I am obese and looking to do a complete makeover on my fitness level. I need to lose 120 lbs. I would like to do this asap. I also want it to be permanent so how much should i realistically expect to lose a week and how do i know what to do to accomplish this goal?

Looking to start my exercises tomorrow morning. Will be doing weekly weigh-ins on Saturdays effective immediately. Graduation is in June and Swim suit season begins in June as well. In June we are going on a trip to Arkansas my goal weight for June 6 is to lose 50 lbs putting me at a weight of 185. Just a tad over 3 lbs a week. I intend to be down to a size 12/14 from my current size of 18/20. I plan to drink 6-8 8oz glasses of water per day, exercise 1 hour per day and journal each day. I also plan to start calculating my sugar and cream usage in each cup of coffee.