首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Calories For years now, calories have been all the rage-people are counting them and cutting them, and you’d be hard-pressed
Calories For years now, calories have been all the rage-people are counting them and cutting them, and you’d be hard-pressed
admin
2010-04-30
27
问题
Calories
For years now, calories have been all the rage-people are counting them and cutting them, and you’d be hard-pressed to find something at the supermarket that does not list its calories per serving somewhere on the package. But have you ever wondered what exactly a calorie is?
What is a Calorie
A calorie is a unit of energy. We tend to associate calories with food, but they apply to anything containing energy. For example, a gallon (about 4 liters) of gasoline contains about 31,000,000 calories.
Specifically, a calorie is the amount of energy, or heat, it takes to raise the temperature of 1 gram of water 1 degree Celsius (1.8 degrees Fahrenheit). One calorie is equal to 4. 184 joules, a common unit of energy used in the physical sciences. Most of us think of calories in relation to food, as in "This can of soda has 200 calories." It turns out that the calories on a food package are actually kilocalories (1,000 calories = 1 kilocalorie). The word is sometimes capitalized to show the difference, but usually not. A food calorie contains 4,184 joules. A can of soda containing 200 food calories contains 200,000 regular calories, or 200 kilocalories. A gallon of gasoline contains 31,000 kilocalories.
The same applies to exercise — when a fitness chart says you burn about 100 calories for every mile you jog, it means 100 kilocalories. For the duration of this article, when we say "calorie," we mean "kilocalorie."
What Calories Do
Human beings need energy to survive — to breathe, move, pump blood — and they acquire this energy from food.
The number of calories in a food is a measure of how much potential energy that food possesses. A gram of carbohydrates(碳水化合物) has 4 calories, a gram of protein has 4 calories, and a gram of fat has 9 calories. Foods are a compilation (集合) of these three building blocks. So if you know how many carbohydrates, fats and proteins are in any given food, you know how many calories, or how much energy, that food contains.
If we look at the nutritional label on the back of a packet of maple-and-brown-sugar oatmeal, we find that it has 160 calories. This means that if we were to pour this oatmeal into a dish, set the oatmeal on fire and get it to burn completely (which is actually pretty tricky), the reaction would produce 160 kilocalories (remember: food calories are kilocalories) — enough energy to raise the temperature of 160 kilograms of water 1 degree Celsius. If we look closer at the nutritional label, we see that our oatmeal has 2 grams of fat, 4 grams of protein and 32 grams of carbohydrates, producing a total of 162 calories (apparently, food manufacturers like to round down). Of these 162 calories, 18 come from fat (9 cal × 2g), 16 come from protein(4 cal × 4g) and 128 come from carbohydrates (4 cal × 32g).
Your Calorie Needs
Just how many calories do our cells need to function well? The number is different for every person. You may notice on the nutritional labels of the foods you buy that the "percent daily values" are based on a 2,000 calorie diet — 2,000 calories is a rough average of what a person needs to eat in a day, but your body might need more or less than 2,000 calories. Height, weight, gender, age and activity level all affect your caloric needs. There are three main factors involved in calculating how many calories your body needs per day:
• Basal metabolic rate (基本新陈代谢率)
• Physical activity
• Thermic (热的) effect of food
Your basal metabolic rate (BMR) is the amount of energy your body needs to function at rest. This accounts for about 60 to 70 percent of calories burned in a day and includes the energy required to keep the heart beating, the lungs breathing, the kidneys functioning and the body temperature stabilized. In general, men have a higher BMR than women.
The second factor in the equation, physical activity, consumes the next highest number of calories. Physical activity includes everything from making your bed to jogging. Walking, lifting, bending, and just generally moving around burns calories, but the number of calories you burn in any given activity depends on your body weight.
The thermic effect of food is the final addition to the number of calories your body burns. This is the amount of energy your body uses to digest the food you eat — it takes energy to break food down to its basic elements in order to be used by the body. To calculate the number of calories you expend in this’ process, multiply the total number of calories you eat in a day by 0.10, or 10 percent.
