Redd Rocket's Pizza port in Tomorrowland is great.
They have a variety of fresh made salads (I like the chicken ceasar one), pasta dishes, and pizza. If you get veggie or cheese pizza, and split a slice with someone, that's pretty healthy. The pizza is not greasy at all. They also have some basic pasta/marinara dishes which could be considered healthy as well.
I agree with Bengal BBQ.
River Belle Terrace re-opened recently and they have some good looking salads and fresh sandwiches (tri tip, turkey, and pulled pork).
The Main Street Bakery sells sandwiches as well as fruit.
There is fruit everywhere, as mentioned.
Healthy food is MUCH easier to come by at DLR than at WDW...