Atkins will help you lose weight fast.
While Atkins may help you lose weight fast, it's not something that most people can stay on long term. An overall healthy diet that centers on veggies, lean protein, low/no fat dairy and eliminates sugar and processed foods, including sugar, white bread, pasta etc is something you can maintain. It's not fast, but fast isn't healthy and will only result in further gain down the road.
Check out the book "17 Day Diet". It works in three phases of 17 days and the first phase is designed to drop weight quickly and build enthusiasm. My husband and I lost quite a bit of weight on it. You can unlimited amounts of numerous veggies, chicken breast and white fish and salmon. You don't get hungry when you can eat all the chicken and veggies you want! It's not difficult either. I lost 15 lbs in one month and my husband lost nearly 30.