Calories, Fat and Exercise
So what happens if you take in more or fewer calories than your body burns? You either gain or lose fat, respectively. An accumulation of 3,500 extra calories is stored by your body as 1 pound of fat — fat is the body’s way of saving energy for a rainy day (以备不时之需). If, on the other hand, you burn 3,500 more calories than you eat, whether by exercising more or eating less, your body converts 1 pound of its stored fat into energy to make up for the deficit.
One thing about exercise is that it raises your metabolic rate not only while you’re buffing and puffing(喘气) on the treadmill. Your metabolism takes a while to return to its normal pace. It continues to function at a higher level; your body burns an increased number of calories for about two hours after you’ve stopped exercising.
Lots of people wonder if it matters where their calories come from. At is most basic, it we eat exactly the number of calories that we burn and if we’re only talking about weight, the answer is no — a calorie is a calorie. A protein calorie is no different from a fat calorie — they are simply units of energy. As long as you burn what you eat, you will maintain your weight; and as long as you burn more than you eat, you’ll lose weight.
But if we’re talking nutrition, it definitely matters where those calories originate. Carbohydrates and proteins are healthier sources of calories than fats. Although our bodies do need a certain amount of fat to function properly — an adequate supply of fat allows your body to absorb the vitamins you ingest — an excess of fat can have serious health consequences. The U. S. Food and Drug Administration recommends that a maximum of 30 percent of our daily calories come from fat. So, if you eat 2,000 calories a day, that’s a maximum of 600 calories from fat, or 67 grams of fat, per day. However, many doctors and nutritionists now set the maximum number of fat calories at 25 percent of our daily caloric intake. That’s 56 grams of fat per day for a 2,000 calorie diet.
Your basal metabolic rate(BMR) is the amount of energy your body needs to ______while you are sleep.
选项
答案
function
解析
转载请注明原文地址:https://kaotiyun.com/show/VROK777K
0
大学英语六级
相关试题推荐
Nodirectrelationshiphasbeenprovenbetweenhighcholesterollevelsandheartattacks.Oneoftheeducationalactivitiesin
Fromthefirstsentencewelearnthatresearchers______.Itisimpliedinthepassagethatthebabiesattheday-carecenter_
Collegestudentsshouldbewell______(意识到沉溺于电脑游戏的危险性).
EducationisanenormousandexpensivepartofAmericanlife.Itssizeismatchedbyitsvariety.DifferencesinAmericansc
A、Artislosingitsaudienceinmodemsociety.B、Artshouldbeencouragedinhospitals.C、Worksofartshouldhaveplacesforex
ProfessorBhattandRobMeakinhavedevelopedamethodto______.HowdoesProfessorBhattfeelaboutmanyleadersincompanies
AstheEnglishlanguagehaschangedatafastspeedinthiscentury,sohastheuseoftheEnglishlanguage.AftertheBriti
Kunzgaveupsoftwareengineeringmainlybecauseheearnedlessthanthoseinlaworbusinessfielddid.Cuttingbudgetforsci
CaloriesForyearsnow,calorieshavebeenalltherage-peoplearecountingthemandcuttingthem,andyou’dbehard-pressed
A、Countingsheep.B、Taking:sleepingpills.C、Drinkingcoffee.D、Drinkingmilk.A细节题。问的是对话中所提到的帮助睡眠的老方法,尽管答案都用来帮助睡眠,但是文章中只提到了一种
随机试题
角度铣刀的刀尖部分()较弱,容易折断。
计算机的算法具有可行性、有穷性、________和输入/输出。
A、Shethinksthattoomanyclonedmenandwomenwillbeneeded.B、Shethinksthatweneedmoregreatpeople.C、Shethinksthath
上巨虚的主治有
华新公司与洪泽公司签订了一份买卖钢材合同。合同约定华新公司先交货。交货前夕,华新公司派人调查洪泽公司的偿债能力,有确切材料证明洪泽公司负债累累,根本不能按时支付货款,华新公司遂决定暂时不向洪泽公司交货。华新公司的行为是()。
贷款公司是专门为县域农民、农业和农村经济发展提供贷款服务的非银行金融机构。()
分子生物学的研究表明()。
在分配方案中,包括()重要信息。
1926年7月,北伐战争开始,其目标是()
Hebehavesinastrangemanner,andnobodycan______this.
最新回复
(
0
)