Breasts are made up of adipose tissue and of course the mammary glands for making milk when breast feeding, underneath that is the pectoral muscle group. So if women want to make their breasts bigger they can do lifting exercises to increase muscle mass, however women are not known to have bulky muscle mass like men, so the increase will not be very much, you can cause the mammary glands to be engorged to produce milk by increasing the hormone lactin, and this can be done thru medication, but you would also have to pump your breasts like you would if you were nursing to keep from first being painfully full, and secondly to keep the hormone affects going, become a donor of breast milk for babies in the hospital. The last way is the one known by everyone, Breast augmentation or implants....Or I guess if you want you can get obese and add more adipose (fat tissue) but then again that goes to places you don't want, I don't recommend the gaining weight. There is your ways to increase breast size...