A dietician says New Zealand should dump a children's health check tool that can lead to preschoolers being labelled fat and unhealthy when they might not be.

Pegasus Health dietician Lucy Carey criticised the effectiveness of the weight-height Body Mass Index (BMI) test in a New Zealand Medical Journal article published today.

The test is used by health professionals during the Ministry of Health's Before School Checks (B4SC).

The test uses a person's weight and height to calculate their structure.


It gives a number that will determine whether they are underweight, average, overweight or obese.

According to the formula, a handful of the All Blacks are obese and the rest are overweight.

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Carey says many parents expressed concern saying their child was classed as fat and unhealthy despite eating healthily and exercising daily.

Carey, who receives referrals from the B4SC of 4-year-olds who have identified as being overweight or obese, told the Herald the test was "seriously flawed" and needed to be overhauled.

However, the Ministry says it's an effective tool for early detection and has signalled it won't be getting rid of it any time soon.

Lucy Carey, Registered Dietitian, Pegasus Health, Christchurch. Photo / Supplied
Lucy Carey, Registered Dietitian, Pegasus Health, Christchurch. Photo / Supplied

But Carey said it was a bizarre measure. As a result of the test: "Short people think they are thinner than they are, and tall people think they are fatter.

"What worries me is families who may really want support don't get it because their child has been categorised as being a healthy weight and some families don't actually need the referral but they think they do," Carey said.


Wellington mum Kym Clough said her daughter Abby, now 7, was told by a Plunket nurse she was fat at the age of 4 and, three years on, the comment has stuck.

"She'll finish a two-hour tap class and say 'Mummy do you think I've lost weight?'

"As a parent it's awful knowing she is constantly thinking about her body image like that," Clough told the Herald.

The mum-of-two said she remembers coming home after the B4SC and crying thinking she was a bad mother.

"I was horrified because she eats healthy, we grow our own vegetables and are not the type of family who sit in front of the TV for ages.

"The next day I took my daughter to kindy and asked the kindy teachers if they thought she was fat, because I knew they would be honest, and they said absolutely not."

Clough said hearing the nurse tell her daughter she was fat came as a huge shock because she was always an active kid.

"Even from a young age we would go to the park and she wouldn't walk, she'd run and my brother would always say she's going to be a gymnast or a long-distance runner."

Abby Clough, 7, was told she was overweight by a Plunket nurse despite eating healthy and being an active kid. Photo / Supplied
Abby Clough, 7, was told she was overweight by a Plunket nurse despite eating healthy and being an active kid. Photo / Supplied

She said when she got the referral to see a dietician to talk about healthy eating she was angry.

"I thought that she thought we were unhealthy people, which just isn't true. Abby is the type of kid who will eat broccoli raw but it felt like we were being judged based on one stupid test."

Carey, who lives in Canterbury, said the system should be scrapped.

"Instead, we should be taking a universal approach where every family, regardless of the size of their child, could have a conversation with the health professional about healthy living."

Auckland paediatrician Maneesh Deva agreed there were limitations and harms to voicing a child's BMI.

"A holistic, family-centred approach would be a good step forward for New Zealand," Deva said.

Plunket's clinical services manager of the B4 School Checks, Sophie Woodger, said the BMI testing was being discussed with the Ministry as part of the Well Child review. "The conversation around BMI is around nutrition and growth monitoring; it's all about balance.

"It's about having a healthy active lifestyle, eating a varied diet and spending time playing and growing. This will all form part of any growth assessment at any age."

Woodger said it was not acceptable for staff to be telling a child they are fat.

"Our staff receive extensive training on how to have difficult conversations with whānau in a sensitive and respectful manner.

"We would like to apologise to this mother and encourage her to make contact with us to progress her complaint."

Ministry of Health deputy director of public health Harriette Carr said BMI was one of the leading risk factors for poor health outcomes in New Zealand and using it in the B4SCs enabled early identification of children who may need extra support to achieve a healthy weight.

"Although the BMI screening tool is not a perfect measure, it helps to identify children who may benefit from further assessment or support with respect to their growth and weight.

"It is the most widely used, practical and convenient measure of growth, and is recommended in guidelines internationally."