Instance of using SI - Calculating BMI

In the following posts we will use some instances to let us know how to use SI. In this post we will know BMI and how to calculate it.

BMI stands for body mass index. It is a measure of relative size based on the mass and height of an individual. The index was devised by Adolphe Quetelet during the course of developing what he called "social physics", between 1830 and 1850. The BMI for a person is defined as their body mass divided by the square of their height-with the value universally being given in units of kg/m². So if the weight is in kilograms and the height in metres, the result is immediate, if grams and centimetres are used, a conversion factor of 10 (kg/m²)/(g/cm²).

    BMI = mass(kg)/(height(m))² = 10× mass(g)/(height(cm))²

The BMI of an individual may also be determined using a table or chart which displays BMI as a function of mass and height using contour lines or colors for different BMI categories, and may use two different units of measurement.

There are a wide variety of contexts where the BMI of an individual can be used as a simple method to assess how much the recorded body weight departs from what is healthy or desirable for a person of that height. There is, however, some debate about which values on the BMI scale the thresholds for 'underweight', 'overweight' and 'obese' should be set.

The modern term "body mass index" (BMI) for the ratio of weight to squared height owes its popularity to a paper published in the July 1972 edition of the Journal of Chronic Diseases by Ancel Keys. This found the BMI to be the best proxy for body fat percentage among ratios of weight and height. The interest in an index that measures body fat came with increasing obesity in prosperous Western societies. BMI was explicitly cited by Keys as appropriate for population studies and inappropriate for individual evaluation. Nevertheless, due to its simplicity, it has come to be widely used for preliminary diagnosis. Additional metrics, such as waist circumference, can be more useful.

BMI ranges from underweight to obese and is commonly employed among children and adults to predict health outcomes. The BMI trait is influenced by both genetic and non-genetic factors, and it provides a paradigm to understand and estimate the risk factors for health problems.

BMI provides a simple numeric measure of a person's thickness or thinness, allowing health professionals to discuss weight problems more objectively with their patients. BMI was designed to be used as a simple means of classifying average sedentary (physically inactive) populations, with an average body composition. For these individuals, the current value recommendations are as follow: a BMI from 18.5 up to 25 may indicate optimal weight, a BMI lower than 18.5 suggests the person is underweight, a number from 25 up to 30 may indicate the person is overweight, and a number from 30 upwards suggests the person is obese. Athletes, who tend to have an atypical muscle/fat ratio (atypical body fat percentage), may have a BMI that is misleading at first sight.

A frequent use of the BMI is to assess how much an individual's body weight departs from what is normal or desirable for a person of his or her height. The weight excess or deficiency may, in part, be accounted for by body fat (adipose tissue) although other factors such as muscularity also affect BMI significantly (see discussion below and overweight). The WHO regards a BMI of less than 18.5 as underweight and may indicate malnutrition, an eating disorder, or other health problems, while a BMI greater than 25 is considered overweight and above 30 is considered obese. These ranges of BMI values are valid only as statistical categories:

• Very severely underweight:  < 15
• Severely underweight: 15~16
• Underweight: 16~18.5
• Normal: 18.5~25
• Overweight: 25~30
• Obese Class I (Moderately obese): 30~35
• Obese Class II (Severely obese): 35~40
• Obese Class III (Very severely obese): > 40

After reading this post, please comment as this format:

Height: ____ m or ____ cm
Mass: ____kg or ____ g
BMI: ____ kg/m²
Category: ________

Example:

Height: 1.8 m
Mass: 70 kg
BMI: 21.6 kg/m²
Category: Normal