text: whats a good diet to do in order to loose 15 pounds in a 4 month span and keep the weight off. reasonable!!!!!   15 lbs in 4 months is a very good pace. . . thats only about 3 or four lbs a month.  basically you will need to eat about 500 calories less per day than what you need.  so lets say you are 180 lbs, and want to be 165.  you probably want to eat about 1800-1900 calories a day to maintain that weight.  so you want to eat about 1600-1700 day to lose weight gracefully.  3500 calories=1 lbs.  adn to lose 15 lbs in four months, you should try to lose about 1 lb. a week!  good luck!