In all of the previous life stages, the individual is moving toward maturity. In middle adulthood, the adult has reached maturity. The adult is fully a grown up. At this stage in life however, middle-aged adults must confront the beginnings of physical decline. There is still considerable vigor and vitality in middle adulthood as well as considerable potential for psychological growth. Nonetheless, the signs of a declining body are unavoidable. Middle-aged adults confront a loss of physical strength and energy, minor aches and pains that occur more easily and take longer to go away than ever before, and various losses in sensory and cognitive abilities. There are significant consolations to middle adulthood, however. Decades of life experience promote general wisdom, the capacity to understand the world as a whole, integrated system. There is greater emotional maturity as well, an understanding of one’s self and others in more tempered and thoughtful ways. In middle adulthood, we are older but wiser.

While middle-aged adults retain the physical abilities necessary to conduct their daily lives, there are unmistakable signs of aging. There is a loss of lean body mass, including both muscle and bone, and a concomitant gain in body fat. On average, women’s abdomens increase by about thirty percent and men’s by about ten percent from early to middle adulthood. There are also changes in the layers of the skin, such that elasticity is lost, the skin loosens and wrinkles form. Gray hair is caused by a reduction of melanin in the hair follicles.

There are also important changes in the reproductive system, especially for women. Menopause occurs on average at age fifty-one but most women experience considerable hormonal changes for several years before. These changes affect sleep, temperature regulation, bone density, and sexual function. It is important to note that physical health in middle adulthood is strongly influenced by health-related behaviors. A healthy diet (i.e., one rich in fruits, vegetables, whole grains, and lean proteins), regular exercise, and avoidance of smoking and excessive alcohol can greatly moderate the effects of aging.