The Body Mass Index (BMI) is one of many ways to measure and determine the level of excess fat you may have in your body. It is not the most accurate of measurements and many other ways such as hydrodensitometry (underwater weighing), skin-fold measurements (using calipers) and magnetic resonance imaging will provide more accurate determinations of body fat. However, BMI can be useful in most cases to give you a general idea of where your ideal body weight should be. There will be cases, though, in which it is not. For instance, a body builder or athlete with a large muscle mass will have a high BMI even though they do not have a high amount of body fat. The point is, for most of us it is a useful tool for measuring and gives us a good indication of a healthy weight.
How to Calculate Your BMI
Your BMI is a simple ratio of your weight and height. More specifically, BMI is calculated using the following formula:
BMI = weight (kg) / (height [m])2
As you can see, this formula is based on the metric system, with weight in kilograms and height in meters. So to calculate your BMI based on height in inches and weight in pounds, multiply the result by 703.
BMI = 703 x weight (lbs.) / (height [in.])2
Interpreting Your BMI
BMI scores for average individuals are generally ranked as follows:
| Condition | BMI |
| Underweight | Below 18.5 |
| Normal | 18.5-24.9 |
| Overweight | 25.0-29.9 |
| Obesity | 30.0 and above |
| Morbid Obesity | 40.0 and above |
Again, it is important to note that BMI scores do not always properly estimate the level of body fat in certain individuals. As stated earlier, athletes and others with muscular builds, for example, may fall into the overweight category despite having near perfect physiques. It is also important to note that the elderly and those who have lost muscle mass may fall into the underweight category as well despite having excess body fat.
Another thing to be aware of is that BMI assessments vary by sex and age. BMI scores for boys are slightly lower than for girls (aged 7-16), and scores for women are slightly lower than for men (aged 18 and up).
Despite these caveats, for most people, the BMI is a simple and useful tool that can be used for determining disease risk due to excess fat.
Risk Factors Associated with High BMI
There are a number of risk factors linked to high BMI scores that put individuals at significant risk for diabetes, heart disease, high blood pressure, gall bladder disease and some types of cancer. These include:
- High LDL cholesterol (considered “bad” cholesterol)
- Low HDL cholesterol (considered “good” cholesterol)
- High blood sugar
- High triglycerides
- Sedentary lifestyle
- Smoking
Lowering Your BMI
Obviously in order to lower your BMI you must decrease you body fat and overall weight. This typically means modifying your diet and how you eat as well as exercising. These are two things that we highly recommend but also suggest you consult with a doctor before embarking on anything too drastic. We talk with patients on a daily basis about weight, not only how it affects their health but also how it can be contributing to some of the conditions they see us for, such as back pain or knee pain. With that in mind, we decided to implement a new program called ChiroThin to help patients lose weight and begin a new and healthier lifestyle. If you are looking to shed some pounds, we highly recommend you look into this program. If you have any questions, don’t hesitate to ask anyone working at our office. Every one of us here has gone through this program with great results.
