I lost 15kg after high school (still overweight tho
).. but I haven't gained any of it back so I guess thats OK
I was going to the gym about 4 times a week or once every other day, and the only real change I made in my diet was for lunch every day I'd have a big bowl of salad with a can of tuna!
At the gym I'd do 30 minutes on the treadmill and another 30 minutes on weights or machines.
If you're just starting out I recommend just eating a little bit less every meal, and exercising maybe once or twice a week. It took me about 4 months to lose the weight I did, but I can tell you that I did not have a great time during that period and that may deter people from doing it at all.
I've wanted to do it again but I keep putting it off.. uni and stuff have made me put it off for 3 years!