I am glad you are motivated to lose weight. Let me assure you if you start your healthy weight loss diet journey at young age of 18 you will be able to get fantastic result due to naturally high metabolism rate. All you need to do is balance your three major meal in terms of essential nutrients and have filling snack. Also, plan a daily work out schedule starting with Lift weights 3times per week rest days you can go for 30 mins brisk walk.