18 years old has not reached the point of losing weight. You can lose weight by exercising more, eating reasonably and adjusting your diet structure ~ ~
There are many kinds of sports. If you can, climb more mountains and run every day. You can often go shopping if you like. Ps: Don't eat while shopping. Drink mineral water when you are thirsty. There is no upper limit for shopping for no more than 3 hours at a time (basically, I don't think it is necessary, and every girl has to go shopping for more than 5 hours).