As far as numbers go, this one carries a lot of weight.
Doctors, healthcare providers, and personal trainers emphasize body mass index (BMI) for a myriad of reasons, from personal weight loss aspirations to insurance premiums. Think you’re fit, fat, overweight, or obese? Find out with a simple number, a number it turns out is based on a equation developed in 1832: a person’s weight divided by the square of his height.
But for all its metaphorical and literal weight, the BMI might not really actually mean much. According to a recent article in Mother Jones, it in fact might be a “big fat scam.”
“A higher BMI doesn't necessarily mean you're less healthy,” the article says. “In fact, patients with heart disease and metabolic disorders whose BMIs classify them as overweight or mildly obese survive longer than their normal and underweight peers.”
A slew of studies show how poor the BMI is at indicating health, yet it’s the number that determines prescriptions, premiums, political policy, and the percentage of Americans who are overweight and obese.
Apparently those percentages don’t mean a whole lot. From Mother Jones:
"In 1998, the National Institutes of Health lowered the overweight threshold from 27.8 to 25—branding roughly 29 million Americans as fat overnight—to match international guidelines. But critics noted that those guidelines were drafted in part by the International Obesity Task Force, whose two principal funders were companies making weight loss drugs.”
So, what is a good indicator of health and mortality? Fitness. “It's much more important to avoid low fitness than it is to avoid fatness," Carl Lavie, a cardiologist and author, told Mother Jones.
The lesson learned: don’t sweat your BMI. Go out and actually sweat.