Weight and Kids

So I'm attempting to more or less reinvent the wheel on my family's relationship w/ food/eating/diet/body image so that I can hopefully avoid giving Caleb all the issues in these areas that I have. To this end I have joined Weight Watchers and am attempting to learn how to eat so that I can lose weight and set a positive example b/c "Do as I say and not as I do" has never yet been proven to be an effective parenting technique.

And my family has issues with food. The gross majority of my family members (at least my immediate family) are over weight according to the Body Mass Index (BMI) which is a generally accepted government sponsored guideline for what is a "healthy weight". So I'm voting our relationship and methods of teaching food, diet and body image etc are not good and we need NEW methods.

And the message I WANT to teach my kids is that you're beautiful regardless of how big or small you are. You still have worth no matter how you look. I don't want their self esteem to be based on their clothing size.

That said I want them to be healthy and being obese is not healthy. There are no fat old people. There are fat people that look old but they're not actually any where near as old as they look. The fat makes them look older and they die younger and I don't want that for me or my family.

So given societies issues with food, body image, weight etc that my kids will undoubtedly pick up on - how do I talk to and teach my kids about weight and eating and what is and is not healthy and how to encourage good diet and exercise with out backhanding their self esteem? Because I don't know how. I know all the wrong ways to do it (or at least all the methods I'm aware of are examples of the wrong way to say things).

I'm learning w/ my poor husband that I don't know how to say this right (God bless him for being a forgiving soul when I put my foot in my mouth and prove I'm related to certain family members) and I really want to learn this skill before Caleb gets older and I mess with his head.

Ideas? Recommendations?

Is there a good way or has that research not been done yet?