Know Your Body
Body Mass Index (BMI)
Centers for Disease Control and Prevention 2015
Body Mass Index (BMI): is a number calculated from a person's weight and height. BMI is a fairly reliable indicator of body fatness for most people. BMI does not measure body fat directly, but research has shown that BMI correlates to direct measures of body fat, such as underwater weighing and dual energy x-ray absorptiometry (DXA). BMI can be considered an alternative for direct measures of body fat. Additionally, BMI is an inexpensive and easy-to-perform method of screening for weight categories that may lead to health problems.
For children and teens, BMI is age- and sex-specific and is often referred to as BMI-for-age.
To the left there is an Adult BMI Calculator and to the right is a Child & Adolescent BMI Calculator, courtesy of the CDC.
Overweight vs. Obesity
World Health Organization 2015
BMI is commonly used to classify overweight and obesity in adults. The WHO definitions:
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Overweight: a BMI greater than or equal to 25
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Obesity: a BMI greater than or equal to 30
In 2014, more than 1.9 billion adults (18+) were classified as overweight; with over 600 million of those adults classified as obese.
The worldwide prevalence of obesity more than doubled between 1980 and 2014.
Childhood Obesity
World Health Organization 2015
Defined based on the WHO growth reference for school-aged children & adolescents:
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Overweight: one standard deviation body mass index (BMI) for age and gender
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Obese: two standard deviations body mass index (BMI) for age and gender
Childhood obesity is one of the most serious public health challenges of the 21st century, with an estimated 42 million overweight children globally under the age of five (in 2013).