How to gain mass in a short period of time

When I saw my younger brother at the airport last Sunday, I barely recognised him. I had not seen him for ten months. When he was leaving for Sydney, he looked like a typical skinny guy. Now, after several months, his posture has changed, he has a wonderful tan, and what is the most surprising, he looks much more muscular. I have been asking him how he managed to gain mass in such a short period of time. He says he decided to start an exercise plan ten months ago. He went to the gym three times a week and lifted heavy weights. He increased the number of reps little by little. In the meantime, he changed his died completely. He started eating food high in protein and carbohydrates. He also quit eating junk food, stopped smoking and drinking alcohol. He started taking some supplements for bodybuilders: creatine, omega-3 fatty acids, vitamin-B complex and calcium. I don"t know why he decided to gain mass and change his lifestyle so drastically. I mean, it"s a good thing that he doesn"t smoke or drink alcohol any more. I"m just curious what prompted him to give it up. Maybe he was trying to impress somebody? Perhaps he got to know a girl and wanted to look more attractive? Well, I won"t ask him. At least not now. Perhaps he will tell us soon.