Leading health professionals are redefining obesity as BMIs are thrown out

Farwell inaccurate BMIs

Health experts are recommending rethinking the way obesity is defined and treated, calling for BMI calculations to be left in the past. GPs are backing the move, saying a new approach could break down stigma. 

The accuracy of Body Mass Index (BMI) in diagnosing obesity has been doubted for some time now.

The height and weight calculations fail to consider people's overall health – we all know someone who despite being relatively healthy, has been told they’re obese because their short stature, big boobs or muscle density boosts their BMI over 30. 

Now health experts are recommending redefining obesity and approaches to treating it, leaving BMI calculators in the past.

Looking at obesity as a spectrum

In a report published in The Lancet Diabetes & Endocrinology journal, authors from the Global Commission on Clinical Obesity insisted health professionals need to take the overall health of patients carrying excess weight into consideration and avoid overdiagnosing obesity. 

Many countries define obesity as having a BMI of 30 or more, but the Commission said more factors need to be taken into account when diagnosing and treating obesity than just height and weight.

Professor Francesco Rubino from King's College London chaired the group. He said “Obesity is a spectrum”, as “some have it and manage to live a normal life, function normally”, while “others can't walk well or breathe well, or are wheelchair bound with significant health issues."

The authors insist new definitions would help ensure more accurate diagnosis accounting for these differing symptoms.

Many countries define obesity as having a BMI of 30 or more, but the Commission said more factors need to be taken into account when diagnosing and treating obesity than just height and weight. Image: Unsplash

Clinical obesity

People with chronic illnesses as a result of their weight would be diagnosed with ‘clinical obesity’ in line with the recommendations. 

Those with clinical obesity could experience difficulty breathing, knee or hip pain, metabolic issues or reduced motion, with treatment options including medications or weight loss surgery.

Pre-clinical obesity

Those who are relatively healthy, but at risk of developing obesity in future due to excess weight, however, would be diagnosed with ‘pre-clinical obesity’ as per the recommendations, and receive different treatment to those with clinical obesity.

These patients only need to focus on risk reduction and monitoring.

Monash University Associate Professor Priya Sumithran co-authored the report, she said this approach to defining the disease “allows clinicians to distinguish between a person whose health needs to improve … or apart from having excess weight, is relatively healthy”.

She said this approach to defining the disease “allows clinicians to distinguish between a person whose health needs to improve … or apart from having excess weight, is relatively healthy”. Image: iStock.

Pairing BMIs with other tools

While BMIs aren’t necessarily great for accurately diagnosing obesity, the authors said they may still have a place in testing.

The measurements neglect to consider things like muscle and fat when determining patients' health. But the Commission said BMIs can be a useful screening tool for obesity, if they are paired with waist-to-hip ratios and other measurements like body fat scans when diagnosing patients. 

Rubino said “We cannot afford to not treat clinical obesity but [we also] cannot afford over-diagnosis of obesity”

Chair of the Royal Australian College of GPs, Terri-Lynne South thinks the recommended changes could help to reduce stigma and encourage more personalised treatment. She said “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."

Originally published as Leading health professionals are redefining obesity as BMIs are thrown out