Sarah says after carrying on elaborate lies to friends and family for eight years, she is ready to start telling the truth.

TELL DR. PHIL YOUR STORY: Know someone with outrageous behavior?

“I seriously came here to get to the bottom of why I can’t stop lying to people,” she tells Dr. Phil on Thursday’s episode.

However, Dr. Phil says Sarah's behavior may reveal otherwise. “When people lie, there’s what we call leakage,” he explains to Sarah. “There’s something called duping delight. It’s where people will lie, and they can’t control all of their body, and micro-expressions in their face and all, while they’re controlling their words.”

WATCH: Woman Claims Former Friend Who Repeatedly Lied To Her Became Obsessed With Her

He shows Sarah clips of her interview where she’s confessing to her lies, but her behavior doesn’t match her words – and why he says it’s duping delight. Watch in the video above.

On Thursday’s episode, see what happens when a former friend of Sarah’s who is a cancer survivor confronts her about her behavior. Check here to see where you can watch.

TELL DR. PHIL YOUR STORY: Do you need Dr. Phil to "get real" with someone?



Cancer Survivor Confronts Former Friend Who Lied About Having Cancer: 'You Are A Parasitic Psychopath'