Obesity metrics must go beyond BMI - experts

Healthcare experts are backing a worldwide rethink on how obesity is diagnosed, calling for an individualised approach.

The global Commission on Clinical Obesity has recommended using other methods to diagnose obesity and not relying on the Body Mass Index (BMI).

University of Auckland Public Health Professor Sir Collin Tukuitonga says the clarification will help reduce stigma and improve patient management.

"The new guidelines will improve care for people with obesity by better differentiation on obesity categories – pre-clinical obesity which is minimal health risk and clinical obesity which has significant risk complications.

"Several studies have shown that Polynesian people have more muscle mass than fat and cut off points have been adjusted to take account of this reality.”

The Commission has recommended two categories of obesity diagnosis to distinguish between obesity causing chronic disease and obesity associated with variable health risk, but not ongoing illness.

Massey University professor of Māori Health and Nutrition Lisa Te Morenga says the tweaked approach will help towards more individualised treatment.

“The focus on obesity as a disease as opposed to a lifestyle choice is well overdue and will contribute to reducing the weight stigma experienced by people with obesity, particularly Māori and Pacific peoples.

“Some groups in our population, notably people of Asian and Indian descent, can carry a small amount of excess fat in high-risk places around the vital organs while presenting with a relatively low BMI, and therefore their increased risk of conditions such as diabetes could be missed.”

The UK are seeing success following their sugar tax among other policies - should NZ follow suit? Photo/Unsplash

University of Otago Professor Sir Jim Mann says BMI on its own is not enough to assess a person’s health risk and other health indicators must be considered such as where fat is stored on the body.

“If they've got red blood sugar, if they may have a tendency towards diabetes, or indeed diabetes itself, if they've got high levels of blood fat, cholesterol and triglyceride, because that's also going to influence how you approach the person with a high BMI.”

Mann said some sportspeople may have high BMI due to having more muscle, but this is the exception.

“Let’s face it, the majority of us, whether we are Pacific, whether we are palagi, Pakeha, whatever you want to call us, we are not athletes, so the BMI is not actually a bad index.”

He says while everyone is unique, the continuum of other health risks tends to increase with body fat.

Sir Collin Tukuitonga joins Pacific Mornings to discuss the biggest issues facing Pacific island nations.

“Some people with a BMI of 40 who have got normal cholesterol, normal blood pressure, normal blood glucose, because they've got the genetic predisposition not to get that way, but to a very large extent, they are consequences of obesity.”

Calls for prevention measures

Mann urged the Government to invest in preventative measures such as cardiovascular risk screening for diabetes from age 35 for Pacific and Māori communities.

“Our health budget is so restrictive in this country … You can actually prevent people with pre-diabetes going on to get diabetes by giving them advice and giving them extra care about changing their diets, changing their lifestyle.

“I don't want people with what they're calling pre-obesity to lose out, I don't want prevention to lose out.”