Facts
More than one-third of adults and almost 17% of youth were obese in 2009–2010.
In 2009–2010, 35.7% of U.S. adults were obese.
In 2009–2010, 16.9% of U.S. children and adolescents were obese.

How important is for you to know your BMI?

http://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/english_bmi_calculator/bmi_calculator.html