Obese mother-of-five who ate SIX pasties for breakfast loses nine stone and becomes a champion body builder Joanna Rainey, 45, gorged on chocolate but had no idea she was obese By 24, she had five children under six years old, and weighed over 16st A mother-of-five has become a championship bodybuilder after losing nine stone and going from a size 20 to a size 8. Joanna Rainey, 45, went on a diet when a doctor bluntly told her she was obese. Until then she had been completely oblivious how heavy she had become. I looked in the mirror I saw a thin woman. In my heart of hearts I knew I was overweight but thought I looked all right,' she told MailOnline. Then and now: Joanna was comfort eating for years before she lost weight and became a body builder Joanna's weight started to creep up when she had her first child at 18 . By the time she was 24 she had five children under six years old and weighed more than 16st. After a slipped disc following the birth of her youngest child, Joanna's weight continued to rise and she was classified as obese.. Joanna, from Bangor, Northern Ireland, indulged her sweet tooth by comfort eating and enjoying large portions. She said: 'I didn't eat breakfast because I had really bad morning sickness with my first child so I would associate breakfast with feeling sick. So by 11 o clock I would be on to the chocolate bars. It spiralled from there. Joanna has competed in bodybuilding competitions since 2011 after friends suggested she enter I would eat pounds of chocolate every day. It was an addiction. I didn't drink and I didn't smoke, chocolate was my vice. My portion sizes were horrendous according to my GP. I never thought I was eating too much. I was constantly running around after my kids and snacking, so I didn't register what I was eating. My husband loved me when I was fat. Every Saturday morning he went out and bought me six pastries, which I used to eat with a cup of tea in bed. They were my downfall. I knew if I had one I could quite easily eat a dozen. Pictured here at a wedding reception held after her daughter's wedding, Joanna hates looking at old photographs She ruptured two discs after her last son was born while bending over to pick him up. Joanna says: 'The doctor told me it was to do with my weight. I got quite offended, and said "are you saying I'm fat" but I didn't see myself as fat.' The turning point for Joanna came when she had to lose pounds before she could undergo surgery. About five months before the surgery, the doctors told me I was obese. 'I didn't understand. The doctor showed me all these charts and all I could hear was "you're obese" over and over again. It was like somebody had broken a spell, that the thin woman I saw when I looked in the mirror, was now a fat woman looking back. By writing down everything she ate and drink per day, Joanna was able to see how her weight had ballooned This was the wake up call Joanna said she needed. 'I went to the supermarket and filled the trolley full of treats and I came home and sat in front of the TV crying my eyes out, I knew it was time to do something about it,' she says. I knew I had to lose a couple of stone before the operation, but I decided I may as well get down to the weight I wanted to be. My GP told me to write down every single thing I ate and drank for two weeks. That was an eye opener. He told me my portion sizes were unbelievable. For example I would be eating half a pie with four potatoes. At first, Joanna lost a stone through diet alone and then joined Fitness First and met her personal trainer Ryan Robinson, who changed her life. Weight battles: Joanna with her youngest daughter Denyse eleven years ago Hooked on sport: The adrenaline of competing made Joanna keep going back for more Aged 43, Joanna wore a bikini for the first time since she was a teenager Her first goal was to run five kilometres for a charity run in memory of her father, who had recently passed away. She says: "My dad was my best friend. He was always on my case about losing weight, and my biggest regret is that he never got to see me at my best, he would have been so proud. So I did the race for him. Following the buzz of competing and finishing in just 26 minutes, Joanna was hooked on exercise. I pushed myself so hard, that after I ran through the finish line, I fell to my knees. I had this real adrenaline rush and I really liked it, ' she says. A few weeks after that I was talking to some friends at the gym and they suggested I enter a body building competition. I thought they were taking the mickey. Joanna with her personal trainer, Ryan Robinson, who she says has changed her life forever 'I knew I wasn't in shape for a body building competition, but I had seven months to get in shape. The biggest challenge was for me to get up on stage in a bikini. I hadn't worn a bikini since I was 17. In April 2011, when she was 43-years-old, Joanna started competing in bodybuilding competitions winning the World Bodybuilding and Physical Federation championship and then appearing in the Northern Ireland Fitness Model Competition. 'Now I can hold my own among all the younger competitors, maybe the face shows my age, but the body doesn't. I've got a better body now than I had when I was seventeen. People look at photographs of me when I was heavy and they think I have lost about twenty years. I've been out with my daughters and people have thought I was their sister. 'To begin with my husband didn't really like me losing weight, he was jealous, because he thought I would be more attractive to other people. He felt threatened. 'But I do this for myself, I gave my life to my children and I've supported my husband. In my forties I wanted to do something for myself, while I still can. One thing doing the body building competitions has given me is that now I rule food, rather than food ruling me. 'I haven't had a pastry in three and a half years'.