Also have a post workout protein shake. That's right, in addition to a carb drink during the workout, you should have a protein shake immediately after your workout. Post workout protein does wonders for recovery and allows your hard work in the gym to pay off. Adding some carbs to your shake (berries, honey, almond milk) is a way to sneak in some extra calories and make your shake delightfully delicious. Push your calorie intake until you start gaining mass. You want to do the exact opposite of someone trying to lose weight. Add about 500 calories to your diet and see if your weight starts to increase. If it doesn't, try reducing your non-resistance exercise (any cardio-based exercise). Still no weight-gain? Add another 500 calories to your diet. Repeat until the scale starts to move.