A good barbell program will work wonders. I'm doing Starting Strength, and it's amazing - strength gains every single workout. Extremely empowering to feel like you can move heavy things! You'll need to eat more though, or you'll lose weight. I was just eating maintenance calories, and I lost 5 pounds pretty quickly. Now I'm trying to get used to packing away the food. I totally pigged out last week, and my squat and deadlift both jumped 20 pounds! W00T!