Another one here who has lost weight during my Disney vacations in the past! In addition to choosing healthy foods while away from the resort room, since we fly, we always Fed-Ex a package to the resort about 5 days out, with lots of healthy snacks to save $$. (we also include diapers, wipes, etc. to save on luggage room)
Here's a link for all the menus at the parks and resorts at WDW, including dietary info for special needs, such as celiac disease, etc.
http://allears.net/din/dining.htm
A water hint: All of the restaurants will give you a free cup of ice water if you ask for a "cup" of water. If you ask for "water" they will sell you a $2.50 one. If you do buy bottled water, the bottles can be refilled at water fountains all over the parks and resorts, but you may want to take some of the individual Crystal Light packs for flavor since the water has a bit of an "off" taste.