BMI Calculator

BMI, or Body Mass Index, is a scale used to gauge a person’s body fat in relation to their weight (in kg or lbs) and height (in meters or ft.). The scale categorizes individuals as underweight, healthy, overweight, and obese. This is helpful in medicine, as unhealthy BMI score can indicate certain health problems.  



In this post, we discuss BMI, its calculation, what healthy BMI is, and the limitations of the BMI scale. Additionally, we also elaborate on certain lifestyle changes and eating habits you can adopt for better health.

What Is Body Mass Index or BMI?

Fat, carbohydrates, and proteins are the three essential macronutrients; fat is considered one of the most important determinants of fitness.

Body mass index (BMI) is one of the several inexpensive ways to gauge general health. Although it does not directly measure body fat, the formula is strongly correlated with the fat content of the body.

The BMI scale is divided into different ranges or BMI categories, each of which specifies whether you are underweight, healthy, overweight, or obese.

Even though the scale is not the perfect indicator of health conditions, it can help determine if you are possibly facing metabolic disorders and require further lab tests.

How Does the BMI Calculator Work?

BMI formula, simply put, is a ratio of weight divided by height:

BMI = weight (kg) / height (m2)

When using English measurements, i.e., weight pounds (lbs) and height inches squared (in2), the resultant weight-to-height ratio should be multiplied by 703 (to convert to the standard kg/m2 unit).

BMI Table For Adults

BMI is not specific for all ages. Instead, people 20 or older are grouped as adults. The following table demonstrates the Centers for Disease Control and Prevention (CDC) classification of body mass index or BMI categories for adults:

[table id=1 /]

Take your weight-to-height ratio, and check which of the four ranges it falls in to know about your BMI category.

BMI For Children

People aged 2 to 20 are placed in one group. For this age group, body mass index or BMI is calculated as a percentile.

[table id=2 /]

Special growth charts have been designed for the purpose. You plot the weight and height on the graph, and then check the corresponding percentile (marked on the graph).

Necessary Actions For Better Health

Here are some general tips to achieve and maintain healthy weight:

  • Eat healthily: In case you are underweight or overweight /obese, consult an experienced nutritionist for an appropriate diet plan
  • Exercise regularly: Remember that exercise is for everybody (no matter what your current weight is). However, in case you’re not healthy as per BMI standards, it is better to get a professional trainer to attain a healthy weight.
  • Limit alcohol consumption: Alcohol prevents normal catabolism (breakdown) of fats which leads to unhealthy weight gain.
  • Avoid smoking: Smoking has been shown to increase metabolic rate, i.e., it accelerates the breakdown of nutrients while also reducing the absorption of calories. This reduces appetite, which eventually leads to weight loss.
  • Avoid added sugar: Diet high in sugar increases body fat. Additionally, it is also associated with insulin and leptin resistance. This leads to the development of diabetes, increase in appetite, and several other health problems.

Limitations Of BMI

Although body mass index (BMI) is widely used as a health metric in medical practice, it has certain limitations. These have led to arguments about BMI not being an accurate indicator of general health.

Here are the main reasons why BMI is not the perfect predictor of health:

Does Not Factor In Race

BMI was created with data from European individuals. While the role of race in terms of body weight is not clearly understood, research hints at a correlation between the two.

Does Not Account For Water Weight, Muscle Mass, And Bone Density

Apart from fat content, water weight, the muscle mass and bones also amount to body weight. However, these are not considered crucial health markers.

You cannot distinguish body fat from the other three with BMI value, which can give inaccurate results. For example, muscles are denser than fat, and in builders or athletes, the extra muscle mass can lead to a BMI that is considered overweight category (even though the said individual is generally healthy).

This is one of the primary reasons why the BMI chart is argued to be an incorrect scale to check the possibility of the development of metabolic and other disorders.

Body Fat Distribution

The BMI chart does not count in fat distribution.

The distribution of fat content in the body is of critical importance when determining health complications. For example, high amounts of fat in the upper body are linked to hypertension, diabetes mellitus, and heart complications like premature coronary death.

On the other hand, excessive fat deposition in the lower body is associated with the risk of sleep apnea, metabolic syndromes, bone diseases, etc.

Alternatives For BMI

As we have discussed previously, high BMI value corresponds with high fat content, which is one of the major risk factors for several metabolic diseases and CVDs like coronary heart disease. Similarly, lower BMI also points to nutritional deficiency and absorption disorders.

Therefore, it is oftentimes crucial to get further tests for more accurate results.

Some of them are as follows:

  • Waist circumference
  • Weight scales
  • DEXA or Dual-energy X-ray absorption metric (the gold standard for accurate measurement of body composition)

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