Right I've probably missed the boat here but this is the best advice you will get in this thread, and it's tough love so be warned
Bollocks to any of these "I only eat yoghurt and nothing else all day" flash-diets. Here's a general rule of thumb, if you go for the drastic all off at once diets you will eventually put the pounds back on. It's really, really, easy eat sensibly. Don't have chips every single fucking night of the week, I have a decent dinner and a nice tea with some fruit here or there. If you can't eat like a normal person and have a pudding every single night then guess what that's why you're overweight and unless you are willing to change what goes through your mouth then you WILL NOT lose weight because that's why you're fat to begin with, you eat too much.
Secondly, if you still live with your ma or you're with a bird then take over the cooking, or at least your own cooking. Use the bbc site, I'm guessing you eat a shitload of ready meals and take aways. Fuck that shit. Cut out anything you haven't made for yourself, use lean meats (chicken and mince) and you will eat better tasting meals than any of the "Tesco Special" shit you've been paying £5 a night for. Just follow instructions and £3 can get you 2 portions of a lovely meal better than any of that TV dinner shite.
Cut out Coke and any soft drinks, look at the bottle, 1 Lucozade has about 60% f your daily sugar and it does fuck all for you. Drink water.
In short: stop eating shit like crisps chocolate in between meals. Cook for yourself and that doesn't mean heating up ready meals. Stop drinking soft drinks.
You're not on a diet, you're changing you're whole eating lifestyle, if you don't you'll put it back on when you go back to eating shite.
Join a gym.
Bollocks to anybody who says you don't need to, that running in the street is alright. Join the fucking gym and tell EVERYONE, that way you'll have the pressure to get your arse there.
Go on the treadmill, every single day, people will say it's too much you'll get bored - fuck them treadmill is boss and the pounds will fly off, get a decent music player and you're set. Do other stuff in the gym if you want, it's fun but get your arse on that treadmill.
It's really simple, eat less and exercise more.
Remember ANYBODY can lose weight and the only person that can do it is YOU, believe in yourself when others choose not to.