Body mass index (BMI) is a measure of body fat based on height and weight that is used to classify people as underweight, normal weight, overweight, or obese. It is calculated by dividing a person's weight in kilograms by their height in meters squared.
BMI Calculation Formula
BMI = weight (kg) / height (m)2
BMI Categories:
Underweight: BMI less than 18.5
Normal weight: BMI 18.5 to 24.9
Overweight: BMI 25 to 29.9
Obese: BMI 30 or greater
BMI Calculation Example
If a person weighs 70 kg and is 1.73 m tall, their BMI would be calculated as follows:
BMI = 70 kg / (1.73 m)2 = 23.41 kg/m2
A BMI of 23.41 is considered normal weight.
How to Use BMI
BMI is a useful tool for screening for weight-related health problems, such as heart disease, stroke, type 2 diabetes, and some types of cancer. However, it is important to note that BMI is not a perfect measure of body fat. It does not take into account muscle mass, bone mass, or body composition. For example, a very muscular person may have a high BMI even though they do not have a lot of body fat.
BMI is also not appropriate for everyone. It should not be used to assess the weight of children and adolescents, pregnant women, or people with certain medical conditions.
If you are concerned about your weight, talk to your doctor. They can help you determine if you are at a healthy weight and develop a plan to reach or maintain a healthy weight.
Limitations of BMI
While BMI is a useful tool, it has some limitations. It does not take into account:
Muscle mass: People with more muscle mass will have a higher BMI than people with less muscle mass, even if they have the same amount of body fat.
Bone density: People with higher bone density will have a higher BMI than people with lower bone density, even if they have the same amount of body fat.
Body composition: People with different body compositions may have different BMIs, even if they have the same amount of body fat. For example, a person with a lot of belly fat may have a higher BMI than a person with the same amount of body fat distributed more evenly throughout their body.
How to Use BMI More Accurately
To get a more accurate assessment of your body fat, you may want to use a combination of BMI and other measurements, such as waist circumference or body fat percentage. You can also talk to your doctor about other ways to assess your body fat.
Conclusion
BMI is a simple and widely used tool for assessing weight status. It can be used to screen for weight-related health problems and to track changes in weight over time. However, it is important to be aware of the limitations of BMI. If you are concerned about your weight, talk to your doctor.
Try out our BMI Calculator