If we’re going to call a spade a spade, then the first line of the preamble should be edited to say: “We, the mostly obese people of United States…” Because let’s face it, we’re fat. Amongst industrialized countries, America is the fattest of them all, with two of every three American men considered to be overweight or obese. That may feel especially true today, since you probably gorged yourself on the day of supreme fatness otherwise known as the Super Bowl.
But here’s the thing: Obesity is one of those words that gets thrown around a lot, along with its most popular yardstick, the BMI, or Body Mass Index. So while you unbutton your fly and let your belly breathe, let’s talk about the actual definition of obesity. According to MedicineNet.com, “obesity has been more precisely defined by the National Institutes of Health (the NIH) as a BMI of 30 and above. (A BMI of 30 is about 30 pounds overweight.)”
Okay, I get it, I’m probably overweight. And I just ate enough buffalo wings to feed a small community of humpback whales, so my BMI is definitely up there. Or at least it might be — what exactly is BMI?
There he is. There’s my favorite average guy with above-average belly fat. According to the CDC, BMI is a person’s weight divided by the square of their height. So basically, the more chode-like your body appears, the higher the likelihood that you have a BMI above 30 (that’s not entirely scientifically accurate, but it’s close enough). Still, you should know that your BMI doesn’t measure your body fat directly, even though research suggests that it does correlate with the thickness of your skinfold (tasty!).
Okay, so — and I’m only asking this because I hate myself and I want to hate myself a little more — what would be considered a normal BMI?
The BMI sweet spot, according to Harvard Health, its anywhere 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,” reports Harvard Health. “A person is considered underweight if the BMI is less than 18.5.”
To put that into real height/weight context, if you’re a guy of average height (5-foot-10), by the BMI standard, if you weigh 210 pounds or more, you’re technically considered obese. And if you’re hoping to stay within the parameters of the BMI sweet spot (18.5 to 25), you’ll have to make sure you don’t let your weight slip above 170 pounds.
Look, I do have a little gut, but I’m also pretty big in terms of muscles. Does the BMI take my buffness into account?
The straightforward answer is, no, it doesn’t differentiate between fat and muscle. “Body composition one-on-one: muscle is denser than fat,” writes Lilla Laczo for ShapeScale.com. “This simply means that if you put the same-size portion of muscle and fat next to each other, muscle is going to weigh more. For this reason, it is not logical to assume no difference between muscle and fat when predicting someone’s obesity level.”
To that end, according to a Huffington Post article, the main problem with the BMI is that it doesn’t concern itself with where the fat in your body is stored, which is a more adequate predictor of whether or not you’ll end up dying of diabetes. “This means someone with a high muscle mass, like a rugby player, may be categorized as overweight or obese, when, in fact, they are heavy because they are strong,” reports HuffPo. “On the other hand, elderly people or those who do not exercise regularly may have a low muscle mass, which categorizes them in the healthy weight range despite being overweight.”
Additionally, BMI doesn’t really work as a good predictor of obesity for children and teenagers, elderly people, pregnant women and some non-white races, since they don’t fit into the stock standard measurements. Not to mention the fact that BMI doesn’t even differentiate between a man and a woman’s body.
So why do people even pay attention to BMI?
This answer is going to hurt: “‘Because it’s simple,’ Rexford Ahima, a medical professor at the University of Pennsylvania,” told Live Science. As per their report, “It’s easy to weigh people and measure their height. For most people, BMI provides a ‘reasonable measure’ of body fat, but is not accurate for athletes (who weigh more because of muscle) or older people who have lost height, he said.”
BMI is really meant to be used as a general predictor for the likelihood of a person developing a range of issues linked to excess weight. These include diabetes, arthritis, liver disease, several types of cancer, high blood pressure, high cholesterol and sleep apnea. “In addition, independent of any particular disease, people with high BMIs often report feeling better, both physically and psychologically, once they lose excess weight,” reports Harvard Health.
The other thing that BMI is useful for is measuring the health of a population, rather than an individual, according to Margaret Hays, accredited practicing dietitian and spokesperson for the Dietitians Association of Australia, who told HuffPo in the same article mentioned above that it’s more “useful just for a very quick appraisal.”
So is there a better way for me to judge my own body’s health than using BMI?
Frankly, there’s no good way to judge your own body, but I know what you mean, and yes there is. As per a 2015 study, the body shape index (BSI), “seems to more accurately depict the variability in circulating insulin and lipoproteins than BMI at least in young, healthy male subjects.”
The what now?
The BSI — calculated by measuring your waist circumference and dividing that by your BMI score and your height — has the advantage of addressing the biggest drawback of BMI. “While BMI fails to account for how fat is distributed in your body, Shape Index doesn’t,” reports ShapeScale.com. “It uses WC [waist circumference] in its equation, which is a proxy for abdominal fat distribution. As mentioned earlier, abdominal fat carries several health risks and therefore, is important to consider.”
So yeah, you can claim that your elevated BMI — or even BSI score, for that matter — is due to your muscular physique. But really, deep down, you know that no amount of muscle is going to protect you from dying an early death unless you get rid of that beer belly.
Andrew Fiouzi
Andrew Fiouzi is a staff writer at MEL.
