Let's Do Lunch Community

I just bought your book a few days ago and went to buy all the items I thought i would need to start the program. After two trips I think I have most everything I'll need to start. I have 2 questions for you. (1) Is your plan set up for those meals plans only? Or can I substitute one meal for another. example: If on day 2 I made the dinner meal as specified and then ate the leftovers for the lunch meal the next day instead of the specified lunch meal for the 3rd day, is that ok as long as I don't switch a lunch for a dinner meal. There are only 2 of us and I will end up with lots of leftovers if I dont use them in my mealplans the rest of the week.
(2) When I eat some of those meals, I cannot eat the salad that is supposed to accompany it. Must I eat everything that is on that particular meal plan?

When you say not to eat unless you are hungry it brings to mind several other diets that I have been on over the past 4 years that says, if you dont eat, your metabolism will slow down and you wont burn as much off. Even my doctor says we should eat a little something every 3 hours just so our body doesnt go into starvation mode. Is it OK to eat a piece of fruit every 3 hours just to keep your body from thinking you are starving?

Thanks
Deb