Overweight and Obesity Information: Definition of Overweight and Obesity Based on Body Mass Index (BMI)

Being overweight and obesity are medical conditions which involve an accumulation of excess body fat. Studies on weight and other obesity information indicate that carrying excess weight can accelerate your aging and shorten your life.

Obese and overweight people have a greater risk for cancer, diabetes, stroke and other health problems. Abdominal fat or belly fat is a predictor of risk for obesity-related diseases and weight-related health risks.

What is the definition of overweight and obesity based on Body Mass Index (BMI)?

Body Mass Index (BMI) is a widely used method for estimating body fat. BMI is calculated by dividing the person's weight by the square of his or her height. It is used to define whether a person is overweight or obese.

• An adult with BMI of 25 or higher is considered overweight.
• An adult with BMI of 30 or higher is considered obese.

BMI correlates with amount of body fat, but it does not directly measure body fat. So, it's not a good way to estimate body fat for some people. For example, body builders and pregnant women may be classified as overweight based on their BMI even if they do not have excess body fat.

Another problem with using BMI is that it does not determine different location and distribution of body fat; For example, a person with a lower BMI may be classified as "healthy," but have a lot of abdominal fat; belly fat is associated with increased health risks.

There are other ways of estimating a person's body fat:

• Ultrasound
• Waist circumference
• Skin-fold thickness
• Computed tomography
• Waist-to-hip circumference ratio
• Magnetic resonance imaging (MRI)

For determining a person's likelihood of developing obesity-related diseases, the National Heart, Lung, and Blood Institute recommends the use of two other predictors in addition to BMI:

• The person’s waist circumference and measurement of abdominal fat.
• Other risk factors for obesity-related diseases, such as, level of physical inactivity or high blood pressure.
  

Stress management as well as following healthy eating habits and increasing physical activity can help prevent obesity and being overweight. Healthy weight management can decrease risk for cancer, diabetes, stroke and other diseases associated with overweight and obesity.