Chronological age is the number of years that a person has lived on earth whereas biological age is the age which a person appears to be. Biological age is at times referred to as physiological age and many factors are taken into consideration which includes exercise, diet as well as sleeping habits. The most common change that occurs during middle adulthood is the middle age spread. This is the weight gain that occurs in the middle adulthood. This has been attributed to change in hormones and reduced metabolism thugs we lose less fat. Another change is ability and mobility becomes a problem. The loss of cortical bones is also associated with decline of hormones, in women its hormone estrogen. Generally, the body’s immune system becomes weakened with age and due to lack of physical activity the body is exposed to several chronic illnesses. The fat build up may also result in heart diseases such as stroke and heart failure. Skin will also dry out, and wrinkles start forming. Especially in sensitive areas such as the facial area. Gay hair is another biomarker of aging and is due to production of less melanin by the hair follicles. The pros of physical aging include wisdom because of life experiences, people especially the young give you much more respect and one can make better decisions on life. The cons include decreased ability to carry out tasks due to decline in strength, susceptibility to diseases such as heart diseases and diabetes.