How did Jackie Kennedy stay slim?

Answer 1

She liked to exercise, practiced Yoga and certainly watched her diet. But I believe she was the kind of people who don´t put on weight because I have seen pictures if her since she was a little girl, a teen, adult and she was always thin she only put some weight and looked a little chubby when she was pregnant.

Answer 2

She once quipped to her sister that she should take up smoking to stay thin. She also had a diet that consisted of fish and vegetables later in life.