The term “BMI” seems to be thrown around a lot when talking about weight, especially in relation to extra pounds. So should you be paying close attention to your own BMI? And is it more important to lower your BMI or to improve your fitness level?
So let’s start with the basics – what exactly is BMI? According to the Center for Disease Control and Prevention (CDC), BMI stands for Body Mass Index and is a reliable indicator of most people’s body fat content. Calculating a person’s BMI is inexpensive and easy to do, and can be used for determining weight categories that may be related to health problems (such as Type 2 diabetes). However, BMI should not be used as a diagnostic tool. “For example, a person may have a high BMI. However, to determine if excess weight is a health risk, a healthcare provider would need to perform further assessments,” the CDC website reported. “These assessments might include skinfold thickness measurements, evaluations of diet, physical activity, family history, and other appropriate health screenings.” Potential health consequences for being overweight and obese include Type 2 diabetes, gallbladder disease, osteoarthritis, sleep apnea and respiratory problems, and some cancers.
The CDC lists four standard BMI status categories for adults. These categories and their BMI levels are:
- Underweight – a BMI of below 18.1.
- Normal – a BMI between 18.5 and 24.9.
- Overweight – a BMI between 25.0 and 29.9
- Obese – a BMI between 30.0 and above.
However, these categories can be a little misleading depending on the person being analyzed. For instance, even if they have the same BMI, women tend to have more body fat than men. Additionally, older people often have more body fat than younger adults, even if they share the same BMI level. And a larger BMI score in highly trained athletes may be due to muscle instead of body fatness.
So should you obsess about lowering your BMI or instead focus on improving your fitness level? One new study suggests the latter is the better move. This new study out of the University of South Carolina followed 14,345 adult men who were mostly white, in the middle or upper class and who on average were 44 years old. The participants, who underwent at least two comprehensive medical exams during the study, were asked to take part in treadmill tests to estimate their physical fitness (maximal METs); additionally, their height and weight were measured to calculate their Body Mass Index (BMI). Changes in BMI and physical fitness were assessed over a six-year period.
Interestingly, the researchers found that maintaining or improving fitness was associated with a lower risk of death, even if the men’s BMI has not changed or increased. The researchers also found that every unit of increased fitness (measured as the metabolic equivalent of task or MET) over six years was associated with almost a 20% lower risk of heart disease and stroke-related deaths and a 15% lower risk of death from any cause. MET, which is a ratio of a person’s metabolic rate during a specific physical activity as compared to a reference rate of the metabolic rate while at rest, is used to measure the intensity of aerobic exercise.
“This is good news for people who are physically active but can’t seem to lose weight. You can worry less about your weight as long as you continue to maintain or increase your fitness levels,” said Dr. Duck-chul Lee, a physical activity epidemiologist at USC’s Arnold School of Public Health.
So what should you do? Although I’m not a medical expert, I’d probably take Dr. Lee’s advice and focus on maintaining or improving one’s fitness level, with a secondary focus of lowering one's BMI. I believe the body is a wonderful organism and keeping it fit will help it continue to work optimally. So get moving!
Published On: December 13, 2011