A 10-year-old boy who is constantly hungry due to a rare condition eats rolls of toilet paper if he is unable to get any other food.

Caden Benjamin, from Standerton in South Africa, weighs 14 stone 2lbs (90 kilogrammes) because of his constant overeating.

He has been diagnosed with a genetic disorder called Prader-Willi syndrome, which is characterised by an obsessive compulsion to eat.

Caden Benjamin, from Standerton in South Africa, weighs 14 stone 2lbs (90 kilogrammes) because of his constant overeating and breathes through a tube inserted in his windpipe

His mother Zola Benjamin says it means Caden will eat anything he can get his hands on.

'At one point, Caden was eating toilet paper. He'd eat rolls of it,' she said.

'Actually, he'd eat any paper he would find in the house. If there's nothing for him to eat, he'll scrape together the dirt he finds on the floor and eat that.'

Several years ago, he was forced to undergo a tracheotomy and he now breathes through a tube inserted into his windpipe.

Prader-Willi syndrome is a rare, incurable disorder that affects thousands of people worldwide, resulting in physical, mental and behavioural problems.

The condition is made worse by the fact that people need less food than their peers because their bodies have less muscle and tend to burn fewer calories.

Caden has been diagnosed with a rare genetic disorder called Prader-Willi syndrome, which is characterised by an obsessive compulsion to eat

His mother Zola Benjamin(pictured) says it means Caden will eat anything that he can get his hands on

Ms Benjamin added: 'At three years old he was 40 kg (6 stone 4 lbs) and at that time, we didn't know what was wrong with him.

'We went to a number of doctors and no one could tell us what was wrong and why he was gaining so much weight.'

CRUEL CONDITION THAT AFFECTS THOUSANDS OF KIDS Prader-Willi Syndrome is a rare disorder which causes the person with the condition to always need food. It affects one in 15,000 children and is caused by abnormalities on chromosome 15. The syndrome is defined by an insatiable hunger and other symptoms such as low muscle tone and developmental delays. Other symptoms include a high pain threshold, speech difficulties and poor temperature regulation. Source: Prader-Willi Foundation Australia Advertisement

Eventually, a doctor at the Steve Biko Academic Hospital in Pretoria ran further tests and diagnosed Caden's illness.

Ms Benjamin said: 'Normally he would start off the day by eating four slices of cheese toast and then an hour later he would drink Coke and eat leftover food from the night before.

'Then at lunch he'd eat two large pieces of chicken. He'd eat hourly for the rest of the day.'

But with his weight spiralling out of control and his health being seriously jeopardised, doctors have put Caden - who wears men's XL size clothes - on a diet.

Ms Benjamin has had to lock all her kitchen cabinets and her fridge and hide all food items in the house.

'He's really battling. I feel so terrible... but the doctors said that if I want to see my son alive, then he has to go on a diet,' she said.

'Each and every day is a battle. I have to check up on him all day and night.'

Caden struggles to move around and even breathe because he is so overweight.

Caden, from South Africa, struggles to move around and even breathe because he is so overweight

He also suffers bouts of depression because he is unable to live like a normal child.

'Sometimes he'll just break down in tears and tells me he wants to go and play with the other children outside,' said Ms Benjamin.

'But he is unable to do that and there's no way I can help him.'