Imagine if your child thought normal food would kill them? Imagine if they had never eaten a hot meal in their life, or had chocolate for every meal, or would only drink bottles of milk?

My Child Won't Eat follows the controversial work of leading child psychologist Dr Gillian Harris who believes that there's a special category of extreme food refusers who aren't just being fussy, but who have a food phobia which needs to be properly treated.

The film meets some of Dr Harris' young patients who are terrified of putting food in their mouths, and follows their family's emotional journey as Dr Harris applies her pioneering techniques to help the children face up to the things they fear the most.

12-year-old Rachel from Bolton eats chocolate for every meal. Breakfast is 15 squares of cooking chocolate and 10 chocolate fingers. Lunch is similar, and her evening meal is a 'hot' meal of Rice Krispies mixed with melted cooking chocolate.

After years of struggle, Rachel's parents have stopped offering her new food. Mum Gill recalls how Rachel didn't grow out of her fussy toddler stage:

"I felt like a failure in the early stages because it didn't matter what we tried. We tried all the strategies like making it into a funny face, a flower and a pattern. All the little things and really none of them worked."

Rachel has started to feel self conscious about her eating habits and her restrictive diet is making it hard for her to lead a normal life.

"I don't just choose to eat that kind of stuff," says Rachel. "It's not because I'm being awkward. Whenever I try any food I always get scared."

After searching for more than ten years for someone to help, Rachel and her parents begin work with Dr Harris from the Feeding Clinic at Birmingham's Children's Hospital to help overcome Rachel's extreme food phobia.

Dr Harris believes it's important people realise such children aren't just fussy: "If I got a sheep's eye and I put it in your sandwich and squidged it down nicely and said 'eat this, this is a nice sandwich,' you probably wouldn't be able to put it in your mouth and this is what children have to what seems to other people to be quite normal foods.

"Parents are isolated. The normal rules of eating don't apply. Whatever they try, whatever strategies other health professionals suggest, don't work for these children."

Dr Harris also believes that at least one child in every school has food phobia but they are falling through the net because they're not correctly diagnosed.

The Feeding Clinic's three golden rules for helping children overcome their restricted eating all fly in the face of what parents are told everywhere else about how to bring up their children healthily.

Firstly, parents must not stress about their fussy child having a balanced diet. If a child only wants to eat junk food, let them eat it.

Secondly, don't try to hide food, disguise it or play games with food as it'll make the child with rigid eating patterns even less likely to eat it. "Once you're into making carrots into funny shapes you've lost the plot," maintains Dr Harris.

Thirdly, don't force fussy children to try a new food: wait until they want to try it themselves. Prompt and encourage them to try, but never force them.