Sep 3, 2013 1:07am
1. Increase the protein in your diet.
2. Work your muscles.
Make sure the weight you gain comes mostly from protein. You can use weights to build muscle.
Also, before getting into this, make sure you're fit. If you are not, start with stretching and cardio.
Whatever changes you make, make them gradually. This will help to avoid negatively affecting your metabolism and injuring yourself. Wait to be comfortable and used to each change before moving to the next level.
Also, before getting protein shakes and bars, try to get all your protein from wholesome food.