Definition of Obesity
Obesity is the over accumulation of adipose tissue (fat). In broad terms, a persons body mass index or BMI is used to indicate the level of body composition. In more finite terms, obesity is measured by the body fat percentage.
BMIStatistician Adolphe Quetelet invented the Quetelet Index of Obesity, which measured obesity in terms of BMI. BMI is caculated by dividing a person's weight (in kilograms) by the square of his or her height (in inches).
If your BMI is over 30, you are considered obese. A BMI over 40 is considered morbidly obese and a BMI over 50 is considered super obese. Some very lean countries that have very low obesity rates classify obesity as a BMI over 25 (japan) or a BMI over 28 (China).
There are weaknesses in BMI. It isn't accurate for everyone. For example, athletes can be very fit and show up as obese. That is why fat percentage is probably a more accurate way to define obesity.
Measuring Your Body Fat Composition
You can find your body composition of body fat with fat calipers, hydrodensitometry, near infrared interactance (NIR), dual emery x-ray absorptiometry (DEXA), MRI, bioelectrical impedance, and more. Most people use fat calipers (anthropometry), or biolectrical impedance due to the low cost.
Obesity Fat Percentages
According to The American Council of Exercise, a fit woman should have 21-24% body fat and a fit man should have 14-17% body fat. Athletes will typically drop four percentage points from the upper range of a generally fit person. For example, women athletes are 14-20% and men athletes are 6-13%. The acceptable range is 25-31% for women and 18-25% for men. Obesity for women is over 32% body fat and for men over 25%.
Obesity is linked to heart disease, many forms of cancer, psychological distress from discrimination, and shortened life span. Many people will gain significant health advantages by losing as little as ten pounds. If you are obese, you should take it seriously. It has serious health risks.