Emily Hughes, from Smethwick, lost three stone and 5.5 pounds, landing a spot in the final 30 of Slimming World's Young Slimmer of the Year 2017 competition.
The competition is out of all the 16 to 21-year-olds who attend Slimming World's 16,000 groups across the UK and Ireland.
Emily joined the Oldbury Slimming World group to feel more comfortable with her size.
She said: “I think a lot of young people struggle with their confidence from time to time and I was no different. My weight meant that I was becoming more and more self-conscious though, and it was starting to affect me in lots of different ways – to the point where I’d make excuses not to do activities with my friends because I felt uncomfortable all the time.
“I’m not going to lie, I was quite nervous about the thought of joining Slimming World at first because I thought that people might judge me for being overweight at such a young age.
"I definitely shouldn’t have worried though. Everyone at my group is really lovely and they’ve all been so supportive of me.
“My friends and family are really proud of what I’ve achieved – and I’m feeling quite proud of myself too actually.
"Eating more healthily has made me think about how active I am as well, so I’ve taken up netball and enjoy long family walks."
She added: “I can still have burgers, chips, curries and chocolate – I just have to make some healthy swaps, like switching white bread for wholemeal and using lean mince. Understanding my relationship with food has been a real eye opener.
“I feel as though I’ll be able to keep up this healthy way of life forever – which is something I never thought I would say! My confidence has grown loads too, which is great.”
Sam, a current Olympic gold medallist and defender for both England and Great Britain’s hockey teams, was blown away by Emily’s transformation.
She said: “Health and fitness is a huge part of my life, so I understand how difficult it can be sometimes to make sensible choices. The way that Emily has turned her life around is nothing short of remarkable and although we’ve only just met – I can’t help but feel a little proud of what she has achieved.
"It just goes to show that if you set your mind to it, anything is possible."
Lorraine Banner, who runs the Oldbury Slimming World group which Emily attends, said: “I’m so proud of Emily. What she’s achieved is so much more than just losing weight.
"I’ve watched Emily transform into a strong and confident person who has the world at her feet."
Anyone who wants to lose weight – whatever their age – is welcome to pop along to the Oldbury slimming group at The Salvation Army Community Church and can call Lorraine on 07434728698.