Once a person is past puberty, there is no way to make his or her legs longer. For most women, puberty ends between the ages of 16 and 20. Men sometimes continue growing into their early 20s.
Longer legs require longer leg bones. Once puberty ends, the bones of the human body stop growing. However, diet and exercise can help a person's legs look leaner, which can create the appearance of longer legs. Before and during puberty, regular exercise helps grow healthy bones and muscles, which can encourage a young body to achieve its full-growth potential. Exercise also helps adults stave off conditions, such as osteoporosis, which can cause bone mass to decrease.