，“就像有些人的眼睛天生是蓝色的，有些人是棕色的原理是一样”

3. They're eating less energy-dense foods

他们少吃高热量的食物

A pound of lettuce may weigh the same as a pound of fried chicken, but they certainly don't have the same effect on the body. That chronically thin friend who's constantly eating might actually be consuming foods that are less caloric than you think, Dr. Korner points out."It can look like someone's eating a lot, maybe they'll have this giant bowl in front of them, but the bowl may contain a salad of beans, chicken, and no dressing," she says. "It looks like they're just chewing and chewing and chewing, but their foods are less energy dense."There are people who say they eat whatever they want without gaining weight -- and they're not lying. While that might conjure up feasts of fried chicken, mac & cheese, and cream puffs in your mind, their palates may prefer less-caloric foods, allowing them to eat a much larger quantity.

一磅的生菜和一磅的炸鸡，但是他们对身体的影响是不同的。看起来爱吃但一直很瘦的朋友，摄入的食物的卡路里不是你想的那么多。Korner博士指出，“他们看起来感觉吃了很多，面前放那么大一个碗吃饭，但是碗里就只有豆类、鸡肉混合的沙拉，都没有加调味汁。”她说，“看起来他们就一直在不停的吃啊吃，但其实食物中的热量很少。”所有当有人说他们很能吃，但就是吃不胖——（这就是他们吃不胖的原因）他们没有撒谎。当你想象着，他们肯定能吃很多炸鸡、巨无霸芝士汉堡、还有奶油泡芙。事实上他们盘子里都是低热量的食物，所以他们能吃很多。

4. They probably don't actually eat that much

他们实际上可能吃得并没有那么多

Reality is not always as it seems. People tend to eat more and indulge in their favorite foods when they're out with friends, calorie counts be damned. Even if you saw your friend consume more chicken nuggets last night than you eat in six months, their regular diet is likely more modest."I think that it's an exaggeration. They may be eating what they want, but probably the number of calories they're consuming is not huge. If they start eating thousands of calories a day, I think that they would gain weight," says Dr. Korner.The opposite is true too, says Dr. Korner, who has seen patients that claim they've cut calories but still haven't seen the scale budge. Their perceptions of their diets are probably off."If you look at their food diary, you'll see a granola bar, and the patient thought that it was healthy but didn't realize the number of calories in this supposedly healthy granola bar was pretty significant. It's thermodynamically impossible to take in less [than you burn] and not lose weight." The best diet is always the one that works for you, not someone else's plan.

事实并不是看起来的那样。当人们和朋友们出去的时候，他们往往会吃的更多，特别是他们喜欢的食物，卡路里自然也会飙升。即使你看见你朋友一次性吃的鸡块比你过去半年吃的还要多，（但你不知道的是）他们平时饮食可能是极其严格。“我想可能有点夸张。他们可能就是吃他们想吃的东西，但是摄入的卡路里没有那么多。如果他们摄入每天数千卡路里，那他们的体重可能会增加，如果情况相反，那体重就会减少”Korner博士如是说，他曾经碰到过病人抱怨，他已经在节食了，但是体重并没有减少。他们觉得自己的节食不起效果了。“但是如果你看他们的饮食日记，你会看见上面写了麦棒，而且病人认为那是健康食品，但是它不知道里面含了多少卡路里，而这点才是最重要的。”最好的饮食是适合你的，而不是（盲目照搬）其他人的饮食计划。