为什么演讲稿范文3篇

简介：在美国，80%的女孩在她们10岁的时候便开始节食。神经学家sandra aamodt结合自己的亲身经历，讲述大脑是如何控制我们的身体的。节食减肥为何没效果?来听听她的说法吧!

three and a half years ago, i made one of the best decisions of my life. as my new year's resolution, i gave up dieting, stopped worrying about my weight, and learned to eat mindfully. now i eat whenever i'm hungry, and i've lost 10 pounds.

this was me at age 13, when i started my first diet. i look at that picture now, and i think, you did not need a diet, you needed a fashion consult. (laughter) but i thought i needed to lose weight, and when i gained it back, of course i blamed myself. and for the next three decades, i was on and off various diets. no matter what i tried, the weight i'd lost always came back. i'm sure many of you know the feeling.

as a neuroscientist, i wondered, why is this so hard? obviously, how much you weigh depends on how much you eat and how much energy you burn. what most people don't realize is that hunger and energy use are controlled by the brain, mostly without your awareness. your brain does a lot of its work behind the scenes, and that is a good thing, because your conscious mind -- how do we put this politely? -- it's easily distracted. it's good that you don't have to remember to breathe when you get caught up in a movie. you don't forget how to walk because you're thinking about what to have for dinner.

your brain also has its own sense of what you should weigh, no matter what you consciously believe. this is called your set point, but that's a misleading term, because it's actually a range of about 10 or 15 pounds. you can use lifestyle choices to move your weight up and down within that range, but it's much, much harder to stay outside of it. the hypothalamus, the part of the brain that regulates body weight, there are more than a dozen chemical signals in the brain that tell your body to gain weight, more than another dozen that tell your body to lose it, and the system works like a thermostat, responding to signals from the body by adjusting hunger, activity and metabolism, to keep your weight stable as conditions change. that's what a thermostat does, right? it keeps the temperature in your house the same as the weather changes outside. now you can try to change the temperature in your house by opening a window in the winter, but that's not going to change the setting on the thermostat, which will respond by kicking on the furnace to warm the place back up.

your brain works exactly the same way, responding to weight loss by using powerful tools to push your body back to what it considers normal. if you lose a lot of weight, your brain reacts as if you were starving, and whether you started out fat or thin, your brain's response is exactly the same. we would love to think that your brain could tell whether you need to lose weight or not, but it can't. if you do lose a lot of weight, you become hungry, and your muscles burn less energy. dr. rudy leibel of columbia university has found that people who have lost 10 percent of their body weight burn 250 to 400 calories less because their metabolism is suppressed. that's a lot of food. this means that a successful dieter must eat this much less forever than someone of the same weight who has always been thin.

from an evolutionary perspective, your body's resistance to weight loss makes sense. when food was scarce, our ancestors' survival depended on conserving energy, and regaining the weight when food was available would have protected them against the next shortage. over the course of human history, starvation has been a much bigger problem than overeating. this may explain a very sad fact: set points can go up, but they rarely go down. now, if your mother ever mentioned that life is not fair, this is the kind of thing she was talking about. (laughter) successful dieting doesn't lower your set point. even after you've kept the weight off for as long as seven years, your brain keeps trying to make you gain it back. if that weight loss had been due to a long famine, that would be a sensible response. in our modern world of drive-thru burgers, it's not working out so well for many of us. that difference between our ancestral past and our abundant present is the reason that dr. yoni freedhoff of the university of ottawa would like to take some of his patients back to a time when food was less available, and it's also the reason that changing the food environment is really going to be the most effective solution to obesity.

sadly, a temporary weight gain can become permanent. if you stay at a high weight for too long, probably a matter of years for most of us, your brain may decide that that's the new normal.

psychologists classify eaters into two groups, those who rely on their hunger and those who try to control their eating through willpower, like most dieters. let's call them intuitive eaters and controlled eaters. the interesting thing is that intuitive eaters are less likely to be overweight, and they spend less time thinking about food. controlled eaters are more vulnerable to overeating in response to advertising, super-sizing, and the all-you-can-eat buffet. and a small indulgence, like eating one scoop of ice cream, is more likely to lead to a food binge in controlled eaters. children are especially vulnerable to this cycle of dieting and then binging.

