According to the Centers for Disease Control and Prevention, 20 to 30 percent of the American population has a body mass index, or BMI, measurement of 30 or greater, which means nearly a third of the population is obese. While many obese people understand the health benefits of losing weight, they don't necessarily understand BMI or what their ideal weight should be.
Body Mass Index
BMI is a calculation based on your height and weight. It's an accepted measurement to identify if a person is too heavy or underweight. However, BMI is just a tool for calculating a person's level of fat. It does not indicate or diagnose health issues that may be related to being underweight, overweight or obese. Individuals with a BMI of 18.5 to 24.9 are in the healthy weight range, according to the CDC. Under 18.5 is considered underweight, which carries health risks, as well. A BMI over 24.9 but under 30 is overweight, and over 30 is obese.
How to Calculate BMI
The formula for calculating BMI is BMI equals weight times 703 divided by height squared. For example, if you're 5 feet tall and weigh 150 lbs., your BMI would be (150 x 703) / (60 X 60) or 105,450/3,600 = 29.29.
How To Calculate Ideal Weight
Knowing your BMI can help you determine if your weight is appropriate for your height. If you discover you weigh too much or too little, you can also use your BMI to calculate your ideal weight using basic algebra. First you need to determine your goal BMI number. Using the BMI formula, plug in your numbers to solve for weight. For example, if your BMI goal is 20, the formula would be ideal weight = (Goal BMI x height squared) / 703. Using the previous example, the calculation would be (20 X 3,600) / 703 = 102 lbs. The example reveals that this 5 foot, 150-lb. person needs to lose 48 lbs. to reach a BMI of 20.
Limitations of BMI
BMI is a useful tool but is not fool-proof. In addition to not providing any information regarding health-related issues, it also doesn't factor in the difference between muscle and fat weight. A muscular athlete may get a high BMI reading but not have much fat. The reverse can be true, as well, in which a person may be over-fat but not have much muscle or weight and therefore have a lower BMI measurement.
References
- Centers for Disease Control and Prevention: U.S. Obesity Trends
- Centers for Disease Control and Prevention: About BMI for Adults
- What Health: How to Calculate BMI
- National Heart Lung and Blood Institute: Calculate Your Body Mass Index
- National Heart Lung and Blood Institute: Assessing Your Weight and Health Risk
Member Comments