A 20st teenager who was addicted to playing video games has lost half of his body weight in three years to pursue his dream of joining the marines. Jai Harms, 17, from Waterlooville, Hants shed an incredible 10st by ditching a diet of fast food and his games consoles to train five hours a day. His weight had ballooned to a staggering 20st 7lb by his 14th birthday when he feasted on a diet of bacon rolls, snacks and Chinese takeaways every night. At 14 Jai Harms weighed over 20st but just three years later the teenager has lost half of his body weight . Now three years on Jai's waistline has dropped from 46in to 28in and the determined teen is now nine months into a course at the Military Preparation College in Portsmouth, spending half the day on physical training. Jai says that before he decided to turn his life around he had very little respect for his own body existing of greasy takeaways. 'It was pretty bad - I would eat what I want, when I wanted. 'I would make regular trips to McDonald's and order McFlurrys and milkshakes with my meals and my lunch was normally four bacon rolls. 'My dad used to work for a Chinese restaurant too as he delivered food and at the end of the every day we used to get free meals.' As well as a bad diet Jai would be immobile for hours of the day devoting his time to video gaming. Jai slimmed down in order to fulfill his dream of joining the marines and now trains everyday . Before he began his weight loss Jai would spend 12 hours a day playing games on his Xbox . 'When I was in school I barely moved. I would just sit around and play on my Xbox for 12 hours a day, probably more, from the moment I woke up until I went to bed. 'I would play car racing games and FIFA football but I don't even look at the Xbox now.' Jai was bullied over his weight at school but decided to turn his life around on New Year's Eve 2011 when he told his mum Andrea, 48, he wanted to take up boxing. Three months later she and his father Neil, 51, gave him permission to start and Jai started training at his local club once a week. When Jai stepped on a set of scales he discovered his weight had reached an unhealthy 20-and-a-half stone. Jai decided to ditch the computer games when he wanted to take up boxing and is now a champion for his age . Before joining the military college Jai lived off four bacon rolls for his lunch and a Chinese takeaway every night, but now the 17-year-old survives off a high protein diet . Shocked into action Jai soon started running three times a week in addition to his boxing and started to lose between one and two kilos a week. When he enrolled at the Military Preparation College (MPCT) the weight kept dropping off and he has now even been crowned as the Hampshire and Isle of Wight boxing champion for his age group. Jai said: 'I always wanted to look like Floyd Mayweather the boxer - he's my biggest inspiration in life. 'I also watched a lot of TV programmes about people wanting to lose weight, like A Year To Save My Life, and thought "if they can do it, then I can do it". He added that he couldn't have got to where he is today without the help of his loving parents. 'My parents are really supportive and are constantly pushing me - mum has made me healthy lunches and dad has been there training me from the start.' Jai now feasts mainly on pasta and chicken and three protein shakes a day in between his busy schedule of five hours worth of military training and gym work a day. He can now run an impressive 1.5 miles in just eight minutes thanks to his marine training. During a 27-week course at the Military Preparation College, a student will typically run 170 miles, do 9,500 press ups, 9,500 burpees, 9,500 squats and 9,500 sit ups . Jai says that as well as his parents support he has found an equally supportive team at the Military College. 'Everyone is so supportive at the Military Preparation College, so I knew there was no need for me to worry about joining. 'Of course it is challenging at times but we're all one big family and everyone helps each other get to where they want to be. Jai is now using his skills to help others to get fit at the military college . 'In the space of a few months after joining I was at where I wanted to be. Not only has my physical strength and fitness increased massively, but my mental strength, too.' Aside from improving his fitness Jai is also working on his academic skills. 'I am now much more confident, organised and am improving on my maths and English too. 'My friends and family are so proud and they don't stop telling me how well I've done, especially my dad, my military instructors and my boxing coaches.' Jai is also hoping to use what he has learnt to help others in the same position that he was once in. 'All the students here are amazing. 'One lad at the college reminds me a lot of my former self. I work with him in the gym and physical training to help him get where he wants to be.' The next steps for Jai now are completing his MPCT course, and applying to the Royal Marine commando unit. The Military Preparation College is free to attend and open to any 16 to 19-year-olds who want to get fit, boost their self-confidence and prepare themselves for life, including in the armed forces. During a 27-week course, a student will typically run 170 miles, do 9,500 press ups, 9,500 burpees, 9,500 squats and 9,500 sit ups. There are 16 free colleges around the UK, with new students joining on a weekly basis. Nathan Gibbons, Head of Physical Literacy at MPCT, says that he has been extremely impressed with Jai's progress. 'It's amazing to see how Jai has turned his life by getting fit, healthy and motivated. 'He's now one of the fittest learners we have at MPCT Portsmouth and a real inspiration to everyone at the College. 'He is living proof that with the right amount of hard work, determination and support, young people can achieve incredible things.'
At 14 Jai Harms was addicted to his Xbox and weighed in at over 20st . Desperate to become a marine he ditched takeaways and started training . Now he's halved his body weight and become a local boxing champion .