Your body requires a continuous supply of energy just to stay alive - to keep the heart pumping, breathe, and maintain body temperature. Your brain requires a huge amount of energy; its cells burn about 120 grams (g) - about half a cup of glucose a day, accounting for about 15 percent of total oxygen consumption. Maintaining（维护） brain cells and other life-sustaining（持续地） activities uses as much as 75 percent of the energy a person takes in as food during a typical day.
你的身体一天需要持续地消耗能量以维持生理活动——让心脏跳动，呼吸，以及保持体温。你的大脑需要消耗大量的能量；脑细胞一天燃烧120克的能量——约等于半杯葡萄糖，其中有百分之15是氧气。维护脑细胞和其他持续的生理活动需要消耗人们每天进食的75%的能量。

Above and beyond the energy you need for body maintenance, cellular(细胞的) respiration（呼吸） provides energy for voluntary（自愿的） activities. For example, consider the amount of energy it takes to perform some of these activities. The energy units are kilocalories(kcal), the quantity of heat required to raise the temperature of 1 kilogram(kg) of water by 1° Celsius. (The "Calories" listed on food packages are actually kilocalories, usually signified by a capital C.) The values shown do not include the energy the body consumes for its basic life-sustaining activities. Even sleeping or lying quietly requires energy for metabolism（新陈代谢）.
除了用能量维持你的生理活动，细胞的呼吸给自发的生理活动提供能量。例如，考虑执行这些活动所需的能量。能量单位是千卡（kcal），使一千克（kg）水的温度升高一摄氏度所需要的热量（食物中含有的“卡路里”通常来说是千卡，以大写字母C作为符号）。所显示的数值不包括人体为维持生命的基本活动所消耗的能量。甚至睡觉或者躺着都需要消耗能量以维持新陈代谢。

Energy consumed by Various Activities
各种活动消耗的能量

Not including the kcal needed for body maintenance
以上数据不包含维持生命基本活动所需要的卡路里

Canada's Food Guide estimates（估计） that the average adult(ages nineteen to thirty) needed to take in food that provides about 2,700 kcal of energy per day for men and about 2100 kcal per day for woman. This includes the energy expended in both maintenance and voluntary activity.
“加拿大食物指导”估计一名普通的成年男性（19岁-30岁）每天需要2700千卡的能量，一名女性需要2100千卡的能量。这包含了用于维持生理活动的能量。

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over-nourishment（营养过剩）, consuming（消耗） more food energy than the body needs for normal metabolism, causes obesity, the excessive（过多的） accumulation（聚集） of fat. The World Health Organization new recognizes（认出） obesity is a major global health problem. The increased availability of fattening（使人发胖的） foods and large portions（部分）, combined（组合的） with more sedentary(久坐的) lifestyles, puts excess（额外的） weight on bodies. A standard method of determining healthy weight is body mass index(BMI), a ratio of weight to height... A BMI of 25-30 is considered overweight, and above 30 is obese（肥胖）. In Canada, the percentage of obese(very overweight) people has been increasing in recent years, reaching 17.5 percent in 2010. A further 3.1 percent of Canadians are overweight. Weight problems often begin at a young age: above 26 percent of Canadian children and adolescents are either overweight or obese.
营养过剩，摄入比人体新陈代谢所需要的更多的能量，导致肥胖，即脂肪过多聚集。世界卫生组织最新显示出肥胖是全球性的主要健康问题之一。食物增长点能让人发胖的能力结合大部分人久坐的生活方式，让人们增重不少……一个测量健康体重的标准是身体质量指数（BMI），一个身高和体重的比率……BMI指数为25-30意味着超重，超过30意味着肥胖。在加拿大，人们肥胖（特别超重）的百分比逐年上升。在2010年时达到了17.5%。另外有3.1%的加拿大人是超重的。体重问题通常在较小的年龄就开始了：超过26%的加拿大儿童和青少年超重或者肥胖。

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Some of our current（现在的） struggles with obesity may be a consequence of our evolutionary history. Most of us crave（渴望） foods that are fatty: fries, chips, Burgers, cheese, and ice cream. Though fat hoarding（储藏） can be a health liability（责任） today, it may actually have been advantageous in our evolutionary past. Only in the past few centuries have large numbers of people had access to a reliable（可靠的） supply of high calorie food. Our ancestors on the African savannah（大草原） were hunter-gatherers（采集者） who probably survived mainly（主要地） on seeds and other plant products, a diet only occasionally（偶尔） supplemented（补充） by hunting game or scavenging（清除） meat from animals killed by other predators（捕食者）. In such a feast（享受） and famine（饥荒） existence, natural selection may have favored those individual（个人的）s with the physiology（生理学） that induced them to gorge（吞下） on rich（油腻的）, fatty foods on those rare（稀有的） occasions（时机） when such treats were available. Individuals with genes（基因） promoting the storage（存储） of fat during feasts may have been more likely than their thinner peers to survive famines.
我们现在的一些和肥胖之间的斗争可能是由我们的进化史引起的。大部分的我们渴望的食物是高脂肪的：薯条、薯片、汉堡、芝士和冰激凌。尽管储藏脂肪是我们的责任，但这实际上是我们过去我们进化时对我们有利的。只有过去几个世纪人们才获得了稳定的高卡路里食物的供给。我们非洲大草原上的祖先主要通过采集种子和其他植物获得食物，偶尔靠收集起他捕食者杀死的动物来获取食物。人们在吃饱和饥饿之中生存着，而在少有的可以吃到油腻的和富有脂肪的食物时候吃掉这些食物能增加我们活下来的机会。个人基因保证了在这些时候存储更多脂肪的人，在饥荒的时候会有更大的概率活下去。

So perhaps our modern taste for fats and sugars reflect the selective advantage it conveyed（传达） in our evolutionary history. Although we know it is unhealthy, many of us find it difficult to overcome the ancient survival behavior of stockpiling（储藏） for the next famine.
所以或许我们现在吃脂肪和糖的味道反映了进化史传达给我们的在自然选择之中的优势因素。尽管我们知道这是不健康的，大多数人还是很难避免由古老的应对饥荒所形成的生存方式引起的超重问题。