The body’s functions slow down with age and its ability to replace worn out cells is reduced. The metabolic rate slows and can decline up to thirty percent over a lifetime. This results in decreased caloric needs which can be complicated by changes in an older person’s ability to balance food intake and energy needs. Even with a decreased caloric need, many older people have difficulty getting sufficient calories which can eventually lead to chronic fatigue, depression and a weakened immune system. As we age, our body composition changes with a decrease in lean tissue mass (as much as 25%) and an increase in body fat. Such changes can be further accelerated because older adults utilize dietary proteins less efficiently and may actually need a greater than recommended amount of high quality protein in their diet to maintain lean tissue mass.
Bones also become less dense and eyes do not focus on nearby objects as they once did and some go cloudy with cataracts. Poor dentition is common and hearing, taste and smell are less acute. Digestion is affected because the secretion of hydrochloric acid and enzymes are diminished. This in turn reduces intrinsic factor synthesis, which leads to a deficiency of vitamin B12. The tone of the intestines also slows down and the result may be constipation or in several cases diarrhea.