The Global Commission on Clinical Obesity proposed 18 criteria for diagnosing clinical obesity. (Pixabay: jarmoluk)
In short:
Health experts have proposed new guidelines for defining obesity.
Two new categories have been suggested — clinical obesity and pre-clinical obesity.
What's next?
The new definitions aim to resolve any conflict in medical circles over whether obesity is a disease or just a risk factor.
Global health leaders have proposed a “dramatic overhaul” of the way doctors look at obesity, publishing new guidelines that split the definition into two distinct categories — clinical obesity and pre-clinical obesity.
The proposed changes, announced today, have been five years in the making and aim to reframe obesity by moving beyond Body Mass Index (BMI) calculations.
What are the key takeaways?
The authors determined that "clinical obesity" existed when organ function was reduced by weight gain and "pre-clinical obesity" when patients were healthy but carrying excess weight.
Rather than just BMI, the authors from Global Commission on Clinical Obesity proposed 18 criteria for diagnosing clinical obesity, taking into account a range of problems from sleep apnoea to liver disease.
Could this new formula replace the BMI?
Photo shows A doctor measures a patient's waist in her office.
Patients with clinical obesity might have symptoms that include breathlessness because of the impact of weight on their heart and lungs, knee or hip pain and reduced motion, metabolic problems and dysfunction in other organs.
In these cases patients may require interventions — whether it's weight loss surgery, medications or other help.
Patients with pre-clinical obesity would only need monitoring and risk reduction measures.
The recommendations from the Global Commission on Clinical Obesity also move away from BMI and its weight-to-height calculations in favour of waist-to-hip ratios and other measures of belly fat.
Former World Obesity Federation chair Professor Louise Baur, from the University of Sydney, was one of the commissioners and said the new guidelines "acknowledge the nuanced reality" of obesity.
Obesity exists on a spectrum
The new definitions, published in The Lancet Diabetes and Endocrinology, aim to resolve conflict in medical circles over whether obesity was a disease or just a risk factor.
Commission chair Professor Francesco Rubino, of King's College London, said obesity existed on a spectrum with some people having excess fat but being otherwise healthy and others having serious related health impacts.
The Body Mass Index has been used by health professionals to recommend weight loss for some individuals. (iStockPhoto/Sergey Ivanov)
"We cannot afford to not treat clinical obesity but [we also] cannot afford over diagnosis of obesity," he said.
The commission says BMI could still be useful as a screening tool but should be used in combination with either waist measurements, waist-to-hip ratios, waist-to-height ratios or body fat scans.
"We don't want to throw out BMI but we want it to be used in a thoughtful way," Dr Baur said.
The ABC has previously reported cases of patients being turned away from essential surgeries based on BMI cut-offs.
'BMI is outdated'
Willow Moscarda has welcomed the change after her GP refused to give her a referral for breast reduction surgery, saying her BMI was too high and she simply needed to lose 10 kilograms.
The Perth woman was just 20 and already an 8JJ cup size when she asked for help.
Willow Moscarda said the Body Mass Index was out of date. (Supplied)
"She didn't even look at my breasts that are incredibly disproportionate to my body or listen to my personal struggle with body image," she said.
"They're obviously just following set protocols. It's not about weight, it's about distribution."
When Ms Moscarda eventually got another doctor to refer her, the surgeon ultimately removed 2kg of tissue from her breasts, she estimated her bust weighed 5kg overall.
"I wasn't overweight, I had large breasts. BMI is so outdated I can't believe it's still used today."
Andrew Wilson is the advocacy lead for the Weight Issues Network, Australia's peak body for lived experience of obesity.
He said the BMI had its place as a "simplistic" and "easy metric" but was not enough.
He said people like himself, who were living with obesity or who were overweight, felt shamed and stigmatised by the health system when their measurements were the sole focus rather than a patient's overall health.
Mr Wilson said introducing a diagnosis of pre-clinical obesity was a positive move designed to prevent future health issues, rather than "lumping everyone into the one cohort" of obesity.
How does this affect GPs and other health workers?
Dr Terri-Lynne South is a GP, dietitian and chair of Royal Australian College of General Practitioners Specific Interests Obesity. (Supplied: Dean Canton)
Monash University Associate Professor Priya Sumithran, who co-authored the findings, said it gave them "a way to distinguish people for whom obesity is a risk factor for future health conditions, and for those whose risk has already materialised".
"It allows clinicians to distinguish between a person whose health needs to improve … or apart from having excess weight, is relatively healthy," she added.
"I think there's widespread support already for the criteria and intention. On the other hand, implementing things into practice always requires resources and it's not straightforward to enact."
The non-medical origins of the BMI
Photo shows Two feet on a red tartan scales.
Terri-Lynne South, the chair of the Royal Australian College of GP's specific interest obesity management group, supports a move away from BMI as a sole diagnostic tool.
"It was never meant for that. The more we understand the chronic, complex condition, the more we realise that we need to not be defining it by BMI alone," she said.
Dr South said the proposed classification system should allow doctors to break down some of the stigma of discussing obesity with their patients, while giving them the time to treat their condition.
"It's not just a black and white diagnosis based on a single measurement, it's complicated. So, I actually think that this is a real opportunity to allow better education at the patient level and the practitioner level about something that is nuanced."
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