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Getting the Skinny on the BMI By Steve Tomsic Let us start out with a small bit of history. The BMI is a formula that calculates weight categories based on a comparison of total body weight to height. It is an inexpensive measurement method that is easy for clinicians and the general population to use. The BMI allows people to compare their weight to that of the general population. A British team of researchers studied 7,700 men over 15 years. They found that a BMI of 22 is optimal for an average, healthy man. To achieve a BMI of 22, a man who is 6 feet tall would be very lean, weighing just 162 pounds. The researchers found that men with BMI’s greater than 22 experienced more health problems. This is how a baseline for the BMI was established. The BMI ranges, according to the American Society for Bariatric Surgeons, are as follows: Underweight = 18.4 or less Normal weight = 18.5 to 24.9 Overweight = 25 to 29.9 Obese I = 30 to 34.9 Obese II = 35 to 39.9 Morbid Obesity = 40 and above Many of the men that have contacted me were bothered by the BMI’s most apparent pitfall—it does not take into account the composition of body weight. For many healthy men and women, this means that it fails to recognize that muscle mass, which weighs more than fat tissue, may make a person weigh more than the ideal or “normal? weight as determined by BMI charts because he or she has a large amount of heavier muscle tissue. It is possible that the BMI has become the new scale for a person with weight problems. Those of us that have had weight loss surgery may focus too heavily on the BMI number, as many of us have with the scale, instead of focusing on our overall health. The BMI was created to make it easier to categorize weight. Those that use it and support it acknowledge that it is not a diagnostic tool by itself. According to the CDC (Centers for Disease Control and Prevention) other methods to measure your size and to predict possible health problems are: • Diet (what are you eating?) • Physical Activity (how active are you?) • Waist Circumference (anything over 40 inches in men, and 35 inches in women, • Blood Pressure (high blood pressure can be related to higher than normal weight) • Blood Sugar Level (high sugar levels are associated with obesity) • Cholesterol Level (high cholesterol is associated with poor diet and higher than normal weight) The CDC reports two common myths about the BMI. One is that the BMI measures body fat. It does not. Two people can have the same BMI and different percentages of body fat. The other is that the BMI is a diagnostic tool. It is not. It is one tool to discover risk factors for disease and pre-mature death. The BMI should be used with other tools to determine over all health. It is true that the BMI does not take lean muscle mass into account when assessing weight categories. Many men who have had surgery mistake this for a reason to question the BMI. What many pre-op and post-op men do not realize is that it is unlikely that someone who qualified for weight loss surgery would have a large amount of lean muscle mass, as a weight lifter or body builder would. Healthy bodies simply do not weigh enough to fall into the morbidly obese BMI range. The news-journal.com reports that while the BMI applies to both men and women regardless of their age, frame size or muscle mass, these values do not apply to athletes, body builders, pregnant or nursing women or the elderly and children. The reality is that we must be careful not to take the BMI to either extreme: regarding as our ultimate guide or disregarding it because of its obvious faults. It is a good indicator for health, but should be considered in conjunction with the other elements the CDC highlights as weight-related risk predictors. All of us must also realize that a seemingly healthy BMI does not mean we are healthy. Again, we need to consider a wide range of health indicators. Is our diet healthy? Is our physical activity enough? Do you know what your blood pressure, blood sugar and cholesterol levels are? The NIH (National Institute of Health) reports that you should assess your weight related risks by measuring your BMI, your waist circumference and other conditions associated with obesity (reported above as high blood pressure, high cholesterol and high blood sugar.) As an example, a man with a BMI in the overweight range who has a waist circumference under 40 and does not have other risk factors may only need to maintain his weight as opposed to losing weight. They recommend talking this over with your doctor when it comes time to assess your health. Gender difference is often a topic when questioning the accuracy of the BMI. For its general use as a comparison, there are no differences established between men and women. One argument is that men have more muscle mass than women. Another is that women are supposed to have a slightly higher percentage of body fat than men. Again, the BMI is a very general tool used in conjunction with other indicators to assess a person’s health. There are tests for body fat and muscle mass, but they tend to be expensive and not covered by health insurance. If you are interested in these, seek advice from your physician and insurance company. The weight loss surgery patient is unique. We must always consider that all of these predictors and indicators are created in reference to the general population. We are inundated with BMI numbers throughout our weight loss surgery experience, but we must remember that even though this number is extremely important to medical practitioners and insurance companies, it is only one tool on the workbench of weight loss, health and weight management. www.fitwatch.com |
