BMI Calculator

BMI is the common acronym given to Body Mass Index, a number calculated from your weight and height that roughly correlates to the percentage of your total weight that comes from fat, as opposed to muscle, bone or organ. The higher a person's BMI, the higher the percentage of fat in their body. If your BMI is under 20, you might be underweight. Between 20 and 25, you are probably at a good healthy weight for your height. A BMI over 25 is considered overweight, and over 35 is considered obese.

What are some limitations of BMI?

BMI has its limitations and some doctors and educators are lobbying for significant changes. The main limitation of BMI is that it only takes into consideration weight and height. Though it is a step above simply using a person’s weight to determine health, there are many factors left out of the BMI calculations.

For example, a person’s bone density and size are not taken into consideration. Some people are referred to as big-boned. This is not just an alternate term to fat, as some people believe. There are actually different bone sizes and densities within people. This is determined by ethnicity, family history, and other factors. Bone density is not taken into consideration when determining a person’s Body Mass Index.

Muscle mass is also not taken into consideration. A body builder may have little to no fat on their body, but their BMI number may indicate that they are overweight because of the size and mass of their muscles. Just as with bones, muscle mass is different in different people. On the other hand, a person may be determined healthy by BMI but have no muscle mass to their body. Muscle to fat ratio is an important factor that is left out of these calculations.

Harmful habits such as smoking, drinking, and drug use are other important factors outside the realm of body mass. A person may be classified as healthy due to BMI, but actually be very unhealthy and at high risk do to lifestyle choices. The same goes for family history. A person with a normal body weight as determined by BMI may be a risk for heart disease or cancer due to family history, exposure, or other factors.

Conclusions of Using Body Mass Index

Though the application of BMI for individuals was not the purpose of those who invented and expanded on the calculations, it has become a popular and effective determining factor used by many people. However, it should not be the only determining factor and it should not be used as the only indicator in an overall fitness program.

Knowing your Body Mass Index is an appropriate starting point for weight loss, as a way to maintain a healthy weight, as well as a way to increase weight in those who are underweight. When the limitations are taken into consideration and other factors of health are assessed, BMI can be a fair assessment of a person’s weight and health.

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