While it used to be defined by social influence, an attractive woman's figure is today largely based around several different metrics. One of the most important ones is called the waist-to-hip ratio or WHR.
Regardless of whether a person is fat or slender, the ideal relation between these two parts of the body should be around 0.7 in order to look attractive. The ratio is calculated by dividing the circumference of the waist by the circumference of the hips. Women naturally tend to have a much lower WHR figure than men to begin with. As girls become women, the presence of increased estrogen levels cause the pelvis to grow.
This causes a fat distribution pattern where fat tends to attract to the buttocks and the thighs, which causes the WHR to deviate away from that ideal figure. This ideal is unrealistic, but there are a few things that can be done to amend the issue.
Surgical breast implants can amend the figure and round out the body's fat distribution pattern, which also has the benefit of increasing the bust size. Modern beauty trends have demanded an increasingly large bust region. Naturally there are also other ways to surgically alter the features and redistribute or remove pockets of fat if necessary to change someone's appearance.
So far a majority of studies that look at an attractive woman's physique have taken corpulence, pelvic and waist width and bust size into consideration. One other metric also influences how people physically judge women.
Long legs are considered physically attractive, and legs have been artificially lengthened for a very long time by wearing high heel shoes. Of course, this is only one of several different metrics that people elect to judge women by. Amending one area might help to shore up the look of the others as well.