When dealing with obesity, or any other kind of weight problems, certain numbers measuring the ratio of a person's weight and height will come up. The body mass index (BMI) is one of the most recognized and reliable indicators used today to identify possible weight problems. It is a scale system that applies to both men and women, regardless of age or frame size. On the other hand, when it comes to children and teens, the interpretation of BMI is both age- and sex-specific.

BMI is an inexpensive and practical screening tool used to measure body fat. The simple calculations are indirect and should not be viewed as a professional diagnostic tool. If a person shows a high BMI, he or she should consult a healthcare provider for further assessment. This may include skin-fold thickness measurements, diet evaluations, physical activity, family history review, and other appropriate health screening evaluations.

Using the metric system, the formula for BMI is weight (kilograms) divided by height (meters) squared. Formula: weight (kg) / [height (m)]². Imperial system users can calculate their BMI by dividing weight in pounds (lbs) by height in inches (in) squared and then multiplied by a conversion factor of 703. Formula: weight (lb) / [height (in)]² x 703. For those unfamiliar with the formula, many free BMI calculators can be found online.

Underweight people usually have a BMI below 18.5, while a normal BMI is between 18.5 and 24.9. Overweight people have a BMI between 25 and 29.9, and the BMI of an obese person is over 30. A BMI greater than 40 is considered morbidly obese. BMI does not account for muscle mass, which is heavier than fat, and therefore can give questionable results in women who are pregnant or breastfeeding, competitive athletes, body-builders and people with chronic illnesses.

The Body Mass Index (BMI) is an important fat content indicator and needs to be monitored closely. Except for a few exceptions, if the BMI numbers are elevated, and remain high, it can signify the risks of developing obesity-associated diseases, hypertension, high cholesterol, or high blood sugar, and even death. Also, the fact that a BMI result falls into the 'normal' range does not mean someone’s health is perfect. A normal BMI plus truncal obesity (localized fat deposits, usually settled in the torso and abdomen) can put a victim at risk of developing cardiovascular diseases, as well as type II diabetes mellitus.

If you are concerned about your health focus on adopting a healthy lifestyle and not just on numbers. Be more physically active and exercise regularly. Watch your weight and diet closely, evade fried foods, include supplements and avoid destructive habits, such as smoking, alcohol and drug abuse.