本集內容
Is BMI an accurate way to measure obesity?
用 BMI 指標判斷肥胖的方法對嗎？
文字稿
Have we been measuring obesity wrongly?
被我們用來判斷肥胖的方法是否有誤？
The most common way of doing it is using BMI, or Body Mass Index, which calculates whether someone is a healthy weight for their height.
最常用的判斷肥胖的指標是 BMI，即身體質量指數，它通過計算得出一個人的體重相對於身高是否健康的結論。
For many adults, a BMI over 25 is considered overweight, and anything over 30 is obese.
對許多成年人來說，身體質量指數大於 25 即被視為超重，大於 30 即被視為肥胖。
This can vary depending on our ethnic background.
但這也取決於我們的族裔背景。
BMI is a quick and easy method supported by the World Health Organization, but it has limitations.
用身體質量指數判斷胖瘦程度既快速又簡便，這個方法得到瞭世界衛生組織的認可，但它也有局限性。
It can’t measure the difference between fat, muscle and bone.
它無法區分體內脂肪、肌肉和骨骼之間的差異。
And as humans age, muscle declines and fat builds up around the waist, often with no change in weight.
隨著人們年齡增長，肌肉比例會減少，脂肪會堆積在腰部，而體重卻往往沒有變化。
This is one of the reasons why many studies have suggested different cut-off points of BMI over the years.
這就是為什麼多年來許多研究都建議針對每個年齡段設定不同的臨界值的原因之一。
Source: University of Tor Vergata
Researchers in Italy scanned people aged between 40 and 80 to work out their body fat percentage.
數據來源：羅馬第二大學
意大利的研究人員對年齡在 40 至 80 歲之間的人群進行瞭身體掃描，以計算出他們的體脂率。
They found significantly more people were considered obese using this method than would have been using BMI.
他們發現，在使用體脂率計算方法後，更多的人會被判定為肥胖。
The researchers say that we should lower our definition of obesity for this age group to a BMI of 27, but further work will be needed to confirm the results of the study.
研究人員表示，對這個年齡段的人來說，身體質量指數在 27 以上時就應判定為肥胖，但還需要進一步的研究工作來證實這個研究結果。
For now, it’s much cheaper to calculate BMI than it is to measure body fat percentage, so it’s unlikely we will ditch the former any time soon.
目前，計算身體質量指數要比測量體脂率的成本低得多，因此我們不太可能在短期內舍棄身體質量指數這個指標。
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