A BMI or Body Mass Index is a measure of body fat based on height and weight that applies to both men and women. BMI can be used to indicate if you are under weight, normal weight, overweight, obese, or morbidly obese. BMI is an estimate of body fat and used as a gauge of your risk for diseases associated with your body weight. Certain diseases such as heart disease, type 2 diabetes, high blood pressure, gall stones, breathing problems and certain cancers occur more in people who have a high BMI.
Find out you BMI through this link BMI Calculator
So what do those numbers mean?
A normal BMI is 18.5 to 24.5 and indicates a bodyweight with low chances of developing disease such as diabetes and heart disease. However research shows that even within the so called "normal" range the risk for developing type 2 diabetes, heart disease and several types of cancer starts to rise towards the upper end starting as low as a BMI of 21. The World Health Organization states that a BMI of 18.5 to 24.9 should be maintained for optimal health.
A BMI of 24 is associated with twice the heart disease risk as someone with a BMI of 18.5.
Ideal BMI appears to be between 20-22 , and a BMI of 20-25 is associated with the longest lifespan.
People with a BMI of 25 to 30 or "overweight" are at 30 percent greater risk for heart disease compared to the "normal" weight BMI (Journal of American College of Cardiology.
A BMI of 40 and higher is associated with the loss of a decade of life or more.
Waist Circumference
Both BMI and waist circumference can be used to predict the risk of death due to excess body fat, but even with a "normal" BMI there is an increase in mortality when the waist line widens.
There is no universal guideline for measuring the waist line, Michael Gregor MD writes in his book 'How Not to Diet' that the halfway point between the top of the hip bones and the bottom of the rib cage appear to be the most effective at tracking changes of fat over time.
A healthy waistline cut-off where increased risk of metabolic complications starts is at waistlines of 31.5 for women and 37 for most men, and 35.5f or Chinese, Japanese and South Asian men. Dr Gregor also recommends to keep your waist less than half your height
Normal weight obesity is someone who has a normal BMI but who carries fat around the middle and may have up to twice the risk of dying compared to someone who's overweight or obese according to their weight and height. This is why both the World Health Organization, the national Institute on Health and the American Heart Association recommend measuring both BMI and waist circumference.