I'm 24. and i look too young for my age:-( . i weigh just 45 and my bmi is very low. can anyone tell me how can i put on some weight.

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.