Advancing age is associated with a remarkable number of changes in body composition, including reduction in lean body mass and increase in body fat. Decreased lean body mass occurs primarily as a result of losses in skeletal muscle mass, a highly malleable tissue that is a central factor in whole-body health. Skeletal muscle accounts for approximately 45–50% of body mass and plays a fundamental role in movement, oxygen consumption, and the production of energy.
Loss in muscle mass accounts for the age-associated decreases in basal metabolic rate (BMR), the amount of energy that is expended at rest after the digestive system has been inactive for about 12 hours - the rate of one’s metabolism when waking in the morning after “fasting” during sleep, muscle strength, and activity levels, which, in turn are the cause of the decreased energy requirements of the elderly.
The BMR provides enough energy for the brain and central nervous system, heart, kidneys, liver, lungs, muscles, sex organs, and skin to function properly. For people that are sedentary, sitting at desks all day long, sitting in a chair or on a sofa for long periods of time, the main determinant of energy expenditure is fat-free mass (lean mass and skeletal muscle mass) which declines by about 15% between the ages of 30 and 80 years old.
It also appears that declining energy needs are not matched by an appropriate decline in the energy intake (derived from food), with the ultimate result being increased body fat and abdominal obesity, thought to be directly linked to the greatly increased incidence of non-insulin-dependent diabetes among the elderly.
Regularly performed exercise can affect nutrition needs and functional capacity in older age groups
Aerobic Exercise
Aerobic exercise has long been an important recommendation for the prevention and treatment of many of the chronic diseases typically associated with old age. These include non-insulin-dependent diabetes mellitus (NIDDM) (and impaired glucose tolerance), hypertension, heart disease, and osteoporosis. Regularly performed aerobic exercise increases the maximum capacity to take in and use oxygen during exercise and insulin action.
Exercise and Carbohydrate Metabolism
Carbohydrates are an excellent source of energy for active people, but for those of us living a more sedentary lifestyle, intake of excessive amounts of carbohydrates has not only become unnecessary but can be the harbinger of ill-health and disease. Because we spend a good deal of our days sitting and not being active, even when we’re choosing whole foods we can still consume more energy than our body needs. In fact, the overconsumption of carbohydrate in excess of the body’s needs is where we fall into ill health. Excess carbohydrate intake places a large metabolic load on the body. When the body constantly has high levels of blood sugars (the end point of food sugar and starch) to deal with over time, this leads to weight gain, poor metabolic health an increased risk of heart disease and type 2 diabetes, a complex endocrine disorder characterised by abnormally high concentrations of circulating glucose. This disease now affects millions of people worldwide.
Strength Training
Although endurance exercise has been the more traditional means of increasing cardiovascular fitness, strength or resistance training is an important component of an overall fitness program. This is particularly important in the elderly in whom loss of muscle mass and weakness are more prominent.
Resistance training is based on the principle that muscles will work to overcome a resistance force. When you do resistance training repeatedly and consistently, your muscles become stronger. Different types of resistance training includes free weights such as dumbells, resistance bands or your own body weight used for squats, push ups etc.
Protein Needs and Aging
Inadequate protein intake contributes to muscle wastage, and can impact physical function and increase the risk of frailty and mortality through falls. This risk is again increased in older adults with obesity, who may be unable to exercise or move freely, as their weight may mask the problem.
A study in Sheffield found that half the older adults studied were not consuming enough protein to reach national recommendations, 0.75 grams of protein per kilogram of their body weight per day. Many experts believe that older adults need higher protein intake than the UK recommendations, with international organisations suggesting 1.2 grams of protein per kilogram of their body weight per day. Less than 15 percent of the study group met this age-specific recommendation.
A useful strategy for people of mid to older age is to include a source of protein with every meal. As an indicator, you can get 32 grams of protein from a chicken breast and 6 grams from an egg. Older adults can easily bolster their protein intake by eating a high-protein breakfast cereal or an egg and slice of brown toast for breakfast. People should also think about including sustainable and plant-based sources of protein in their diet such as beans, lentils, tofu and peas.
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