America has a weight problem, or do they? Estimates seem to vary but according to the National Institutes of Health (NIH) nearly one-third of Americans (30.7%) are overweight, while 42.4% are obese. Nearly one-in-ten (9.2%) are severely obese. The corresponding figures for kids are a little over half the rate for adults but still significant.
There are a variety of viewpoints about what causes America’s Battle of the Bulge. You can blame it on genes, sedentary lifestyles, snacking between meals, prepackaged calorie-dense foods, fast foods and cheap foods, all which arguably contribute to obesity. It’s probably all the above. One thing that is unlikely to contribute to excess weight: the Body Mass Index (BMI).
The measure BMI has been controversial for years. One criticism I’ve often heard was that a muscle-bound weightlifter would be obese based on the BMI. The following is from the New York Times:
“Based on B.M.I., Arnold Schwarzenegger when he was a bodybuilder would have been categorized as obese and needing to lose weight,” said Dr. Wajahat Mehal, director of the Metabolic Health and Weight Loss Program at Yale University.“But as soon as you measured his waist, you’d see, ‘Oh, it’s 32 inches.’”
What is BMI and why use it as an indicator of weight? It’s a health metric designed to encapsulate weight, height and other measures into one number.
The body mass index, or B.M.I., is a ratio of height to weight that has long been used as a medical screening tool. It is one of the most widely used health metrics but also one of the most reviled, because it is used to label people overweight, obese or extremely obese.
The BMI index has a lot of detractors.
Nearly half of people deemed overweight, as defined by having a B.M.I. between 25 and 29.9, and nearly one third of those said to be obese — a B.M.I. of 30 or above — were actually in good metabolic health.Advocates for overweight individuals and people of color note that the formula was developed nearly 200 years ago and based exclusively on data from men, most of them white, and that it was never intended for medical screening.
Some public health advocates want to replace BMI with a roundness index.
So welcome a new metric: the body roundness index. B.R.I. is just what it sounds like — a measure of how round or circlelike you are, using a formula that takes into account height and waist, but not weight.It’s a formula that may provide a better estimate of central obesity and abdominal fat, which are closely linked to an increased risk of developing Type 2 diabetes, hypertension and heart disease, unlike fat stored on the buttocks and thighs.
Whether the BMI should be replaced with BRI depends on the purpose of the measure. If the index is to predict mortality from a weight-related health problem, then a more predictive measure is beneficial. If the index is to convince patients to lose weight by pointing to a chart it’s probably less useful. Perhaps I’m naïve but probably most overweight people realize they’re overweight but may not realize how it boosts their chances for illness and disease. Maybe pointing to a chart or to their circumference would motivate them to lose weight but it’s unlikely. In any case, the argument is academic for most people. Whether the measure of obesity is called BMI or BRI is ignoring the elephant in the room, so to speak.
New York Times: Time to Say Goodbye to the B.M.I.?