Weight training at least three times a week is essential to healthy weight gain. This will aid in gaining and maintaining lean muscle mass. To continue gaining lean body mass, a person will need to vary and develop their workouts by increasing either the weight they lift or the number of reps or sets. Compound movements are one way in which a person can build muscle effectively. These include weight lifts that involve multiple muscle groups, such as deadlifts, squats, and bench presses.