talking to your kids

I have a tentative surgery date and want to talk to my kids - daughter is 6 1/2 and son will be 4 in August. My question to all of you is how to talk to my children about this surgery. Don't know how to approach them - especially my daughter who is very smart and tall and skinny and is already aware of fat and skinny. We all eat very good - my kids eat a ton of things most kids won't touch.... so the eating healthy will not be a change. But portions will and the funky food the first 6 weeks will be different.

any help from those of you who have had the surgery and have small children I would appreciate it.

Thank you,

Helena