several long-term studies have shown that girls who diet in their early teenage years are three times more likely to become overweight five years later, even if they started at a normal weight, and all of these studies found that the same factors that predicted weight gain also predicted the development of eating disorders. the other factor, by the way, those of you who are parents, was being teased by family members about their weight. so don't do that. (laughter)

i left almost all my graphs at home, but i couldn't resist throwing in just this one, because i'm a geek, and that's how i roll. (laughter) this is a study that looked at the risk of death over a 14-year period based on four healthy habits: eating enough fruits and vegetables, exercise three times a week, not smoking, and drinking in moderation. let's start by looking at the normal weight people in the study. the height of the bars is the risk of death, and those zero, one, two, three, four numbers on the horizontal axis are the number of those healthy habits that a given person had. and as you'd expect, the healthier the lifestyle, the less likely people were to die during the study. now let's look at what happens in overweight people.

the ones that had no healthy habits had a higher risk of death. adding just one healthy habit pulls overweight people back into the normal range. for obese people with no healthy habits, the risk is very high, seven times higher than the healthiest groups in the study. but a healthy lifestyle helps obese people too. in fact, if you look only at the group with all four healthy habits, you can see that weight makes very little difference. you can take control of your health by taking control of your lifestyle, even if you can't lose weight and keep it off.

diets don't have very much reliability. five years after a diet, most people have regained the weight. forty percent of them have gained even more. if you think about this, the typical outcome of dieting is that you're more likely to gain weight in the long run than to lose it.

if i've convinced you that dieting might be a problem, the next question is, what do you do about it? and my answer, in a word, is mindfulness. i'm not saying you need to learn to meditate or take up yoga. i'm talking about mindful eating: learning to understand your body's signals so that you eat when you're hungry and stop when you're full, because a lot of weight gain boils down to eating when you're not hungry. how do you do it? give yourself permission to eat as much as you want, and then work on figuring out what makes your body feel good. sit down to regular meals without distractions. think about how your body feels when you start to eat and when you stop, and let your hunger decide when you should be done. it took about a year for me to learn this, but it's really been worth it. i am so much more relaxed around food than i have ever been in my life. i often don't think about it. i forget we have chocolate in the house. it's like aliens have taken over my brain. it's just completely different. i should say that this approach to eating probably won't make you lose weight unless you often eat when you're not hungry, but doctors don't know of any approach that makes significant weight loss in a lot of people, and that is why a lot of people are now focusing on preventing weight gain instead of promoting weight loss. let's face it: if diets worked, we'd all be thin already. (laughter)

why do we keep doing the same thing and expecting different results? diets may seem harmless, but they actually do a lot of collateral damage. at worst, they ruin lives: weight obsession leads to eating disorders, especially in young kids. in the u.s., we have 80 percent of 10-year-old girls say they've been on a diet. our daughters have learned to measure their worth by the wrong scale. even at its best, dieting is a waste of time and energy. it takes willpower which you could be using to help your kids with their homework or to finish that important work project, and because willpower is limited, any strategy that relies on its consistent application is pretty much guaranteed to eventually fail you when your attention moves on to something else.

let me leave you with one last thought. what if we told all those dieting girls that it's okay to eat when they're hungry? what if we taught them to work with their appetite instead of fearing it? i think most of them would be happier and healthier, and as adults, many of them would probably be thinner. i wish someone had told me that back when i was 13.

thanks.

(applause)

TED英语演讲稿：为什么X代表未知？ 为什么演讲稿范文（2）

i have the answer to a question that we've all asked. the question is, why is it that the letter x represents the unknown? now i know we learned that in math class, but now it's everywhere in the culture -- the x prize, the x-files, project x, tedx. where'd that come from?

about six years ago i decided that i would learn arabic, which turns out to be a supremely logical language. to write a word or a phrase or a sentence in arabic is like crafting an equation, because every part is extremely precise and carries a lot of information. that's one of the reasons so much of what we've come to think of as western science and mathematics and engineering was really worked out in the first few centuries of the common era by the persians and the arabs and the turks.

this includes the little system in arabic called al-jebra. and al-jebr roughly translates to "the system for reconciling disparate parts." al-jebr finally came into english as algebra. one example among many.

the arabic texts containing this mathematical wisdom finally made their way to europe -- which is to say spain -- in the 11th and 12th centuries. and when they arrived there was tremendous interest in translating this wisdom into a european language.

but there were problems. one problem is there are some sounds in arabic that just don't make it through a european voice box without lots of practice. trust me on that one. also, those very sounds tend not to be represented by the characters that are available in european languages.

here's one of the culprits. this is the letter sheen, and it makes the sound we think of as sh -- "sh." it's also the very first letter of the word shalan, which means "something" just like the the english word "something" -- some undefined, unknown thing.

