If you are an adult male who currently weighs 91 kg (about 200 lbs), is about 180cm (5ft 11in) tall and your goal weight is 80kg (about 176 lbs), this will be your numbers:
If you can therefore cut your daily calorie intake to about 2,400 calories a day, making sure you eat as healthy as possible not to cut on your nutritional intake (virtually impossible without supplementing) and maintaining your daily protein intake to keep and build healthy muscle mass, you will start losing weight and keep on losing weight until you reach your goal weight, where it will stabilize.