The athletes who came to see Dr. Philip Maffetone were undoubtedly fit. They were able to run long distances. They could lift tremendous amounts of weight.
Yet they were in less than optimal health. They complained of fatigue and poor performance. They exhibited signs of burgeoning cardiovascular problems, including high cholesterol and high blood pressure. None could be mistaken for being overweight. But they were, as Maffetone describes them, "a little chunky around the waist."
After measuring their body composition using a special contraption that weighed them underwater, Maffetone confirmed the underlying cause of their health issues: "I realized that, yeah, their [body fat percentages] were pretty high, even though they were normal weight."
In other words, he says, they were "overfat."
Maffetone, an Arizona-based independent researcher and clinician who has worked with many elite athletes over the past 40 years, is among a group of health experts now pushing for a change in how we measure, describe and think about unhealthy body composition. Rather than focus on weight and size, they say, a much better indicator of people's health is how much fat they have.
In two separate papers published this year in the journal Frontiers in Public Health, Maffetone and his colleagues argue that body mass index (BMI), the conventional measure of whether people are "overweight" or "obese," is flawed and needs replacing. They suggest using other measures, such as waist-to-height ratio, to determine, instead, who is "overfat."
BMI, a person's weight divided by their height squared (kg/m2), has long been considered an imperfect measure of health. The formula was first described by 19th-century Belgian scientist Adolphe Quetelet, who was interested in measurements of "l'homme moyen," or the average man. It was reintroduced and popularized by American physiologist Ancel Keys more than a century later.
In spite of its widespread use, many experts agree BMI merely reflects a person's size, not his or her body composition. So even though the World Health Organization defines adults as "overweight" if they have a BMI of 25 or higher, and "obese" if their BMI is 30 or higher, a heavy but lean athlete who has lots of muscle may be erroneously categorized as obese.
Conversely, and perhaps more commonly, an individual of "normal" weight but with dangerous amounts of visceral fat – the kind that surrounds the internal organs and is linked with all kinds of serious health problems – can have a BMI below the obese or overweight thresholds. This is often the case with people of certain ethnic backgrounds, such as South Asians and East Asians, whose BMIs may be considered normal, but who have large amounts of visceral fat that put them at higher risk of Type 2 diabetes and heart disease.
(This is why Maffetone says he prefers to call people "overfat." It's not to insult them, he says; it's the excess fat they carry around their middles that makes people sick, not weight itself. And using accurate terminology, he believes, can help them better understand their situation.)
Because BMI does not capture individuals who are normal weight but are considered metabolically obese, existing overweight and obesity rates underestimate the number of people who have body fat levels that impair their health, Maffetone says. In their second paper, published this summer, he and his colleagues estimated up to about 90 per cent of adult males in some of the most developed countries in the world were overfat. Among Canadians, they estimated 84.5 per cent of men and 68.5 per cent of women were overfat.
By comparison, overweight and obesity rates in the country are considerably lower. More than 61 per cent of adults were overweight or obese in 2015, according to Statistics Canada data released this summer, based on BMI.
As the Canadian Medical Association Journal reported last month, this discrepancy has renewed the debate about how best to measure obesity.
Maffetone says one of the most accurate ways of determining whether someone is overfat is by using dual X-ray absorptiometry, also known as DXA, a special scanning system typically used for measuring bone mineral density.
(DXA has since replaced the underwater weighing method Maffetone used on his athlete patients earlier in his career.)
But since DXA isn't practical or accessible for everyday use, he suggests a simpler measure is waist-to-height ratio. That is, you take the circumference around your belly button and divide it by your height.
While there is no consensus on what is a "normal" level body fat, Maffetone says researchers often consider men who have more than 17.6 per cent body fat and women who have more than 31.6 per cent body fat to have excess body fat. If using waist-to-height ratio, he says, a value of more than 0.5 translates to a risk of being overfat.
"Basically, our waist should be less than half our height," he says.
Dr. David Lau, an obesity expert and professor of medicine at the University of Calgary who is not involved in Maffetone's research, says that, in spite of the limitations of BMI, experts do not yet have a better replacement.
"Right now, we're still struggling with that," he says. "Because unless we can identify how much extra body fat a person has, it's very difficult to quantify on an individual basis whether the extra body fat [they have] is causing health issues."
Lau says proposed alternatives, such as waist-to-height ratio and neck circumference, have not been validated by epidemiological studies. "So the most robust scientific or medical data to support the definition of obesity remains BMI," he says. He notes the 2006 Canadian clinical practice guidelines he helped author recommend measuring BMI as well as waist circumference.
While there's plenty of debate around the merits of various measurements, Dr. Arya Sharma, professor of medicine and chair in obesity research and management at the University of Alberta, says determining which one is best comes down to what it's being used for – whether it's for research purposes, to determine population prevalence or for routine clinical practice.
"If you want to know if people in Canada are getting bigger, BMI is fine," he says, but when it comes to caring for individual patients, it takes a whole clinical assessment to determine one's health.
If all of this leaves you wondering how to interpret your own body measurements, Lau sums it up this way: "The bottom line is: the leaner we are, the healthier we are. And of course, the more physically fit [we are], the better off we are when it comes to over all health."
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Is BVI the new BMI?
Body mass index (BMI) is widely regarded an imperfect measure of obesity. Could body volume indicator (BVI) provide better results?
BVI is a new measure of body composition and weight and fat distribution introduced earlier this year by BVI America LLC, a company collaborating with Mayo Clinic researchers.
Given as a value between 1 and 20, BVI is calculated as a ratio between total body volume and abdominal volume, its developer Richard Barnes explained in an e-mail.
It is computed using a special tablet application called BVI Pro App, which analyzes a patient's digital photos. A health-care professional takes a full-body photo of the patient from the front, as well as one from the side, and the app provides several measurements, including their waist-to-hip ratio, total body fat percentage, amount of visceral fat and BVI. A BVI value between 0 and 10 is considered to be in the average or healthy range, while a value above that indicates greater health risks, Barnes said.
While he described BVI as a more accurate indicator of individual health risk, don't expect to say goodbye to BMI any time soon.
"BVI is not designed or intended to be a replacement for BMI, but an add or 'added value' measurement," he said.