Growth hormones are secreted from the pituitary gland during puberty. Due to this increase in height and weight is seen in both girls and boys. In girls, the growth spurt starts between the ages of 10 and 13. After this, they grow just 1 to 2 inches more in a year or two after. This is when they reach their adult height. They reach their adult height by the age of 16. During puberty, the peak height that boys reach is 92 percent of their adult height and they reach their adult height by the age of 18.