now in arabic, we can make this definite by adding the definite article "al." so this is al-shalan -- the unknown thing. and this is a word that appears throughout early mathematics, such as this 10th century derivation of proofs.

the problem for the medieval spanish scholars who were tasked with translating this material is that the letter sheen and the word shalan can't be rendered into spanish because spanish doesn't have that sh, that "sh" sound. so by convention, they created a rule in which they borrowed the ck sound, "ck" sound, from the classical greek in the form of the letter kai.

later when this material was translated into a common european language, which is to say latin, they simply replaced the greek kai with the latin x. and once that happened, once this material was in latin, it formed the basis for mathematics textbooks for almost 600 years.

but now we have the answer to our question. why is it that x is the unknown? x is the unknown because you can't say "sh" in spanish. (laughter) and i thought that was worth sharing.

(applause)

中国梦演讲稿——我为什么要学法律 为什么演讲稿范文（3）

尊敬的各位老师，同学们，大家好！

我是法学院大四学生李明，我演讲的题目是《我为什么要学法律》

很多人听到这个题目，一定以为我太把这次演讲比赛当做儿戏了。一个简单的专业选择的问题，与我们今天的主题“中国梦”能有多大的关联呢？其实在初入燕园之时，我也只曾在大众媒体和长辈的口耳相传中听得法律职业者的种种评价，也只曾知道“宪法是我国根本大法”之类的政治课本知识，也只曾在路过国徽高悬的庄严肃穆的法院门口时好奇的回望。而今，我即将从北大法学院毕业，成为一名光荣的北大法律人，我所应当肩负的责任是什么，我可能实现的人生价值在历史的坐标下又是什么？

我想，这个简单的问题，不仅仅是我四年燕园求学中努力求索的精神真谛，而且将是指导我未来发展的永恒旗帜。法律人，应该有着怎样的中国梦，这需要我们用整个人生去回答。

法律人的中国梦，是维护公民合法利益的权利之梦。法治，绝不应当仅仅是宏大的制度构建，而也应当构筑起公民权利的堡垒，让苦干多年农民工兄弟早日拿到血汗钱，让征地拆迁中的血案不再上演，让猖獗一时的刑讯逼供无处藏身。法学家耶林告诉我们，要“为权利而斗争”，因为当每个人都在强权面前退却的时候，整个共同体的利益将不得不被放弃。法律人站在公民权利与强权暴力交锋的战场，捍卫每个人的权利，捍卫每个人的中国梦。

法律人的中国梦，是追求社会公平的正义之梦。坚韧的法律人，让苍南县政府做到了被告席上，与浙江普通农民包郑照对簿公堂。执着的法律人，让佘祥林、赵作海获得了他们应得的国家赔偿，使冤案昭雪，真相大白。让比太阳还要光辉的公平正义洒满人间，是法律人永恒的信条。

法律人的中国梦，是让中华民族真正实现民主与文明的复兴之梦。法律人梦想着让每个人都有行使民主权利的机会，共享国家发展带来的成果；法律人希望能够用制度构建约束权力的牢笼，让腐木与蛀虫无处藏身；法律人希望能够走出一条具有中国特色的民主、法治之路，让中华民族以更加文明的姿态屹立于世界东方，让中国梦成为世界所景仰的精神价值。

也许还有人仅仅是为了在诉讼和争议中获得利益，利用法律规避责任而无视事实真相的存在；也许还有人仅仅是为了粉饰太平，偏袒强者欺压弱者，息事宁人而将公平正义束之高阁；也许还有人仅仅是为了维护旧秩序的稳定，坐拥恶法，助纣为虐。但中国梦的号角已经吹响，驶向中华民族伟大复兴的巨轮已经起航，一切的不完美，都等待着我们去改变。我们怎样，中国便怎样。我们是什么，中国便是什么。我们有光明，中国便不再黑暗。

在古希腊神话中，代表正义的女神是这样的形象：她双眼紧蒙，代表不受干扰和高贵的逻辑理性；她手握天平，代表绝对公平绝不偏袒；她手握利剑，代表践行正义绝不姑息。法律人，正是怀着崇高的理性精神，践行对社会公平正义的追求，在推进人类文明的道路上披荆斩棘，为公民权利而战，为公平正义而战，为社会进步和民族复兴而战！

