What is BMI (Body Mass Index)
Body mass index (BMI) is a number based on body weight in relation to your height that indicates how much your weight affects your risks for weight-related health problems. It doesn’t directly measure body fat. For adults, there’s no difference in BMI weight ranges for age; health risks appear to be the same, regardless of age. The same chart applies to men and women.
The generous BMI range of healthy weights allows for individual differences. Higher weights within the healthy range typically apply to people with more muscle and a larger frame, such as many men and some women. After all, muscle and bone weigh quite fat. Gaining or losing weight within these ranges isn’t necessarily healthful for you.
People with a higher percentage of body fat tend to have a higher BMI than those who have a greater percentage of muscle. Carrying excess body fat puts you at greater risk for health problems such as heart disease, diabetes, certain cancers, and high blood pressure. The higher your BMI, the bigger your risk.
How to Calculate BMI?
Calculate your BMI
- Multiply your weight in pounds times 703
- Divide that by your height in inches.
- Divide that by your height in inches again!
Or skip the calculations; check the BMI chart.
If you fit within the healthy range BMI 18.5 to 24.9 that’s good. Take steps to keep it there, especially if your BMI starts to creep up. Be aware: some people fit within the healthy range but still have excess body fat and little muscle.
What if your BMI is above 25? For most people, that’s less healthy unless the extra weight is muscle, not fat. Try to avoid more weight gain. The higher your weight is above the healthy range, the greater your risk for weight-related problems.
What if your BMI falls below “healthy”? That may be okay for you, but it also may suggest a health problem. A BMI under 18.5 may indicate increased risk for menstrual irregularity, infertility, and osteoporosis. It also may be an early symptom of a health problem or an eating disorder. Check with your health professional if you lose weight suddenly or unexpectedly.
Use the BMI only as a guideline. Age, gender, and ethnicity impact how BMI relates to body fat. For people who have lost muscle mass, including some elderly people, even a BMI within the “healthy” range may not be healthy. Healthy muscular people may have a BMI above the healthy range. Consult your doctor about the BMI that’s healthy for you.
Your BMI alone doesn’t determine whether your weight is healthy. The location and amount of body fat you carry, and your weight-related risk factors, including your family history of health problems, count, too.
Body Weight, Body Fat?
Your body composition (how much of your weight is body fat), not necessarily where you fit on any chart, is an important part of evaluating your weight. In fact, the location and amount of body fat may predict your weight-related health risk more than bodyweight alone. For example, a person’s BMI may fit right within the healthy range, but he or she still may carry too much body fat. Conversely, a muscular person may seem to be at increased risk according to charts, but may not be overfat. Why? Muscle weighs more than fat.
How can you determine how much of your weight is body fat (often referred to as percent body fat)? Short of expensive tests such as underwater weighing, getting an exact measure isn’t easy, and it’s especially hard to figure it out on your own. A health or fitness professional might use a skinfold caliper to measure the fat layer on several parts of your body, such as your arm, midriff, and thigh. New electronic scales and other devices also can measure body fat percentages.
Your weight on a scale by itself can’t tell you if you’re carrying too much fat and how your weight is distributed. Most importantly, body weight shouldn’t dictate how you feel about yourself.
Health risks go up as waist size increases. That’s especially true if your waist measures more than 35 inches for a woman or more than 40 inches for a man. So a simple tape measure is a tool for assessing abdominal fat. Stand, and measure your waist just above your hipbone.
Hint: Relax, breathe out. Don’t cinch in the tape measure or pull in your stomach!
Note: After menopause, many women tend to add weight around the midriff.
RISK OF ASSOCIATED DISEASE ACCORDING TO BMI AND WAIST SIZE
|BMI||WAIST LESS THAN OR EQUAL TO
40 IN. (MEN) OR 35 IN. (WOMEN)
|WAIST GREATER THAN
40 IN. (MEN) OR 35 IN. (WOMEN)
|18.4 or less||–||N/A|
|30.0 -34.9||High||Very High|
|35.0 -39.9||Very High||Very High|
|40 or greater||Extremely high||Extremely high|
This post contains the content of the book American Dietetic Association Complete Food and Nutrition Guide 3RD EDITION