Assessing Weight Status: What is Body Mass Index (BMI)?

体重和身高之间的体重指数（BMI）关系最初是在1940年代初由美国大都会人寿保险公司精算师开发的。

它用于评估死亡的风险，因此计算人寿保险费。他们的数据表明，与高度相比，与高度相比，与高度相比，体重更重的人的死亡风险更大（尤其是心血管疾病）。

这些BMI桌子（尽管从1940年代进行了更新，但仍然是通过使用简单的人体测量法（身体）措施从超重评估健康风险的最广泛接受的方法之一。

许多人熟悉BMI，以表明成年人的体重是否健康。BMI基于您的体重与身高之间的关系，并由dividing你的body weightinkg由你height squaredmeasured in仪表：

BMI = body weight (kg) / height (m²）

BMI概念与身高有关，其与死亡风险的关系现已在许多长期研究中得到验证。与BMI在健康范围内的人相比，在肥胖范围内具有较高BMI的人的死亡风险要大得多。

随着BMI的增加，风险增加。因此，公共卫生信息努力鼓励人口将其BMI保持在健康范围内。

Adult BMI ranges which describe ‘weight’ status

下表提供了通常用于描述成年高加索人群超重和肥胖的“截止”值。

Body Mass Index	<19.5	20 to 24.9	25至29.9	30 to <35	35至39.9	>40
（kg/m2）	体重不足	健康的体重	Overweight	肥胖1级	肥胖2级	肥胖3级

^{注意：“病态肥胖”一词有时用于描述BMI> 40 kg/m的人2who are considered at very high risk of illness or death due to their excess weight.}

Known shortcomings

While BMI cutoffs are widely used, some shortcomings are known and should be highlighted:

• 它们仅与成年人有关。儿童需要不同的BMI临界值来评估他们的风险，就像老年人和患有慢性疾病的人一样。
• Different ‘cutoffs’ are also used for different ethnicities, for example, in Asian and Aboriginal people. This is due to differences in bone structure and differing levels of disease risk when overweight or obese.
• BMI is based only on body weight and does not distinguish between body muscle and body fat. So some individuals who are very muscular may have a BMI in the overweight range and yet have a normal level of disease risk.
• BMI does not distinguish where body fat is deposited. Risk is much higher when fat occurs around the abdomen

周向估计疾病风险的重要性

人们在我们的中央身体区域周围沉积的脂肪通常是人们注意到他们变得超重的第一件事。

有证据表明，沉积在腹部上的脂肪比沉积在腿部，手臂或臀部上的脂肪增加了健康风险。

For this reason, interest has grown in measuring waist and hip circumferences. This is easily done using a simple tape measure. Either the waist circumference alone or the ratio of waist circumference to hip circumference (distinguishing an ‘apple shape’ from a ‘pear shape’) are used to estimate health risks.

不同类型的脂肪

As we now learn more about what factors increase our risk of disease and in particular the health issues around obesity, the role of different types of body fat has become clarified. In essence, our bodies have two different types of fat: subcutaneous fat and visceral fat.

Visceral fat is laid down around our main organs in our abdomen, in particular around the liver, pancreas and kidneys. Once thought to be inert and not metabolically active, we now recognise that visceral fat produces inflammatory agents that drive metabolic disturbance.

Those people who tend to lay down fat around their abdomen (‘apple shape’) have more visceral fat and tend to have a greater risk of developing Type 2 diabetes, cardiovascular disease and stroke.

So, the measurement of waist circumference has become a useful and quick indicator of this disease risk.

我们知道的

More recently nutritionists have become interested in the ratio of Waist circumference to Height. Evidence shows that people with a high waist circumference compared to their height have a greater disease risk than people with a lower waist circumference compared to their height.

与BMI不同，相同的腰围与高度比率可以与不同的种族一起使用，也可以用于儿童。

关于腰到高度的有用的回家消息是“保持腰部到一半的高度”。

Using risk indicators

所有健康风险和超重措施的措施主要用于检查整个群体或人群的风险。它们是易于执行的措施，便宜地用于大量人。但是他们不太擅长估计个人的实际风险水平。

要找出一个人在身体上有多少脂肪以及这种脂肪的沉积位置，我们需要使用更复杂的方法来告诉我们身体成分。

什么在...

Our bodies are comprised offour不同的隔室是：水，脂肪，瘦组织（肌肉）和矿物质（骨骼）。我们体内的脂肪和瘦（肌肉）量存在性别差异，男性比大多数女性的瘦瘦比例更高，脂肪比例更高。

可用技术

为了测量这些不同的隔室或我们的“身体成分”，我们需要使用比磁带测量更复杂的方法。与BMI或腰部相比，对人体成分的度量可能更有信息：高度比：它可以提供有关它们拥有多少身体脂肪的细节，并启用更量身定制的方法来评估或降低患糖尿病的风险或心血管疾病。

人体组成的一种参考方法是双能X射线吸收仪（DXA），它可以准确地衡量该人拥有的实际脂肪，肌肉和矿物（骨）以及其在其体内的位置。

Remember that the visceral fat located around the abdomen where the main body organs are located is the sort of fat that is particularly associated with the common chronic diseases that lead to premature death.

These scans can be helpful at an individual level to monitor the effectiveness of diet and or exercise on body fat and on lean or muscle. In weight loss, what we ideally want to achieve is a reduction in body fatness with preservation of lean or muscle mass.

评估身体成分

如果您想了解有关身体成分评估的优势的更多信息，请考虑参加这项活动。

1. 访问此document with scans of two young women谁也一样BMI在“正常范围”内，但身体组成却非常不同。
2. 检查扫描 - 您认为哪个人更有可能患有心血管疾病的风险更大？
3. 考虑一下对身体成分的知识是否有助于这些女性，以及饮食和或活动是否可以用于改变其体内脂肪的％。