In the 40 years after a man turns 30, he can lose an inch in height, according to the University of Arkansas Medical Sciences. During those same 40 years, the average woman can lose 2 inches. After age 80, both men and women often lose another inch.
The reduction in height is due to factors including osteoporosis and the loss of cartilage in the spinal column, explains Dr. Pham Liem for the University of Arkansas Medical Sciences. As many adults age, they also lose muscle mass and gain fat, further reducing their height. A loss of 1 to 2 inches in height in a single year indicates the individual is at risk for fractures of the spine or hip. In men, this type of loss of height indicates an increased risk for a heart attack. While lifestyle changes, such as stopping smoking, limiting alcohol use and eating a better diet can help to prevent the shrinking height, they cannot add back height that is already lost.
Humans also lose height on a daily basis, according to KidsHealth. The human body is shorter at night than in the morning. Gravity pulls the body weight toward the Earth and forces fluids from the discs in the spine. However, this type of loss in height is temporary as the fluids are replenished at night when the individual sleeps, restoring him to his original height.