Is It Possible To Save 70% At The Grocery Store Just By Couponing?

I have several friends that are trying really hard to become extreme couponers and I keep telling them that I think the show is staged or that coupons will take over your life if you figure out how to make money at the grocery store. Although, it is very possible that I am just unwilling to work hard enough at collecting coupons just to save some money. You tell me! Is It Possible To Save 70% At The Grocery Store Just By Couponing?