Good luck, I use stone instead of kg. I used to weigh 17 stone, I'm now 10st 5lbs. Cardio is good but you need to add in weight lifting even if you don't want to gain muscle. I currently do 5 spin classes (2 is enough but I want to start road cycling in the summer) a week and 30-45 minutes of weights 5 days a week, 2 days rest. I also get a new diet plan from my personal trainer every few weeks which is great because if I did one myself, I know I wouldn't stick to it.