"Why are kids so obsessed with candy and ice cream?"
The simplest answer is that sweets are associted with the sugar in breastmilk, and kids are programmed to love breastmilk.
"How can you have your pudding if you don't eat your meat!"
Sugary snack have little nutritional value and we mainly eat them just for pleasure. So make sure they get their nutrients in first before filling up on junk.
I don't like the idea of eating just for pleaure, as this leads to eating when youre not really hungry, which leads to being overweight.
I also don't like using food as a reward for the same reason. That being said, I have worked miricales with difficult kids just by promising them a Jolly Rancher. However, I do this infrequently and never as a regular practice. (See: "Bribery").
What about the "Sugar Rush?"
If you think your kid goes out of control after they have sugar...it's NOT the sugar. Kids don't need an excuse to have high energy...it's just how they come. There is no sugar rush.
"So...Is sugar bad?"
Believe it or not, sugar does not cause any real bad health effects. It does not directly cause diabetes or weight gain, or even cavities...not directly. Although sugar has been demonized, it can be eaten in normal amounts without any real negative effects.
like everything else, provide sweets in moderation. Kids should not be complety denied the pleasre of an ice cream on a hot day, birthday cake, and the occasional candy, as long as it does not replace real food.