When she was married to Roger Vadim (he directed her in Barbarella) and she was very young, a teenager I think, he was very critical of everything about her body. If you've seen Barbarella, she's in a skin-tight catsuit for the whole movie, so any imperfection would be hard to hide (esp. in those old days without CGI). And of course her whole childhood was spent among actors, notoriously shallow and absorbed in their looks, so she really never had a chance.
My attitude toward her should be more pity and compassion, I know, but she really did lie over and over about how she would never have plastic surgery and that she maintained her perfect body through exercise and diet. So many flabby women in the 70s believed her and subsequently wondered what was wrong with them, that they couldn't achieve the same results. It was kind of a mind-fuck on Jane's part. She helped perpetuate her own low self-esteem through the thousands of women whose self-esteem she damaged.
I think Lily Tomlin is gorgeous. I think Jane Fonda looks plastic and a little ridiculous for her age--Cher is the same way. I adore her, and she was beautiful--still is, if she'd let herself be--but the mask that her face has become is a little frightening.
For the record, I'm 71 and I treasure my many wrinkles and age spots and even my saggy body. It's all evidence of the fun I've had living my life and I would never want to lose my souvenirs.