The Venerable BMI Quotient Called Into Question

"The BMIs [body mass index] do get fairly high, but our complications remain reasonable. I don't think it's a reason to turn people away [from knee joint replacement]."

"All the cartilage is completely gone [with end-stage degenerated joints]. Even a lay person looking at this joint [with the eroded bone, inflammation, red tissue, scar tissue] if it was open would say, 'Wow, that looks painful." 

"...Unless you've had this [degenerative joint disease] or seen people like this, you can't even imagine."

"Obviously if you're putting more load through that joint, it gets worn and torn sooner."

Dr.Harman Chaudhry, orthopedic surgeon, Sunnybrook Holland Orthopedic and Arthritic Centre

"The best marker of adiposity will have the strongest association with mortality."

"We need to shift the way we're thinking about fat away from sheer quantity toward distribution, which seems more physiologically relevant."

Guillaume Pare, professor of pathology and molecular medicine, McMaster University

"[It's not often the case that people accumulate fat in one place and not the other; either the hips or the waist.] The two go together."

"The simple message should be not to accumulate too much fat, wherever it goes."

Keith Frayn, emeritus professor of human metabolism, University of Oxford

When it comes to health, one measurement doesn't tell the whole story.iStock (2); Everyday Health

The ratio of weight to height has been used by doctors, insurance companies, statisticians and the World Health Organization for a half century as a guide in assessing overweight and obesity. Its viability as a tool to fully comprehend overweight and obese people's health score is now coming under scrutiny, with some health professionals damning it as inaccurate and misleading, recommending it is past time to put it to rest and use an alternate measurement scale.

Some argue that the BMI was formulated as a measurement of weightedness based on white males of European descent, making it an inappropriate tool as a generalized system for other racial and ethnic groups. Its use to arbitrarily disqualify heavier physiques from joint replacement, along with other life-altering 'elective' surgeries is increasingly being questioned. 

 

 

"BMI has now become the organizing principle of a massively sprawling surveillance system and the default tool in society's arsenal in the 'war on obesity'", two Harvard academics wrote in MedPage Today. "And the consequences are dangerous", they concluded. Missed diagnoses occurring when doctors inadvertently assume the person's complaints or symptoms are merely a reflection of weight and the indiscriminate recording of an individual's BMI which can be totally irrelevant.

The BMI measurement of acquired fat fails to account for bone or muscle or frame size, while overestimating a fat condition. Nor does it consider the deposition of where the fat is located. Where it is now well known that belly fat is more harmful than fat accumulated around hips, Waist-to-hip ratio, according to a McMaster University professor, is superior to and should replace the BMI.

A massive meta-analysis involving over ten million people enrolled in a total of 239 studies across four continents --Asia, Australia and New Zealand, Europe and North America -- found overweight and obesity defined by the BMI associated with higher rates of death from any cause, including coronary heart disease, stroke and cancer in each global region studied; results published in the Lancet.

Critics point out that one size does not fit all; the BMI does not represent an optimal measurement of adiposity (fat); the formula in their opinion is scientifically illogical "There is no physiological reason to square a person's height" argued British mathematician Keith Devlin. The waist is crucially ignored in the formula at a time when it is cautioned that visceral fat that wraps about internal abdominal organs is particularly unhealthy, raising the risk of Type 2 diabetes and heart disease.

Waist to hip ratio (WHR) is now promoted as a more reliable prediction of an early death. An analysis by Dr. Guillaume Pare and former student Irfan Khan was produced an abstract at a European diabetes conference finding waist-hip ratio more reliably predicts early death than BMI. Mortality risk, they found, was lowest for those with the lowest WHR, rising steadily with increasing WHR.

Waist circumference divided by hip circumference, according to the World Health Organization, means a healthy WHR is 0,.9 or lower for men, 0.85 of less for women. A 2015 study of 40,000 Americans found nearly half classed as overweight according to their BMI, with 29 percent classed as obese and 15 percent with severe obesity were cardio-metabolically healthy; risk of diabetes and heart disease low, based on markers such as cholesterol, blood glucose and blood pressure. Over 30 percent of normal weight subjects were metabolically unhealthy.

Two of the world's largest groups of bariatric surgeons published new guidelines recently, the first in 30 years, calling for expanding eligibility for weight loss surgery to reconfigure the gut and digestive system controlling how many calories people can consume at any given time, and absorb. New standards are less restrictive, yet based still on BMI rather than factors such as fatty liver disease or high cholesterol.

Complex surgery is required in replacing knees and hips in people with severe obesity where potential complications require a risk-benefit discussion. People are unable to straighten their legs, bend their knees, experience trouble in and out of cars; pain disturbs their sleep leaving them depressed and with mood changes from lack of sleep. Surgery can make the difference between a normal life and being in a wheelchair. Yet patients are turned down for surgery, dismissed with a recommendation that they lose weight to qualify for surgery.

BMI range	Classification	Risk of poor health
less than 18.5	underweight	high
18.5–24.9	normal weight	low
25.0–29.9	overweight	low to moderate
30.0–34.9	obese class I (moderately obese)	high
35.0–39.9	obese class II (severely obese)	very high
40 or greater	obese class III (extremely obese)	extremely high