Ben Green, 10, has a rare condition that means he is ravenously hungry all the time.
It means his parents, Paul Green and Angela Booth, have to keep their son under permanent surveillance in case he binges to a dangerous level.
However denying strong-willed Ben has led to exhausting tantrums that can last for hours.
Angela said: ‘Left unattended, he would eat absolutely anything. His compulsion takes over every other emotion.
‘We have to say no and that’s when the crying starts. He can go on and on for ages. He sobs in my arms. It’s horrendous. I have to be as strong as I can because I know I have to help him.’
Ben has to stick to a strict calorie-controlled diet to keep his condition – Prader-Willi syndrome (PWS) – under control.
PWS is caused by an abnormality to chromosome 15 – a genetic accident that cannot be predicted. It affects just one in 22,000 people.
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The condition stops Ben’s brain from realising that his stomach is full. His parents have been told by medical experts that unless his eating is monitored and controlled he would become so overweight it could kill him.
Paul, 56, said: ‘He was three weeks premature and at first we thought that might be why he was quiet but then our anxieties grew. We weren’t new parents. We knew something was wrong.
‘Initially, babies with PWS are so weak and find it difficult to feed. Then they start to grow up and began to develop a voracious appetite.
‘Now we have to watch Ben constantly. He’ll open cupboards, looking for food. At a friend’s house I spotted him eyeing up the bowl of cat food on the floor. I think he’d probably tried a bit before I managed to get him away.
‘If he sees anyone with food or drink, he will use his considerable charm to wheedle something out of people.
‘When we’re in the supermarket, he will find the kindest looking member of staff on…