A three-year-old boy in Palmerston North, a city in New Zealand, has been detected with a rare and recently-categorised eating condition known as avoidant/restrictive food intake disorder.

Luca Dalzell is said to have never eaten a full meal in his life. The doctors at Starship children's hospital told the child's mother, Annie, when he was first diagnosed at the age of two that Luca's case was at an "extreme level".

According to doctors, people who have this disorder tend to lack interest in food and avoid it. It can even result in them having to be tube-fed, the Stuff news website reported.

Annie said her son's condition is due to a sensory processing disorder, which is also known as sensory integration dysfunction. This disorder exists when multi-sensory integration is not adequately processed in order to provide appropriate responses to the demands of the environment.

The disorder meant that when Luca broke his arm earlier in two places, he didn't react.

"His brain wasn't connecting that it was really painful because he was focusing on something else," the mother explained.

Annie added that in some other situations, like standing outside in the wind, Luca might feel as if he's standing in a wind tunnel.

The toddler developed a "debilitating fear" of food which lead to trauma when he was younger.

"When Luca was first offered food, it was just so overwhelming for him, his body rejected it. Anything that went into his mouth or touched his lips would cause him to gag or vomit. Anything he did allow in, he would get really, really sick from it," the mother-of-three said.

Annie revealed that she had never heard about this disorder before having Luca as her two other children did not have it.

The mother also added that there is a lack of awareness about this disorder and it was not just about fussy eating or a behavioural problem, but a serious, debilitating condition. She wanted to share her son's story in order to raise awareness about the condition.

"He's never had a meal in his life but he will have a taste of bits and pieces."

Luca occasionally sips on pureed fruit and vegetables. He also has a bite of crunchy foods, such as muesli bars and chips, sometimes.

"More often than not, it causes him to gag or vomit to quite an extreme effect, which is really sad to see when he's trying to overcome his fear."

Luca has spent most of his time at Starship hospital, including at its feeding clinic. Now at home, Annie runs two therapy sessions a day for her son.