I personally can't handle corn syrup, soft drinks are the worst, even the "natural" ones if they have high fructose corn syrup. It changes my personality, and not in a good way!
I need to eat protein and my two teen boys do, too. I keep all-natural, uncured hot dogs, cold cuts and chicken nuggets around for them to snack on. No preservatives or dyes. The fewer weird ingredients, the less you have to worry about.
I cook in bulk and so there are leftovers to snack on. For example, I'll bake 2 tri tips and slice them thin, or cook up a couple pounds of ground turkey. The leftovers can go in the fridge or freezer and be heated up with some refried beans and cheese on a tortilla.
For fruit, my boys will eat it if when it's prepped and ready to eat. So I scoop melon balls, slice apples or wash and set the grapes out for lunch. If it's there and ready, they will eat it. If they have to wash, peel or cut the fruit, it sits uneaten in the fridge. Oh well.... My boys also will also eat fruit if it's in a smoothie. I buy the large bags of frozen strawberries, raspberries and blueberries and blend them with a banana and some yogurt.
Vegies are a little more difficult but we eat them every day. I've noticed they take the minimum amount when I cook frozen vegies, but the last time I saute'd fresh baby spinach it all got eaten up. So this summer I'll be experimenting more when the farmers market comes to town.