一天喝八杯水到底是哪个损人的主意？哈佛大学带我们追寻历史！

一直对每天喝多少水有疑问，尤其是那个被大家传诵的一日八杯的神话。今天有点时间搜寻了这个说法的出处和历史，让我们还原历史的真相，让我们更加了解无知的无畏和所谓专家们建议的无知和可怕。

先告诉大家人家正统西医的结论：喝八杯水是以讹传讹

我简单介绍一下，有耐心您可以自己看。

喝八杯水的说法传自哪里：
遥远的1940年，美国国家学术科学发表了对于一个典型的每天摄入2000大卡热量的食谱来说，需要超过8杯的水来燃烧这些食物。而且这个文章也解释了这些水分是包含从食物中的水分，也就是把你吃的食物内的水分和喝的水算在一起，是8杯（cup)。

大家要注意这里说的杯是cup,这个cup在欧美是一个量具，也就是大家现在米煲或者电饭煲里面带的那个杯子的大小。不知道英美的那个损人把这个cup给变了，居然说成是glass的杯子了，这就是把原来的学术的cup，变成8玻璃杯了。

而今天我们所谓的营养专家们更是以讹传讹，绘声绘色的告诉我们要每天喝8玻璃杯水了，至于一杯是多少，我们国人更是八仙过海各显神通了，看办公室里面大家的杯子呵呵，个个是超级巨无霸，这要8杯水下来，完全是可以洗淋浴用了。

要知道，过多的饮水，是造成肝肾的负担，严重影响身体的健康。

真正的喝水原则应该是渴了就喝，每次少喝，再渴再喝。即可。


附录是英文原件，来自哈佛健康杂志的原文。

How    much watershould you drink?

We’ve heard it for decades:      Drink atleast 8 cups of water a day. Not only can three out offour      adults recitethis bit of health wisdom, but many even feel guiltyif      they don’tmeet the standard. However, this advice may bebased      on amisunderstanding. Some trace it to the 1940s, when theNational      Academy ofSciences published a recommended daily allowance of 1milliliter      of fluid foreach calorie burned—a little over 8 cups for atypical      2,000-caloriediet. However, the statement also explained that mostof      this fluidcould be obtained via the liquid contained in foods.
    Regardless, the 8-glasses-a-day dictum caught on.Today people frequently      consume muchmore as they tote giant water bottles, buy super-sizesoft      drinks, andfollow programs that promise you can lose weight bydrinking      as much as aquart of fluid at a time.
    Also, those who choose to participate in such adiet may forget an important      fact ifthey’re coffee drinkers: Caffeine is a diuretic –it      encouragesthe kidneys to produce urine so effectively that it maycontribute      to milddehydration. In moderation, there is little to worry about;but      heavyconsumers of caffeine may find a faster flow of fluidsthrough      their body,requiring a greater consumption of non-caffeinated liquids.
    In a 2000 survey conducted for RockefellerUniversity and the International      Bottled WaterAssociation, 2,818 adults in 14 cities reporteddrinking      about 6 cupsof water a day—a result that was presented asalarming      evidence thatAmericans are becoming dehydrated. But if you includethe      sodas,coffee, tea, milk, juice, sports drinks, and alcoholicbeverages      theserespondents drank, their average fluid consumption was 17.6cups      a day—enoughto have you urinating every waking hour, even ifyou      don’t haveany problem with bladder capacity.
    More recently, a kidney specialist at DartmouthMedical School searched      thescientific literature for studies that might support the ideathat      people need 8glasses of fluid a day. Not only did he determinethat      no suchevidence exists, but concluded that the research that hasbeen      done"strongly suggests that such large amounts are not needed."
    Fluids and incontinence    If you havean incontinence problem, the below tips might helpimprove      yoursymptoms. Unless you engage in strenuous exercise or have amedical      condition(such as a propensity toward forming kidney stones) thatrequires      more fluidconsumption:
    Aim for no more than 6–8 cups of fluid (from allsources) each      day.
    Don’t drink more than 8 ounces at a time.
    Don’t guzzle. The faster your bladder fills, themore likely you      are to feelurgency.
    Minimize caffeinated and carbonated drinks.
    Decrease or eliminate alcohol consumption.
    If you are thirsty because it is hot or you haveexercised, don’t      hesitate todrink water.