Hi Blondie! I'm 19 as well and have 50kgs to lose
I'm definitely looking at losing all of this in a year - so that by my 21st birthday I'll be hawt
I have tried optislim shakes, but I wouldn't really recommend them because you pretty much put all the weight on as soon as you stop. I'd suggest definitely just start off with 20 - 30 minute walks a few times a week, and eating healthy - tracking your intake through calorieking.com.au. I've finally come to the realisation that there is no 'easy' way to lose weight, it's a long and difficult journey, but with the right people to talk to (like us here!) it can be made easier and more fun!
Keep up the motivation hun