The Geordie Shore star, 22, confessed that, despite her bravado on the show, she wasn't as confident as she made out, thanks to being bullied.
Speaking to Closer this week, Holly said: "During school I would agonise and dissect everything the bullies would say to me and I'd be glum."
Confessing to resorting to self harming, she added: "I'm ashamed to say it, but I only stopped cutting myself when I was 16, when I was happier within myself."
KATIE HOPKINS SLAMS 'FAT' MARIAH CAREY: "EAT LESS, MOVE MORE"
And Holly said the only thing behind her incredible transformation is hard work and eating healthily.
She said: "It took me a year to lose the weight and there's no secret to it – I ate less, cut down on fatty food and started moving more. I ate healthily 80 per cent of the time and had treats at the weekend."
Along with her new found confidence, Holly has been enjoying a new romance with Geordie Shore co-star Kylie Christie, 21.
Holly admitted the pair have been growing closer, but said she doesn't want to put a label on things just yet.
Read Holly's full interview and see her amazing photo shoot in this week's Closer Magazine, out now.