My nearly 4yo DD1 seems to be obsessed with sweet or sugary foods.
We eat healthily at home with the occasional toddler-appropriate treats like not too sugary gingerbread-man biscuits or rice cakes or raisins.
But whenever we go to a friend's house where she knows they have biscuits (custard creme type) she asks for biscuits (multiple) as soon as we get through the door.
If we are out at a playgroup and there are biscuits available at snack time I have to watch her like a hawk- she'd eat a whole plate if I turned my back.
Other children like biscuits and sweet things but they seem able to take one or two. I know that DD1 would not stop eating until she was sick or the source ran out.
We went to a party yesterday and there were plates of cakes, biscuits, sweeties, more cakes and more biscuits and yet more and more all laid out for the 3 and 4 yo children to reach. Other kids had one, maybe two, sweet things and then played and had to be encouraged to eat more later on. My DD1 made a bee line and picked up several items then ate as quickly as she could then grabbed more as I turned my back to get her a drink. I said "no more" but again she grabbed another item (6 sweet cake things within 10 mins of us arriving) in spite of us having had a good lunch an hour previously.
It put me in mind of a drug addict demanding a fix 
.
I took her to the bathroom where she was wild-eyed and fidgety and explained that she had definitely had more than enough and that if she took anything without my permission we would go home. Soon after she slumped in my arms- almost comatose and I watched as all the other kids played.
My DD1 is usually well-mannered and gregarious. She's enthusiastic and playful- if occasionally shy. She adores her pre-school and her friends and loves her regular activities (swimming and dancing) and generally plays well with her sister and friends. She's normally a joy.
But put her in a room with sugary stuff she becomes jumpy and divisive and I can almost see her working out how to get more and more. As I said previously it's like addicts behaviour.
I notice a marked difference between DD1's behaviour and DD2 (DD2 likes sweet stuff- will take an item if offered, even two if she can, but will stop.)
Has any one else got experience of this type of food behaviour and how to deal with it? Is there a difference in the way different people handle sugar? Am I just a bad parent who has failed to educate her daughter to just take one? Why do the other kids seem able to handle being in a room with these foods without going into tailspin? Does anyone else dread a party where sweet junk food is laid out all over from the onset? Should I try to see a paediatric dietician?
These are the questions keeping me awake at 2am.