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（維護） brain cells and other life-sustaining（持續地） activities uses as much as 75 percent of the energy a person takes in as food during a typical day.
你的身體一天需要持續地消耗能量以維持生理活動——讓心臟跳動，呼吸，以及保持體溫。你的大腦需要消耗大量的能量；腦細胞一天燃燒120克的能量——約等于半杯葡萄糖，其中有百分之15是氧氣。維護腦細胞和其他持續的生理活動需要消耗人們每天進食的75%的能量。

Above and beyond the energy you need for body maintenance, cellular(細胞的) 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（新陳代謝）.
除了用能量維持你的生理活動，細胞的呼吸給自發的生理活動提供能量。例如，考慮執行這些活動所需的能量。能量單位是千卡（kcal），使一千克（kg）水的溫度升高一攝氏度所需要的熱量（食物中含有的“卡路里”通常來說是千卡，以大寫字母C作為符號）。所顯示的數值不包括人體為維持生命的基本活動所消耗的能量。甚至睡覺或者躺著都需要消耗能量以維持新陳代謝。

Energy consumed by Various Activities
各種活動消耗的能量

Not including the kcal needed for body maintenance
以上數據不包含維持生命基本活動所需要的卡路里

Canada's Food Guide estimates（估計） 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.
“加拿大食物指導”估計一名普通的成年男性（19歲-30歲）每天需要2700千卡的能量，一名女性需要2100千卡的能量。這包含了用于維持生理活動的能量。

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over-nourishment（營養過剩）, consuming（消耗） more food energy than the body needs for normal metabolism, causes obesity, the excessive（過多的） accumulation（聚集） of fat. The World Health Organization new recognizes（認出） obesity is a major global health problem. The increased availability of fattening（使人發胖的） foods and large portions（部分）, combined（組合的） with more sedentary(久坐的) lifestyles, puts excess（額外的） 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.
營養過剩，攝入比人體新陳代謝所需要的更多的能量，導致肥胖，即脂肪過多聚集。世界衛生組織最新顯示出肥胖是全球性的主要健康問題之一。食物增長點能讓人發胖的能力結合大部分人久坐的生活方式，讓人們增重不少……一個測量健康體重的標準是身體質量指數（BMI），一個身高和體重的比率……BMI指數為25-30意味著超重，超過30意味著肥胖。在加拿大，人們肥胖（特別超重）的百分比逐年上升。在2010年時達到了17.5%。另外有3.1%的加拿大人是超重的。體重問題通常在較小的年齡就開始了：超過26%的加拿大兒童和青少年超重或者肥胖。

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Some of our current（現在的） 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（儲藏） can be a health liability（責任） 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（偶爾） supplemented（補充） 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（饑荒） existence, natural selection may have favored those individual（個人的）s with the physiology（生理學） that induced them to gorge（吞下） on rich（油膩的）, fatty foods on those rare（稀有的） occasions（時機） when such treats were available. Individuals with genes（基因） promoting the storage（存儲） of fat during feasts may have been more likely than their thinner peers to survive famines.
我們現在的一些和肥胖之間的斗爭可能是由我們的進化史引起的。大部分的我們渴望的食物是高脂肪的：薯條、薯片、漢堡、芝士和冰激凌。盡管儲藏脂肪是我們的責任，但這實際上是我們過去我們進化時對我們有利的。只有過去幾個世紀人們才獲得了穩定的高卡路里食物的供給。我們非洲大草原上的祖先主要通過采集種子和其他植物獲得食物，偶爾靠收集起他捕食者殺死的動物來獲取食物。人們在吃飽和饑餓之中生存著，而在少有的可以吃到油膩的和富有脂肪的食物時候吃掉這些食物能增加我們活下來的機會。個人基因保證了在這些時候存儲更多脂肪的人，在饑荒的時候會有更大的概率活下去。

So perhaps our modern taste for fats and sugars reflect the selective advantage it conveyed（傳達） in our evolutionary history. Although we know it is unhealthy, many of us find it difficult to overcome the ancient survival behavior of stockpiling（儲藏） for the next famine.
所以或許我們現在吃脂肪和糖的味道反映了進化史傳達給我們的在自然選擇之中的優勢因素。盡管我們知道這是不健康的，大多數人還是很難避免由古老的應對饑荒所形成的生存方式引起的超重問題。