HomeNutritionWhat is Body Mass Index for Women – Calculating and the Pros and Cons

what is body mass index for womenWomen more than any other facet of society are concerned with both weight and appearance. One of the tools at their disposal to better plan a healthy lifestyle is the Body Mass Index or BMI. With the rising numbers of cardiovascular and lifestyle-predisposed diseases, more and more people have been inclined to eat and live healthy. However, while eating well-balanced and healthy foods and exercising on a regular basis are considered to be markers of a healthy lifestyle, it doesn’t necessarily mean that you are healthy. For this reason, the National Institutes of Health released its Body Mass Index (BMI) guidelines in late June of 1998 to replace the outdated life insurance tables that were utilized as markers for a person’s weight. The BMI was created in order to ensure that dietitians, government agencies, researchers and doctors alike have the same standards of healthy weight in relationship to a person’s height. The best part: the same calculation is used for men, women and children.

How to Calculate Body Mass Index for Women

The calculation for BMI is not difficult and only requires basic math skills. The basic formula is weight in pounds divided by height in inches squared. This quotient is then multiplied by 703 to arrive at BMI.  For example: imagine a woman 5′ 5″ tall and she weighs 165 lbs.   Her height in inches is 65. So, the quick calculation:

(weight)/[height in inches²] x 703 = BMI

This is shown in two steps:

(165)/[65×65] = .039

.039 x 703 = 27.4, which is her BMI

Interpreting this number is easy, because the National Institutes of Health has also provided a reference range:

Underweight = less than 18.5

Normal weight = 18.5 to 24.9

Overweight = 25 – 29.9

Obesity = 30 and over

Our fictional woman in the example is in the middle of the Overweight range per the NIH. For comparison, in the United States, the average Body Mass Index of adults is 26.5.

Using an Obesity Chart

If a person hates doing the math, there is also a BMI Chart (commonly called an Obesity Chart) that can provide a quick approximation.

A sample one:

BMI 19 20 21 22 23 24 25 26 27 28
Height
(inches) Body Weight (pounds)
58 91 96 100 105 110 115 119 124 129 134
59 94 99 104 109 114 119 124 128 133 138
60 97 102 107 112 118 123 128 133 138 143
61 100 106 111 116 122 127 132 137 143 148
62 104 109 115 120 126 131 136 142 147 153
63 107 113 118 124 130 135 141 146 152 158
64 110 116 122 128 134 140 145 151 157 163
65 114 120 126 132 138 144 150 156 162 168
66 118 124 130 136 142 148 155 161 167 173
67 121 127 134 140 146 153 159 166 172 178
68 125 131 138 144 151 158 164 171 177 184
69 128 135 142 149 155 162 169 176 182 189
70 132 139 146 153 160 167 174 181 188 195
71 136 143 150 157 165 172 179 186 193 200

Using our same example, it is easy to move down the left column (height in inches) to arrive at 65. Then moving across to the weight, we pick either 162 or 168. At the top we can see this corresponds to a BMI of 27 or 28 depending upon which is chosen. Because our fictional example is squarely between the two weights, it is easy to say 27.5 for the BMI, which is extremely close to our calculated BMI of 27.4.

The Pros of BMI

The good thing about  BMI is that it’s a free tool that anyone can use. Some digital bathroom scales come with a BMI feature to calculate it automatically as you are weighed. It is a fast, easy, and inexpensive means of screening weight-related health problems that is within the a set range of standards. It provides consistent results no matter when or where it is calculated. It may also lead to lifestyle changes, too. When a person knows their BMI, they can change their lifestyle in order to pursue optimum health. For instance, studies show that people with 20 to 25 BMI are less likely to fall victim of early death while those with BMI of 27 and above are more likely to suffer from health problems.

The Cons of BMI

The drawback with BMI is that it doesn’t necessarily consider body composition. For instance, people with dense muscular builds and bones such as bodybuilders and other athletes are automatically labeled as overweight in the BMI scale when this is clearly not the case. Meanwhile, elderly people that experience low bone density may be marked as underweight. People who are different in terms of race and ethnicity may also be rated wrong in the BMI scale. There are even arguments that the chart should be separate for men and women due to a woman’s natural makeup which is far less muscular than a man’s.

The Body Mass Index for women is easy to calculate and provides a gauge of health, but it should only be one factor. This tool is not without its shortcomings and the labels that accompany the ranges can be mentally devastating. Any concerns regarding obesity should be discussed with a health professional.

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