Piper, who mentors victims of acid attacks through the Katie Piper Foundation, recounted two stories when she had faced discrimination because of the way she looked.
In one incident, some men in a van whistled at her when they saw her from behind but then threw a sandwich at her when they saw her face (she was wearing a plastic mask at the time following some treatment).
Another time, a first date walked out on her in a London restaurant leaving her to pick up a tab that was more than £700.
Despite such experiences, Piper said: "You need to realise, on the whole, people are really good. Seventeen years ago, when I did that first cutting edge documentary (Channel 4's Katie: My Beautiful Face), what it did is it opened me up to the good side of society. Up until that point, I had seen true evil in mankind, but only in two people (her attackers)."
She said if she had to give one message to her younger self, it would be: "If you've ever felt less than... you've hated yourself or felt ashamed, it was never you. It was society, consumerism and capitalism. It was beneficial to someone, somewhere, to hold you down.
"Whether that was in a relationship, a corporate company or a brand, it was never you. You were always fine just as you are, and you always will be."