At our house we talk about "grow" foods and "whoa" foods. How grow foods are good for us and whoa foods are only for sometimes.
I love Dr.Sears who said, aim for 90% good food and 10% junk...if you hit 80%/20% you are doing a GREAT job.
We do have desserts pretty much every night, but at least 5 to 6 nights a week they are fruit (strawberries, cantaloupe, blueberries, watermelon, apple sauce, etc.) I put them in small bowls and everyone has to eat a balanced meal to get "dessert". Other nights we might have ice cream (I buy the individual serving sized cups, or mini ice cream sandwiches).
I guess the key is I just don't buy sweets...if they are not in the house we can't eat them. If I do buy them, I put them up/hide them and my DH and I might enjoy some after the kids are in bed.
I don't ever keep sodas in the house and not even when we go out do we offer them as an option. They will have plenty of years to drink their fill of those. And I water down fruit juices about 1/3rd juice to 2/3rds water...juice is just sugar in a glass, with a few vitamins thrown in.
Maybe I am a bit hardcore...but I so want them to be healthy.
Oh, it is their money to spend, but would you allow them to spend it on a tattoo or piercing?? Maybe just allowing them to buy one sweet treat per outing would be a good compromise.
HUGS!!