Obesity is a serious health problem affecting approximately 30% of all Americans adults.  Since 1980, the number of obese and overweight adult Americans has roughly doubled, and tripled for children. Obesity is related to being overweight, but is medically defined differently.  So what does being obese mean exactly?  

Underweight = a person weights too little relative to height

BMI = 18.5 - 24.9

Overweight = a person weighs too much relative to height (weight from bone, fat, water, etc.)

BMI = 25 - 29.9

Obese = a person's body fat is too high relative to height

BMI = 30+

What is obesity?
Obesity simply means having too much body fat for your body. A measurement called the body mass index (BMI) is typically used to determine if a person is overweight or obese; this measurement usually is correctly associated with a person's body fat.  The BMI is calculated according to a person's weight, and their height.  

Becoming obese essentially means that a person is consuming more calories than is being used by the body; this can take place over weeks, months, or years.  In contrast to gaining weight, if more energy is spent than being taken in, than weight loss occurs.  And, if the amount of calories consumed equals the amount of calories being used, then a person's weight stays the same.