Body mass index (BMI) is an estimate of body fat based on height and weight. It doesn’t measure body fat directly, but instead uses an equation to make an approximation. BMI can help determine whether a person is at an unhealthy or healthy weight.

高BMI可以是身体上脂肪太多的标志，而低BMI可以是身体上脂肪太少的标志。一个人的BMI越高，发展某些严重病症的机会就越大，如心脏病，高血压和糖尿病。非常低的BMI也可以引起健康问题，包括骨质损失，免疫功能减少和贫血。

While BMI can be useful in screening children and adults for body weight problems, it does have its limits. BMI may overestimate the amount of body fat in athletes and other people with very muscular bodies. It may also underestimate the amount of body fat in older adults and other people who have lost muscle mass.

BMI is calculated by dividing a person’s weight by the square of their height.

The Centers for Disease Control and Prevention (CDC) provides a simple online儿童和青少年BMI计算器年龄2至19岁，和一个 成人BMI计算器 20岁及以上。

要计算BMI，您可以进入英尺和体重的高度。计算器还提供权重状态图表，以帮助您解释结果。

BMI is calculated the same way for people of all ages. However, BMI is interpreted differently for adults and children.

成人20岁及以上的成年人可以根据以下标准权重状态类别来解释他们的BMI。所有年龄和身体类型的男性和女性都是一样的：

BMI Weight Status
Below 18.5 Underweight
18.5 – 24.9 Normal
25.0 - 29.9 Overweight
30.0 and above Obese

BMI对ag)以下的人的解释是不同的e 20. While the same formula is used to determine BMI for all age groups, the implications for children and adolescents can vary depending on age and gender. The amount of body fat changes with age. It’s also different in young boys and girls. Girls usually acquire a higher amount of body fat and develop it earlier than boys.

儿童和青少年，CDC使用 年龄增长图表 to show BMI as a percentile ranking. Each percentile expresses a child’s BMI relative to other children of the same age and gender. For example, a child would be considered obese if they had a BMI that landed at or above the 95th percentile. This means that they have more body fat than 95 percent of children in the same age and gender category.

The following table shows the percentile range for each weight status:

百分位数 Weight Status
Below 5th Underweight
5至85日 正常或健康的体重
85th to 95th Overweight
95th and above Obese

根据这一点 National Institutes of Health , more than two in three adults are considered overweight and one in three are considered obese. About 17 percent of children and teenagers (ages 2 to 19) are considered obese.

人们因能源不平衡而获得体重。身体需要从食物中获得一定量的能量以便起作用。这种能量以卡路里的形式获得。当您每天使用或“烧伤”时，您的体重通常会保持通常相同的卡路里数量。如果您在燃烧比燃烧得多的卡路里，那么您将随着时间的推移而获得体重。

能源不平衡当然是重量增益的最大贡献者之一。然而，您的理想体重主要由遗传学确定，以及您吃的食物类型以及您的锻炼程度。如果您有一个高BMI，那么降低它很重要，所以你处于健康的体重状态。高BMI与发展严重健康状况的风险更大，例如：

  • 心脏病
  • high blood pressure
  • 肝病
  • osteoarthritis
  • 糖尿病
  • 中风
  • gallstones
  • 某些癌症，包括乳腺，结肠和肾癌

Anew study, however, indicates that body fat, not BMI, is more associated with the above health risks. You can lower body fat and get to a healthier weight by exercising at least three times per week. You should also follow certain diet habits, such as eating only when you’re hungry, eating mindfully, and choosing a diet that’s rich in whole, unprocessed foods. You may also benefit from nutritional counseling. A dietitian can teach you which foods to eat and how much food you should eat in order to lose weight.

正如高BMI可能导致健康问题，那么BMI都可以很低。缺乏足够的体脂可能导致：

  • 骨质损失
  • decreased immune function
  • 心脏问题
  • iron deficiency anemia

If you have a low BMI, discuss your weight with your doctor. If needed, increasing the amount of food you eat each day or reducing the amount of exercise can help you gain weight. A dietitian can also help you learn how to gain weight in a healthy way.