BMI Chart

There are many ideas as to what a healthy body looks like. Many people often compare what they see in the mirror to the images shown in the media via television shows, movies, commercials, and magazines. However, these images don’t always portray what health experts deem as a healthy body. A body mass index, or BMI, chart was created to help individuals determine if their body falls into a weight range that is considered healthy. The chart is relatively easy to use as the chart contains various heights and weights that once matched correlate to a specific BMI value. Knowing one’s BMI is useful as it can give individuals an insight as to if they have a healthy weight, and if not, just how close they are to their ideal weight. Using a BMI chart can guide individuals to tailoring their nutrition and fitness plans based on their current condition.

BMI Chart Formula

BMI charts are readily available online, especially as a part of health and nutrition websites. The BMI chart was created from a mathematical formula where an individual’s body mass in kilograms is divided by the square of a person’s height in meters. Those residing in the United States typically use pounds for weight measurements and inches for height measurements. Thus, most American websites will make this substitution for ease of reading the BMI charts. The formula is an attempt to estimate the amount of fat, muscle, and bone in a person based on their height and weight, and consequently, place them in a weight category using this information.

Using a BMI Chart

A BMI chart is constructed in the shape of a square that contains a left column that lists heights, a top row that lists the BMI value, and the inner part of the chart that lists a variety of weights. The left column that lists heights begins with the smallest height and increases to the greatest height. The range of values consists of the most common heights in the population that often starts at about 4 feet and 8 inches and extend to about 6 feet and 4 inches. Depending on the chart used, the height value can be expressed in either inches, centimeters, or feet with inches. BMI value range from 15 to 60. However, since this range includes extreme values that are not commonly seen in most populations, most BMI charts do not list this entire range. It’s most common to see BMI values on a chart range from about 19 to 35. Consequently, the weight values in the middle of the chart do not include every possible value but rather the values that are most common in the population. To determine an individual’s BMI, the user must locate their height from the left column, and then advance across the corresponding row until their weight is found in the middle part of the table. Once the single location is found, the user must locate the BMI value listed above the location in the very top row of the chart.

BMI Categories

Eleven total BMI categories exist although many charts do not include the most extreme categories. The very severely underweight category includes BMI values up to 15. The severely underweight category includes BMI values from 15 to 16. The underweight category includes BMI values from 16 to 18.5. The normal or healthy weight category includes BMI values from 18.5 to 25. The overweight category includes BMI values from 25 to 30. The obese class I or moderately obese category includes BMI values from 30 to 35. The obese class II or severely obese category includes BMI values from 35 to 40. The obese class III or very severely obese category includes BMI values from 40 to 45. The obese class IV or morbidly obese category includes BMI values from 45 to 50. The obese class V or super obese category includes BMI values from 50 to 60. The obese class VI or hyper obese category includes BMI values over 60.

BMI Accuracy

Many discussions have arisen regarding the accuracy of using BMI charts. Some health experts disagree with the calculation of some of the values towards the two extremes of the chart with the argument that some shorter people are assigned lower BMI values that makes them think they have less fat than they do while taller people are assigned higher BMI values that make them think they have a greater amount of body fat than they actually do. Another argument is that the chart does not take into account the different body types such as having a small, medium, or larger body frame. For example, if a person has small body frame, the BMI chart might inaccurately indicate that the person has a healthy weight when in reality they may be overweight whereas a large frame person of the same weight and height would accurately be considered a healthy weight. The BMI chart is also known to overestimate body fat for those with a greater lean body mass and underestimate body fat for individuals with a lesser amount of lean body mass. For example, a bodybuilder with a large amount of lean body muscle mass may easily be considered overweight by the BMI chart, which would be inaccurate.

The BMI chart can be a great tool for getting an overall picture of an individual’s health for most people in a given population. However, users must understand what the BMI value represents and take into account its limitations.