Assessing Your Weight and Health Risk
Assessment of weight and health risk involves using three key measures:
Body mass index (BMI)
Waist circumference
Risk factors for diseases and conditions associated with obesity

waist_measurement

Body Mass Index (BMI)
BMI is a useful measure of overweight and obesity. It is calculated from your height and weight. BMI is an estimate of body fat and a good gauge of your risk for diseases that can occur with more body fat. The higher your BMI, the higher your risk for certain diseases such as heart disease, high blood pressure, type 2 diabetes, gallstones, breathing problems, and certain cancers. Although BMI can be used for most men and women, it does have some limits: It may overestimate body fat in athletes and others who have a muscular build. It may underestimate body fat in older persons and others who have lost muscle. Use the BMI Tables to estimate your body fat. The BMI score means the following:
 
BMI : Underweight Below 18.5 
           Normal 18.5–24.9  
           Overweight 25.0–29.9 
          Obesity 30.0 and Above 

Waist Circumference
Measuring waist circumference helps screen for possible health risks that come with overweight and obesity. If most of your fat is around your waist rather than at your hips, you’re at a higher risk for heart disease and type 2 diabetes. This risk goes up with a waist size that is greater than 35 inches for women or greater than 40 inches for men. To correctly measure your waist, stand and place a tape measure around your middle, just above your hipbones. Measure your waist just after you breathe out.

Risk Factors for Diseases and Conditions Associated With Obesity
Along with being overweight or obese, the following conditions will put you at greater risk for heart disease and other conditions:
Risk Factors
High blood pressure (hypertension)
High LDL cholesterol ("bad" cholesterol)
Low HDL cholesterol ("good" cholesterol)
High triglycerides
High blood glucose (sugar)
Family history of premature heart disease
Physical inactivity
Cigarette smoking

There are risk factors such as age and family history that you cannot change, so you need to make sure that we are lowering the ones that we can!  For people who are considered obese (BMI greater than or equal to 30) or those who are overweight (BMI of 25 to 29.9) and have two or more risk factors, it is recommended that you lose weight.  Even a small weight loss (between 5 and 10 percent of your current weight) will help lower your risk of developing diseases associated with obesity. People who are overweight, do not have a high waist measurement, and have fewer than two risk factors may need to prevent further weight gain rather than lose weight.
Talk to your doctor and a fitness professional to see whether you are at an increased risk and whether you should lose weight. They will evaluate your BMI, waist measurement, and other risk factors for heart disease and suggest an active program and balanced diet for healthy living. The good news is even a small weight loss (between 5 and 10 percent of your current weight) will help lower your risk of developing those
diseases.

This information was adapted from the Aim For A Healthy Weight article at the National Heart Lung and Blood Institute.