How do I participate in Facebook Groups/Pages and keep my participation private from my contacts?

[.]

Okay here's the deal...

I want to join a weight loss group and become more active in some political groups I like without my comments going to the news feed for all of my friends and family to see.

Is this possible? I realize that it's public information but is there a way to keep certain people from reading every comment I post on Groups/Pages?

Thanks.

[SAI]

to participate and comment u'll first hav to like that page.
to like tat page click on tat page and then u see that like button on top of the title of the page
u click like and then u can start commenting
for it 2 be secret u'll hav to go 2 ur profile and click edit my profile
then u'll find an option visible to everyone ,only friends and bla bla bla
so click the option u want and there u go
it wont be visible to much of people