I actually had to do a project similar to yours.
To encourage healthy eating in schools, make what the kids like.
For example;; People like pizza in my school a lot.
We just used whole grain crust, lower soduim sauce, low-fat cheese & made sure there was lots of veggies on it.
People liked bell peppers/olives/tomatoes and all that, so we offered it. Tasted just the same as normal pizza.
And if you want to encourage fruits, just ask the schools to offer smoothies? o.O Like, if you offer breakfast in the mornings?
Like just use strawberries/bananas/oranges, and then put in like carrot juice or some other vegtable juice. Can't even taste the vegtables,really. They don't need to know there was carrots in it.
Part of it is to also make the food look more appealing. If it honestly looks like a grey blob, would you eat it?
or even something drenched in oil is not too good for you either. Baking foods with a little oil (Olive/Canola) makes it crispy and lower in bad fats.
looks good=people will generally try it.
and keep it a low price point. If you can get something for $1.50 and less healthy vs 3.00, less appealing but more healthy, people will go for the first one.
not so low it can't make profit though. Fresh food may be a bit more expensive, but what would you pay for health?
Not sure if this is what you meant, but I did do a project on this in 9th Grade, and the school board liked it.
PM me if you need more clarfication.