That was "Angie", on ABC in, like, '81 and '82. She was this waitress who married a doctor (played by the male lead from the AIRPLANE movies) and had an overweight sister with "man problems." It was a hit sitcom when I was 11 or 12, I think. The overweight sister went on to become some sort of bodybuilder/HOT girl, and I don't remember her being in much after that...good eye, guys! ((My old lady spotted her immediately--"That's John Travolta's little stalker girlfriend from SATURDAY NIGHT FEVER, isn't it?"))