BMI definition always related to relationship between weight and height that is associated with body fat and health risk.Your first step to find out if you are at a healthy weight is to find out what your BMI, or body mass index is and what your waist size is. For most people, these are good clues to whether they are at a healthy weight.If your weight is not healthy, your risk for weight-related problems is higher, including high blood pressure, heart disease, stroke, arthritis, diabetes, and some forms of cancer. BMI chart tells you the recommended weight range for your height.The chart assigns a number, or BMI, to your weight. Calculate your own BMI using this formula:
- If your BMI is less than 18.5, you are in the underweight category. Talk to your doctor to find out if your weight is a symptom of a medical problem. Your doctor can also refer you to a nutrition expert who can help you learn about healthy eating.
- If your BMI is between 19 and 24.9, you are in the recommended weight range for your height. But your health may still be at risk if you are not getting regular physical activity and practicing healthy eating.
- If your BMI is 25 to 29.9, you are in the overweight category. This may or may not be unhealthy, depending on some other things, like your waist size and other health problems you may have.
- If your BMI is 30 or higher, you're in the obese category. You may need to lose weight and change your eating and activity habits to get healthy and stay healthy. See the topic Obesity.
If you are Asian, your recommended weight range may be lower. Talk to your doctor. It's important to remember that your BMI is only one measure of your health. A person who is "overweight" according to BMI charts, but not "obese" may be healthy if he or she has healthy eating habits and exercises regularly. People who are thin but don't exercise or eat nutritious foods aren't necessarily healthy just because they are thin.
After you know your BMI, it's time to look at your waist size. Measuring your waist can help you find out how much fat you have stored around your belly. People who are "apple-shaped" and store fat around their belly are more likely to develop weight-related diseases than people who are "pear-shaped" and store most of their fat around their hips. Diseases that are related to weight include diabetes, heart disease, and high blood pressure.Measure your waist size with a tape measure. The tape should fit snugly but not press into your skin. For most people, the goal for a healthy waist is:
- Less than 40in. for men.
- Less than 35in. for women.
If you are Asian, the goal for a healthy waist is:
- Less than 36in. for men.
- Less than 32in. for women.
| If you are ... | Then ... |
| In the underweight range on the BMI chart: | See your doctor to find out if you have a medical problem that is causing your low weight. |
| Within the recommended BMI range and your waist size is within the recommendations: | Your weight is not a problem for your health.
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| At or above the recommended BMI range and your waist size is higher than recommended: | See your doctor to find out if you have health problems that might be related to your weight. You may need to change your eating habits and get more active. |
| In the overweight category on the BMI chart but your waist size is within the recommendations: | Your weight may be right for you. But you need to see your doctor to find out if you have health problems that might be related to your weight.
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| In the obese category on the BMI chart, no matter what your waist measurement is: | You may need to lose weight to be healthier, as well as change your eating and activity habits. |
Your doctor may want to take another measurement, called a waist-to-hip ratio. This measurement is a comparison of your waist size to your hip size. A higher waist-to-hip ratio means that you are more "apple-shaped" than "pear-shaped" and therefore at a higher risk for weight-related disease. Body fat testing is sometimes used to help find out if a person has a healthy percentage of body fat. But it can be inaccurate. It also costs more than measuring BMI or waist size. So it's rarely used to measure a person's risk for weight-related diseases.