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General Principles in Older Adults
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Weight loss and malnutrition are common in older adults. Previous studies have reported that 17% to 65% of hospitalized geriatric patients and up to 59% of geriatric residents in institutions suffered from malnutrition. Over the past 15 years, however, obesity in older adults has increased. Despite an overall weight increase, obese older patients lose lean mass and remain at risk for functional decline and other medical complications much as do older adults with involuntary weight loss. There remains controversy regarding the appropriateness of advocating for weight loss in older adults with body mass index (BMI) greater than 35, which is discussed later in this chapter.
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In general, body weight in men tends to increase from age 30–60, plateaus for the next 10–15 years, and then slowly declines. In women, the pattern of weight change is similar, except that changes occur approximately 10 years later in life. Lean body mass (primarily skeletal muscle) begins to decline by middle age as a result of many factors, including decreasing exercise and age-related declines in hormone levels (eg, testosterone, estrogen, and growth factors), metabolism, and muscle protein synthesis. Even during healthy aging, daily energy requirements decline with age. This is a result of decreases in muscle mass and decreases in physical activity. There are many formulas to estimate resting caloric needs (Table 68–1). All of these estimations should take into account activity levels and underlying illness severity.
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Recommended Dietary Allowances for Older Adults
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Recommended dietary allowances (RDAs) of vitamins and minerals for geriatric patients are not significantly different from those for middle age adults (Table 68–2). Notable differences include recommendations for calcium and vitamin D intake. For men older than age 70 years, recommended calcium intake increases from 1000 mg/day to 1200 mg/day. For both men and women older than age 70 years, the recommended daily dosage of vitamin D (cholecalciferol) increases from 600 IU to 800 IU. Most nonprescription multivitamins provide adequate vitamins and minerals except for calcium and vitamin D. Supplementation with additional calcium and vitamin D remains warranted.
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