Source: National Institutes of Health
If you’re trying to determine if you need to lose weight or how much weight you need to lose, calculating your body mass index (BMI) is a great place to get started. Body mass index is simply a number that uses a formula to determine if you are a healthy weight for your current weight. A BMI chart for women lists out all heights and weights on a color-coded grid that will allow you to visually see where your BMI stands.
The first step you need to do to see where your body compares to standard averages on a BMI scale is to actually determine your body mass index. To do this there are many helpful tools online but it can be manually done by determining what your pound (not kg) weight is and multiplying it by 703. Once you have that number divide it twice by your height in inches. For example, if you weighed 150 pounds and were 62 inches tall, this is how you would calculate your BMI: 150 * 703 / 62 / 62 = 27.43. So you would have a BMI of 27.43.
Once you have your BMI, you can compare it to a BMI chart for women and see how your BMI relates to your recommended weight. First find your height on the chart and then follow that row until you find your BMI number. For someone that is 62 inches tall (5 feet 2 inches) with a 27.43 BMI, they would fall in the overweight category, becoming very close to the obese range.
On average if you have a score that is below 18.5, you are considered underweight. With a BMI between 18.5 and 24.9 almost every BMI chart for women that you see will consider you normal or “ideal”; if your BMI is higher than 25 you are in the overweight category with 30+ being obese.
While your body mass index can be a very powerful tool in helping determine if you are overweight, it’s important to note that there are certain factors that aren’t taken into consideration when calculating BMI with just your height and weight. For example the amount of muscle you have is not considered; by just using height and weight a person with low body fat and high muscle mass can actually fall into the “overweight” category even though they are very fit. For the most accurate BMI reading you can have a nutritionist perform a caliper test. For most women, though, you will be able to get a general idea of whether or not you need to lose (or gain) weight with a simple BMI test.