I had to look it up but it looks similar to most meal replacement plans like Nutrisystem and Jenny Craig. I did Nutrisystem for a while and frankly, did not travel with my food, just make healthy choices while at WDW. It's pretty easy to do, most TS places have a grilled meat and veggies, you just need to make sure you ask for the veggies without any sauces. The QS places are a little harder, most have a salad as long as you don't load up with dressing, you should be o.k. As far as the walking, while yes, you are walking alot, it's not sustained long periods of heart racing walking so you aren't really burning a whole lot more calories than you do at home. You spend a lot of time standing and waiting and the walking you do isn't usually at a fast pace. I don't count steps, I do work out at home and wear a heart rate monitor. When I go to WDW, I get up every morning and take a fast paced walk (used to jog ruined my knees) around the resort for at least 30 min. That is my exercise, any walking I do in the parks is just every day walking.
