How to increase the Height After 18 years - 5 simple Things can Help you. At the age of eighteen, an average adolescent body undergoes enormous hormonal changes. The human body is ruled by hormones and hormones that in turn are determined by our lifestyle. To reach height, the most important hormone that is used is human growth hormone (HGH). This causes the growth of bones and muscles. Some believe that 18 is the last stop for the HGH. But that is not true. One can grow as long as the hormone is excreted. In order for the hormones to take action, we must therefore follow the basic few steps that ensure height gain. Here are our 5 simple things to increase the Height after 18 years. Have a balanced meal. Exercises - Free hand stretching, Swimming, Gymnastics. Enough sleep. Avoid smoking & drinking. Genetic factor.