A father who blogs about lifestyle has been sentenced to eight years in jail for causing the death of his newborn son by insisting that the child survive only on sunlight instead of food and milk.

Maxim Lyutyi, 44, and his partner Oxana Mironova, 34, neglected to properly feed their baby Cosmos, who died from 'pneumonia and emaciation' before he was even a month old.

The Russian father will serve his sentence in a high-security penal colony.

He would take the baby away from his mother for entire days, even 'dousing him with cold water to harden him', as reported by Mash news outlet.

'The little body could not withstand the abuse: exhaustion developed and breathing problems appeared. But even in this condition, the child was not shown to doctors.'

Lyutyi caused 'intentional infliction of grievous bodily harm' to Cosmos by insisting the baby be nourished mainly on sunlight, the court in Sochi heard.

He admitted his guilt in a court appearance last week after previously trying to blame Mironova, who has already received a non-custodial sentence of two years 'correctional labour'.

Lyutyi told the court he was guilty of 'negligence'. 'I admit my guilt,' he said. 'If I knew that my son was born prematurely, that his mother had contraindications for pregnancy, then at the first symptoms of the child's illness.

'I would immediately contact a hospital, regardless of the wishes and beliefs of the mother…'

He urged would-be partners to care for their health before conception and pay more attention to the baby than he had done.

On video, he said: 'Your Honour, distinguished court, I still insist [I did not deliberately kill my child…].

'This is purely a crime of negligence…without such intent. I emphasise once again that I loved my son, cared for him.'

Lyutyi had been held in custody for a year where he was found to be eating meat - pasta with stew - ignoring his own philosophy.

The court was earlier told Lyutyi wanted to raise the newborn on prana-eating - a diet in which people go without food and water for a long time and 'feed on the sun'.

He was accused of barring Mironova from breastfeeding the child, and was described as a 'radical raw food fanatic'.

'He wanted to experiment on the child, feed him purely with the sun, and then advertise it to others that this is how you can eat,' said one source.

A court official said Lyutyi was also fined £860.