This worked for me.
I saw a few kids obsessed with sugar, because their parents were total health food nuts and never allowed the kids to have any candy or soda.
What I did was just not have it in the house. If the kids were at a party, they had soda and candy.
If they were eating with me, it wasn't offered to them.
Since it wasn't forbidden, they didn't realize how little they had.
I have to admit, I like candy, so it was more the soda that we did this with. But it would work with candy too.
When they grew up, I asked them if they noticed they hardly ever had soda. They didn't.
If I had forbid it, they would have realized.