Im 24 and i need to gain weight how do i do it?

Diet and muscle mass: To gain weight you have to consume more calories than you are burning. Do this in a healthy way though. Don't choose junk or fast food. Keep a well balanced diet and make sure you are getting all the nutrients you need. Don't cut out exercise as it is very good for you. Weight lifting and other muscle building exercises can help you increase your body mass.

If healthy, protein: If you are feeling well, and ideally have been evaluated by a physician recently to be sure you do not have a metabolic condition (such as thyroid disease or diabetes) and are not taking stimulant medications, then adding a protein supplement to your regular diet--without reducing your usual intake--can help. This can be as a snack bar, meal-replacement bar, or powder you add to drinks.