It is possible to lose fat and gain muscle at the same time

One study from California State University tracked a group of healthy men for eight weeks. The men ate a lot of food--over 4000 calories a day--and did weight training four days a week for 60-90 minutes. The men gained an average of six pounds of muscle, but also gained ½ pound of fat. In another study, men also trained with weights several times a week, but this time, they ate just a little over 2000 calories a day. This group gained 2.5 pounds of muscle and lost over 7 pounds of fat.