They're both around the same height, weight, and consequently, they have the same Body Mass Index — or BMI.

他們兩位有著相似的身高、體重，所以，他們有著相同的身體質量指數－簡稱 BMI

But if you split them open Damien Hirst style

但如果你利用達米恩·赫斯特風格來區別他們

or just compare the results of their body scans you can see a slight difference.

或是比較他們全身檢查的結果，你可以發現些微的不同處

Phil has more body fat than Coleman, and Coleman has more muscle than Phil.

Phil 的體脂肪比 Coleman 多，而 Coleman 的肌肉比 Phil 多

Although BMI is a popular measure to assess if a person's weight might be putting them at risk for obesity-related diseases, its results can be pretty misleading and less nuanced than we'd like.

雖然身體質量指數是一個常見的測量方式，來衡量是否人類的體重是否過胖，會不會引起肥胖相關的疾病，但身體質量指數的結果會很容易讓人誤會，而且不夠準確性

So the BMI is an index that looks at somebody's body weight divided by their height.

所以身體質量指數是指一個人的身高除以體重所得的指數

So the formula is the body weight in kilograms divided by the height in square meters.

所以公式就是體重 (公斤) 除以身高 (公尺) 的平方

18.5 and below is underweight, 18.5 to 24.9 is your healthy range, 25 to 29.9 is overweight, and a BMI over 30 is classified as obese.

小於 18.5 為過輕，18.5 至 24.9 是標準體重，25 至 29.9 為過重，而 BMI 超過 30 為過胖

With the idea being that the taller somebody is, the more they should weigh.

我們都以為一個人越高，他們就應該會比較重

Kinda weird how a single decimal point can separate being overweight from being obese.

過重和肥胖之間就只差一個小數點是有點不合理的

The major problem with using BMI as a marker of health when it comes to body weight, because it penalizes you if you have a lot of muscle and you're healthier.

用身體質量指數作為健康依據的最大問題是，當我們提到體重時，如果你強壯又健康，對你是不利的

Let"s use professional athlete Marshawn Lyncwh as an example.

我們舉職業運動員馬孝恩·林奇為例

He's 5'11, 215 lbs, and his BMI is 30.

他 180 公分 、96 公斤，而他的身體質量指數為 30

He'd be categorized as obese.

所以他被歸類為肥胖型

That is because BMI doesn't distinguish muscle from fat.

這是因為身體質量指數並未區分脂肪中所含的肌肉指數

We are really concentrating on how much muscle does somebody have, because muscle it's the metabolic engine.

我們就只專注那個人有多少肌肉，因為肌肉是新陳代謝的幫浦

It's the thing that burns calories and the more muscle you have

它能夠燃燒卡路里，所以你體內的肌肉組織越多，

the easier it is for you to stay at a lower and

越是能燃燒更多熱量，並能保持一個較低和

more healthy body fat percentage not necessarily a BMI.

健康的體脂肪指數，不一定要以身體質量指數為依據

In this way, BMI's reliability as an indicator of health breaks down for athletes like Lynch.

這樣的方式，對於運動員馬孝恩·林奇而言，以健康為依據的身體質量指數失去了信服力

There are several more variables that can influence the interpretation of BMI.

還有許多變數會影響身體質量指數的結果

Things like age, gender, and ethnicity.

像是年齡、性別、和種族

While BMI is a useful measure for a large population study, for example,

對絕大數的研究而言，身體質量指數是個實用的測量方式，例如

to compare relative obesity rates from state to state;

比較城市和城市之間的肥胖比率

it becomes more problematic when you use it to determine an individual's health.

尤其當你用來測量一個人健康時會變得更有問題

The body mass index was introduced in the early 19th century.

身體質量指標是在早期 19 世紀提出的

This guy who created the formula — I'm so sorry, I'm gonna butcher his name,

一個傢伙創造這個公式－對不起，我不會唸他的名字

Lambert Adolphe Jacques Quetelet — wasn't even a physician.

