BMI
The term BMI stands for Body Mass Index. It was first developed in 1830 by a Belgian by the name of Quetelet who was interested in math and physics. It was never meant to measure body fat, but to create criteria for the expression of body size. In other words, underweight, normal, overweight, and obese were the terms to correlate to the number derived from the formula weight (in Kilograms) divided by height (in meters) to the second power or squared.
Perhaps it is better explained by this formulaic BMI=mass(kg) divided by height (meters)squared. There is a nomogram here for you to utilize in order to calculate your BMI. It appears here.
Ancel Keys was an important influence on the use of the BMI measurement. In 1972 he suggested it was appropriate for population studies and inappropriate for individual diagnostic value. Even though it is inappropriate for determining body fat, health risk, or how high your health insurance premium should be; it is used for exactly that purpose. (Keys was the advocate for the "fat/ heart hypothesis" claiming it was dietary fat that caused heart disease.) The WHO has used the BMI rating to create obesity statistics since 1980.
One problem with the BMI is a very tall person will have a high BMI rating. Look at basketball players. They are very tall and have a lot of lean muscle. The BMI rating will be showing in the obese range (27-40) even though the percent of body fat is 7% or less. The inverse is true when there are short people with a normal weight.
Body Fat composition may be determined by the use of a reactance and impedance device we now find on our bathroom scales. It may be off by a percent, but overall this is the best way to determine if you have a degree of fat accumulation problem. For women body fat by percent should be 25-28% and men should have 10-15% body fat.
The findings today suggest that the abdominal fat mass is the indicator of health risk, and the determination of obesity. The abdomen should be measured at the level of the belly button. For women the measurement should be 32 inches or less. For men the measurement should be 40 inches or less. In most individuals the fat mass is centralized inside the abdominal cavity. It is most dense at the level of the belly button. When fat is stored in the abdominal cavity, it acts like an endocrine organ secreting hormones.
These hormones create an auto-immune process that we recognize as Insulin Resistance. The hormones are called 'cytokinines' and they repel insulin. This in turn creates the need to produce more insulin to remove blood sugar, thus creating adult onset diabetes.
The waist to hip ratio is determined by dividing the waist measurement by the hip measurement. It is considered 'normal' for men if that number is 0.9 or below, and 0.85 or below for women. The BMI is considered normal when it is between 18.5 and 24.9.
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