B 15 Things You Should Know About I 1. The average breast weighs 1.1 lbs and contains 45% of the body’s total fat. 2. Just like the penis, breasts swell up when aroused. The average female nipple is 3/8" long when erect. 4. um hymn '» in America is a 360. 5. These sizes would be unattractive in the Middle """ª'ªªkªªª' Ages as small, wide set breasts were considered perfection back then. 6. In 2008, there were 307,230 breast enlargements performed in the US.