BMI - Body Mass Index

The body mass index (BMI) is a calculated number, based on height and weight, used to compare and analyse the health effects of body weight on human bodies of all heights. It was developed by the Belgian polymath Adolphe Quetelet in the course of working out his system of "social physics", between 1830 and 1850 (and is therefore also known as the Quetelet Index). It is equal to the weight, divided by the square of the height:

Typically, the weight is in kilograms and the height in metres, and the unit kg/m2 is often left out. (Using imperial units this is 703.07 times the weight in pounds, divided by the square of the height in inches.)

BMI is a common means of measuring overweight and obesity in humans. However, there are some concerns that BMI does not always present an accurate picture of these issues in individuals and populations.

Human bodies rank along the index from around 15 (near starvation) to over 40 (morbidly obese). This statistical 'curve' is usually described using more familiar categories, for easier comprehension by health professionals; eg, severe underweight, underweight, optimum weight, pre-obese, obese, morbidly obese. The exact index values used to determine weight categories vary from authority to authority, but in general a BMI less than 18.5 is underweight and may indicate malnutrition, an eating disorder, or other health problem, while a BMI greater than 25 is overweight and above 30 is considered obese. These range boundaries apply to adults over 20 years of age.

The U.S. National Health and Nutrition Examination Survey of 1994 indicates that 59% of American men and 49% of women have BMIs over 25. Extreme obesity — a BMI of 40 or more — was found in 2% of the men and 4% of the women.
Body mass index calculations are not just for adults—they can also be used to identify the growing number of overweight children. BMI for children aged 2 to 20 years is calculated just as it is for adults, but it is classified differently. Instead of set thresholds for underweight and overweight, it is their BMI percentile that is important. For children, a BMI that is less than the 5th percentile is considered underweight and above the 95th percentile is overweight. Children with a BMI between the 85th and 95th percentile are considered to be at risk of becoming overweight.

The following are common definitions of BMI thresholds:

For Males:
• Underweight: less than 20 (<20)
• Ideal: greater than or equal to 20 but less than 25 (>=20 but <25)
• Overweight: greater than or equal to 25 but less than 30 (>=25 but <30)
• Obese: greater than or equal to 30 (>=30)

For Females:
• Underweight: less than 18 (<18)
• Ideal: greater than or equal to 18 but less than 23 (>=18 but <23)
• Overweight: greater than or equal to 23 but less than 30 (>=23 but <30)
• Obese: greater than or equal to 30 (>=30)

See also:
• Obesity
• Complications of Obesity

• Sleep Apnea

• Plastic Surgery
• Abdominoplasty
• Liposuction
• Mesotherapy

• For financing of health procedures.
• For patient loans.

• This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Body Mass Index".