朗伯·阿道夫·雅克·凱特勒－根本不能算是一位醫生

Quetelet was a Belgian mathematician.

凱特勒是一位比利時數學家

And his reason for creating the formula was to study the “normal man”, not obesity.

而他創造了這公式來研究「普通的人」，而沒考慮到肥胖

Its use shifted to study obesity because of Ancel Keys.

因為安賽・基斯，他則轉而研究肥胖

In 1972, Keys used the formula in his "Indices of Relative Weight and Obesity” study, renamed

在 1972 年，基斯運用他在「體重和肥胖的相關指數」一書提到的運算方式，重新命名

the formula to body mass index, and from there the “new” measure caught on among researchers.

身體質量指數，而之後這樣「新的」測量方式則被其他研究者運用

Over the years, its use in the health professional field grew and it's pretty much stuck around since.

多年下來，這計算方式在健康專業領域上蓬勃發展

It's easy to use, cheap, fast, and its right about 80% of the time.

計算方式很簡單、便宜、又快，並且有 80 百分比的正確性

So even though BMI has stuck around for more than 200 years,

即使身體質量指數流傳長達了 200 多年，

it's not the be-all and end-all indicator.

並不能算是一個完完全全的依據

There are more effective ways to assess to body composition, and overall health.

還有其他有效的方式可以來評估身體的組成，以及身體健康狀況

Hydrostatic weighing, or underwater weighing, is an option.

水中量重法，或是水底秤量法是個選擇

Along with MRI scans, and waist-to-hip ratio.

和核磁共振成像、以及腰臀比例

Medical tests like checking blood pressure, your glucose levels, resting metabolic rate,

檢康檢查像是血壓檢查、葡萄糖指數、基礎代謝率，

can further give a picture of overall health.

可以讓我們更了解整個身體的健康狀況

I went to George Washington University, and lab director Todd Miller showed me another way,

我去了一趟喬治·華盛頓大學，而實驗室的主管托德·米勒介紹我另一個方法，

using dual-energy x-ray absorptiometry or DEXA image.

運用雙能量 X 光吸光式測定儀或簡稱為 DXA影像

It measures total body composition, including fat mass, lean body mass, and bone density.

它可以測量出身體的總組合，包刮了脂肪重量、去脂肪體重、以及骨頭密度

So the green is the areas where the body is very lean.

所以綠色部分是身體過瘦的地方

The yellow areas of moderate fat.

黃色部分是身體有著適當脂肪的地方

And the red areas of high fat.

而紅色地方指的是身體有過多脂肪的地方

So this person was here July 3rd she had 72 pounds of fat and 109 pounds of muscle.

這個人是 7 月 3 號來檢查的，她有 33 公斤的脂肪和 49 公斤的肌肉

And in December 27th of this year she had at thirty seven pounds of fat in 115 pounds of muscle.

而在今年 12 月27 號，她有 17 公斤的脂肪，而有著 52 公斤的肌肉

Using this chart you can see if this person stepped on a scale, they'd only see they lost 29 pounds.

用這個表格，你可以發現這個人量體重，會發現他們只瘦了 29 公斤

What the scale wouldn't say is that they gained six pounds of muscles,

而這個體重機並不會指出他們實際上長了 3 公斤的肌肉

and BMI wouldn't say that either.

身體質量指數的算法也是如此

So even if two people have similar BMIs,

所以就算兩個人有著相似的身體質量指數，

that one number will never truly give either of them

但這指數並無法明確指出他們任何一個人

the full picture of their overall wellbeing.

整體的身體健康狀況

BMI is an indirect measurement of one aspect of an individual's health.

身體質量指數是個參考性的測量一個人的健康方式

So while it can be helpful, it shouldn't be the only way to understand the human body.

雖然身體質量指數是有助於人，但還是有其他的計算方式可以運用來了解人體狀況