The average 5'9" female should weigh anywhere between 131 to 160 pounds, and the average 5'9" male should weigh anywhere between 144 to 176 pounds to be considered healthy. Depending on whether the individual is underweight or overweight, changes should be made to one's diet and daily activity level.
The range for a healthy weight is attributed to bone structure and the content of water, muscle and fat in the body. Keep in mind that muscle has a greater density than fat. To determine whether one's weight is healthy, it is important to calculate body mass index and to also seek professional help from a physician or nutritionist.