我为什么要学法律，我想，法律人的中国梦，已经告诉我答案。

马岩松励志演讲稿：我们为什么要谈未来 2018为什么演讲稿（4）

我叫马岩松，我是个建筑师，我今天讲的是，我们为什么要谈未来，我曾经被一个很重要的批评家问过一个问题，他说，未来将会是什么，当时我就想怎么回答这个问题。最后我给他一个答案呢，就是未来就是过去。

大概是XX年吧，这时候我已经在北京工作，我们做了一个竞赛，这个竞赛在中国的一个大城市，竞赛要求建一个四百米的一个楼，然后政府的人说，虽然我们写的是400米，但是呢，你们可以来表达你们认为的一个高度，他这个话呢大家都明白了，就是他想要一个更高的，他要一个更高的楼，来表达这个城市的一个信心。结果呢，所有的建筑师都设计了一个高于400米的，高于400米，500米，600米，当时还没有迪拜这个800米的事儿，然后我当时就想，那我就来一个800米的吧。然后我跟政府汇报的第一句就是你想要一个世界第一高的楼吗?我们这是一个800米的，但是这个800米的楼呢，其实只有400米，但是它是两截，400米上去了然后又转下来，一共800米。等于是楼顶又回到了地面，然后我们就输了，不但输了，而且十几年过去了，我们现在还没拿到设计费，就是他们生气了。生气呢，我觉得可能是这个，对这个玩笑有点接受不了，很多地方都想建超越盘，建一个更高的楼，用更高的楼代表他们的野心。可是现在时间又不一样了，现在我们已经开始上火星了，技术已经很发达，建一个高层建筑其实并不难，挑战不了技术，只是挑战钱，所以高层建筑就慢慢变成了权力和资本的一个纪念碑，所以这个时代呢，我觉得已经不是再去赞美权力和资本的时代了。都想建大楼，都想用高楼来代表他们的信心，来代表一个城市创造力的时候，我就觉得非常愚蠢，所以把这个玩笑当成是一种对现实的批判。每一个对现实的批判，我都认为指向一个更好的未来。但这个未来呢，就永远不发生。

每一次我们的提案都是输，直到我们做了一个竞赛，是在国外，我们赢了一个高层建筑的竞赛，这个项目在加拿大，在北美，大家都直到我们今天中国的城市都是在山寨北美，北美是高层建筑，是这种现代城市的故乡，我们在北美能设计一个房子，我就想能不能去，不去跟其他的楼一样，去抢这样的高度，力量，我设计一个自然的高层建筑，因为很多人说这个曲线像一个女人的曲线，然后加拿大管这个楼叫“梦露大厦”，然后我们就有一天收到一封信，就说你们入围了，这时候我觉得非常地习惯，因为入围之前，我们经常入围，但是我们确定他们不会选我们。第一因为我们是中国的，中国的建筑师，在北美设计一个房子，以前从来没听说过。第二，我觉得他们让我们入围，可能是看上我们的这个图，跟他们以前建造的这些高楼，都不一样。但是当建造的时候，可能所有人都该说，怎么建呀?结构是什么样?会不会花很多钱?但我还是去了，我一点也不紧张。我觉得，我觉得我就是抱着一种不会被选上这么一个心态去。不会被选上的心态对我来说是非常重要的。如果被选上了，我会觉得心里不舒服，我会觉得他们看懂我了，我会觉得我可能谄媚他们了，为什么我的批判，我的玩笑，我对他们的刺激，还能被他们高兴地接受。所以那样的结果，可能对我来说更残酷的，我基本上已经习惯了不被接受的，不能建的这个状态。又过了两个月，他们最后决定要建我们这个楼了，我觉得他们疯了，但我又说不出来为什么他们疯了，我只知道大部分人不会做这样的决定，我也为他们捏把汗，因为那时候我还基本上没怎么工作过，我也没建过什么房子。我想如果你们谁家想盖一房子，找一建筑师，至少这个人以前是盖过房子的吧，更何况是建一个城市地标。所以这件事突然让我有了信心，我觉得我好像也能建房子了。

但我又有一点害怕，我觉得我批判，一个指向未来的建筑，怎么说盖就盖起来了，这个未来是不是，本来就不是未来啊。所以当这个高层建筑在北美开工的时候，我就在想，我真正的未来是什么?山水城市，我认为是源于对未来的渴望，是要解决现实的问题，是想建造一个有情感的、有自然的、有生活的这样的城市。我们现在呢，又是在这么一个阶段，就是生活在自己的臆想里面，你要问我具体的问题，说这个到底是什么，我也不知道。但是我喜欢这种状态，让我越来越接近未来，我希望能跟未来有一个对话，谢谢!