Do you know your Body Mass Index? If you don’t, you can use a BMI calculator available online or you can calculate it yourself, using this formula:
BMI = Weight (kg) / Height (m) ².
So, now that you know your BMI, what are you going to do with it?
What’s a normal BMI?
A normal BMI is between 18.5 and 25; a person with a BMI between 25 and 30 is considered overweight; and a person with a BMI over 30 is considered obese. A person is considered underweight if the BMI is less than 18.5.
As with most measures of health, BMI is not a perfect test. For example, results can be thrown off by pregnancy or high muscle mass, and it may not be a good measure of health for children or the elderly.
So then, why does BMI matter?
In general, the higher your BMI, the higher the risk of developing a range of conditions linked with excess weight, including diabetes, arthritis, liver disease, several types of cancer (such as those of the breast, colon, and prostate), high blood pressure (hypertension), high cholesterol, sleep apnea.
According to the WHO, nearly 3 million people die yearly worldwide due to being overweight or obese. In addition, independent of any particular disease, people with high BMIs often report feeling better, both physically and psychologically, once they lose excess weight.
And here’s why BMI may not matter
It’s important to recognize that BMI itself is not measuring “health” or a physiological state (such as resting blood pressure) that indicates the presence (or absence) of disease. It is simply a measure of your size. Plenty of people have a high or low BMI and are healthy and, conversely, plenty of people with a normal BMI are unhealthy. In fact, a person with a normal BMI who smokes and has a strong family history of cardiovascular disease may have a higher risk of early cardiovascular death than someone who has a high BMI but is a physically fit non-smoker.
And then there is the “obesity paradox”. Some studies have found that despite the fact that the risk of certain diseases increases with rising BMI, people actually tend to live longer, on average, if their BMI is a bit on the higher side.
Actually, this should come as no surprise. BMI, as a single measure, would not be expected to identify cardiovascular health or illness; the same is true for cholesterol, blood sugar, or blood pressure as a single measure. And while cardiovascular health is important, it’s not the only measure of health! For example, the study did not consider conditions that might also be relevant to an individual with an elevated BMI, such as liver disease or arthritis. In addition, more recent studies suggest that those who are healthy and overweight or obese are more likely to develop diabetes or other negative health consequences over time.
As a single measure, BMI is clearly not a perfect measure of health. But it’s still a useful starting point for important conditions that become more likely when a person is overweight or obese. It’s a good idea to know your BMI. But it’s also important to recognize its limitations.
Empower your wellbeing and reconnect with your best you!