Body Mass Index (BMI): The Weight of One Number

Dr. Kirk Sahagian, Bariatric Surgeon

Whether you’re dieting toward a certain weight goal or just trying to eat healthier, remember that good health is about more than looking good poolside or hitting a magic number on the scale.

Being overweight increases your risk of developing a host of chronic conditions and diseases that can impact your quality of life and shorten your lifespan. People who are overweight are at increased risk for diabetes, heart disease, high cholesterol, stroke, high blood pressure, gallbladder disease, osteoarthritis, sleep apnea and other breathing problems, and some forms of cancer, including breast, colorectal, endometrial, and kidney.

The impact of obesity on longevity of life has been well documented. Worldwide, over 2.5 million deaths can be attributed to obesity annually, with more than 400,000 deaths in the United States alone. This is second only to cigarette smoking. An obese individual’s risk of death can be up to 40 times that of a nonobese individual of the same age and gender. Only one in seven obese individuals will reach the US life expectancy of 76.9 years. In the morbidly obese population, average life expectancy is reduced by 9 years in women and 12 years in men.

Calculating your Body Mass Index (BMI) is an inexpensive and easy start for measuring your overall health and can be done at home using BMI calculators available on the internet. BMI is a measurement of your weight in relation to your height and indicates your total body fat. Although BMI does not directly measure body fat, research has shown that your BMI score is a reliable indicator, especially when combined with a measurement of your waist circumference. These scores, combined with information about any other risk factors you may have, indicate your likelihood of developing weight-related disease, and can calculate a patient’s status as “overweight” or “obese.”

Remember, your BMI measurement is only one factor used to calculate your risk for obesity related chronic disease. While it provides an accurate indication of body fat, a BMI reading may not provide the full picture of a person’s health or risk level in specific instances. BMI can differ according to a person’s race, sex or age. It is important for you—and your physician—to examine other health indicators to get a true picture of your health.

Patients who take the time to calculate their BMI will often wonder what to do if their BMI falls between 25-29.9 “overweight,” 30-39.9 “obese, " or >40 “morbidly obese.” The answer is very simple: talk to your primary health care provider. For patients with a BMI between 25 and 35, your doctor may recommend a combination of a low calorie diet, increased exercise and possibly medications. For those with a BMI between 35 and 39.9, who also have weight-related illness such as high blood pressure, asthma, obstructive sleep apnea, or gastroesophageal reflux disease, the recommendation may include all the above therapies as well as surgical therapy. Patients with a BMI >40 would benefit from all of these therapeutic options and qualify for weight loss surgery with or without weight-related illness.

If you are overweight or obese a treatment plan is important. It starts with a consultation with your primary health care provider.