WARNING: This story contains details that some readers may find distressing.

A father on trial for allegedly starving his severely malnourished daughter says he "adamantly disagreed" with medical advice she was at risk of a heart attack and rejected test results.

The man, and his wife, are in the midst of being tried in court for starving their teenager who was described by doctors as being "dangerously underweight".

On his second day giving evidence, the man was asked about a visit to a doctor in April 2021, when the girl was aged 17 and weighed not much more than 27 kilograms.

In that visit with Dr Amy Murdoch, the father said he was shocked to be told his daughter was "very underweight".

"I didn't think I felt the same way," he told the court.

Dr Murdoch told him she was liaising with the child protection department, and there was a discussion about the impact of his daughter's condition on her heart.

The father said his daughter, who was vegan, soon started eating eggs although she "wasn't too keen on it".

But even though he'd accepted she was "a bit underweight", he didn't have concerns, he told the court.

"I felt she was healthy," he said.

At a follow up appointment shortly after, Dr Murdoch told the father his daughter was "dangerously underweight".

Still, the father said, he had no concerns about his daughter's health.

Father refuses feeding tube request

His lawyer Oliver Paxman asked what he thought of suggestions she could have a heart attack, and the father, who worked in cybersecurity, said he "adamantly disagreed".

He said his own analysis of the blood test results were that the "markers for re-feeding syndrome weren't there" and there was no need to admit her to hospital.

But a child protection worker then called the family to discuss being taken to Perth Children's Hospital the very next day.

The father said he believed this was only for more testing, and not for admission.

He said his daughter was "horrified" at the prospect of going into hospital.

Eventually he agreed to her admission, he said, "for testing and safety ... just to make sure everything was going okay for her".

But when advised that his daughter would require a feeding tube, he refused.

He said he didn't give consent because his daughter "was eating, could eat", and "didn't need a tube".

It was at that point the government took over the girl's guardianship.

Man admits controlling home

The father was asked a series of questions by his wife's lawyer, Michael Perrella.

He admitted to having access to his wife's phone, lying about who was calling and deleting text messages without her knowledge.

He also admitted to being verbally abusive to his wife, who sat in the dock weeping during the evidence.

The father told the court he had been in control of the household's finances, had access to the mother's finances, and dictated how the family was run.

He admitted to shielding the mother from concerns about their daughter's health, including those expressed by dance teachers.

He said his wife was "horrified" at the child protection department's involvement in their daughter's care.

Following Mr Perrella's questions, the prosecutor asked the father if he had a medical degree and he said he did not.

Weight guess wrong

Earlier, the father said he'd provided an estimate of his daughter’s weight to the department without actually weighing her.

In an email sent to the Department of Communities in late 2020, he claimed his daughter was 149 centimetres tall and weighed 43 kilograms, with a body mass index of 19.

It was about five months later when the daughter was found to be just over 27 kilograms.

On Wednesday, the father rejected claims she was dangerously unhealthy with childlike interests, saying was a fussy eater who watched adult shows like Married At First Sight.

The trial continues.