Lucas' BMI was incorrectly calculated as one that was off the charts for a child.

Content warning: This article references self-harm and eating disorders. Helplines can be found at the bottom of the page.

A now-anorexic boy was incorrectly told by a doctor to lose weight after they miscalculated his BMI, which his parents believe may have contributed to him developing his eating disorder.

His father, Robert, said he was “absolutely disturbed” at what he found when he recently asked for a copy of his son’s medical records.

The Herald previously reported the 14-year-old Wellington teenager Lucas* was repeatedly denied re-admission to Wellington Hospital’s children’s ward because he was not deemed unwell enough, despite his parents saying they could not keep him safe at home.

His mother, Jennifer, described him as a “dangerously” underweight boy who was prone to self-harming.

The parents earlier said they did not know what had brought on Lucas’ eating disorder as he would not open up to them about it. The Herald agreed not to use their surname to protect their son’s privacy.

Lucas’ medical records, which have been released to the family since the Herald’s article, showed he was observed as having a “significantly raised BMI” a year before his eating disorder began to manifest.

In April 2024, Lucas went to the paediatric clinic at Wellington Hospital for allergy testing.

The clinic recorded him as weighing 58.4kg and being 131cm tall, which led to his body mass index (BMI) being miscalculated as 34.

He was actually 151cm at the time, which meant his correct BMI would have been 25.

BMI is a screening tool that uses height and weight measurements to estimate a person’s body size.

It has been widely criticised for being an imperfect tool that cannot accurately calculate a person’s body fat because it does not take into account things like muscle mass.

The World Health Organisation BMI charts for boys ranges from 10 to 32.

For a 12-year-old boy, it shows a BMI of 25 is just over the obesity line.

A BMI of 34 goes off the chart.

The clinic’s records showed Lucas was diagnosed with “high BMI” and told to exercise more and improve his diet, which included reducing sugary foods and drinks.

“Medical professionals should know better than to tell a kid that age they need to lose weight,” Robert said.

He felt doctors should have known Lucas’ height was off just by looking at him.

Lucas’ anorexia emerged a year ago, when he went from refusing to take lunch to school, to skipping dinner, to not eating anything for several days at a time.

In November 2025, his GP clinic sent a referral letter to the Central Regional Eating Disorder Service (CREDS) for a suspected eating disorder.

The GP’s notes said he was “preoccupied with weight and food” and “thinks he is overweight”.

The notes specifically questioned whether the “obesity diagnosis” and subsequent “lifestyle advice” Lucas got from the hospital “might have had an impact on [him]”.

In December, he was admitted to hospital for a fortnight for a medical refeeding treatment, where his condition improved, but he relapsed post-discharge.

“We watched his eating disorder morph from no food intake to food intake but extreme exercise,” Robert said.

Subsequent medical notes from the hospital’s paediatric clinic stated: “Unfortunately during the paediatric outpatient clinic he was counselled on eating more healthily and needing to lose weight due to this incorrect calculation.”

“It would appear his BMI was actually 25 at this time”.

Health New Zealand declines to comment on BMI blunder

Health New Zealand did not respond to the Herald’s questions about Lucas’ BMI being miscalculated, or the potential impacts this had on him.

In a statement, it said: “Health New Zealand will reach out to [Lucas’] family to discuss any outstanding concerns if they wish.

“We acknowledge the significant stress that eating disorders place on young people and their families throughout treatment and recovery.”

In June, Lucas was taken to hospital after his second fainting episode.

Doctors found self-harm marks on his body which led to him being admitted for four days under a mental health hold.

Since then, a multi-service plan had been created to help Lucas, according to Robert.

He said Lucas’ eating and mood had “dramatically improved” and he was no longer isolating himself in his room.

Robert said it was hard to articulate how he and Jennifer felt after reading the notes and concluding the health system they trusted to help Lucas with his anorexia may also have been part of the cause of it.

“We are angry and upset, we don’t want this to happen to other families.”

*To maintain the family’s privacy, the name of the teenage boy has been changed and the family’s last name has been omitted.

Janhavi Gosavi is a Wellington-based journalist for the New Zealand Herald who covers news in the capital.

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Parents believe now-anorexic child’s obesity misdiagnosis triggered eating disorder