What i should do to increase ma weight ? ma dr told me that i have a problem of absorption. ma weight is 45 kg and ma hight is 165 cm

Depends: If you are in your teenage years or if you are referring to a child, a good healthy diet with plenty of exercise and activity can maximize your chances to attain your full potential. However, if you are an adult, there isnt much you can do as your bones have fused leaving no room for further growth.

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.