The 38-year-old reality TV star has told fans they can keep their skin looking youthful by resisting the temptation to smile whilst posing for a photograph.
Asked how she avoids getting wrinkles, Kim - who has kids North, five, Saint, three, and 12-month-old Chicago - told fans at an event in Los Angeles: "Don't Smile."
Kim - who is married to rap star Kanye West - also admitted that her first pregnancy and the reaction to her weight gain prompted a change in her attitude.
She explained: "It changed my mood; it changed who I was; it changed my personality a lot. It changed the way I viewed wanting my picture taken.
"After I had the baby, I was like, these are the same people that made fun of me ... I didn't want to smile for them."