Am Fam Physician. 2021;104(1):34-40
Patient information: See related handout on untentional weight loss in older adults.
Author disclosure: No relevant financial affiliations.
Unintentional weight loss in people older than 65 years is associated with increased morbidity and mortality. Nonmalignant diseases are more common causes of unintentional weight loss in this population than malignant causes. However, malignancy accounts for up to one-third of cases of unintentional weight loss. Medication use and polypharmacy can interfere with the sense of taste or induce nausea and should not be overlooked as causative factors. Social factors such as isolation and financial constraints may contribute to unintentional weight loss. A readily identifiable cause is not found for 6% to 28% of cases. Recommended tests include age-appropriate cancer screenings, complete blood count, basic metabolic panel, liver function tests, thyroid function tests, C-reactive protein level, erythrocyte sedimentation rate, lactate dehydrogenase measurement, ferritin, protein electrophoresis, and urinalysis. Chest radiography and fecal occult blood testing should be performed. Further imaging and invasive testing may be considered based on initial evaluation. When the initial evaluation is unremarkable, a three- to six-month observation period is recommended with follow-up based on clinician and patient preferences. Treatment should focus on the underlying cause if known. Dietary modifications that consider patient preferences and chewing or swallowing disabilities should be considered. Appetite stimulants and high-calorie supplements are not recommended. Treatment should focus on feeding assistance, addressing contributing medications, providing appealing foods, and social support.
Weight loss in older adults can be intentional or unintentional. Unintentional weight loss in adults older than 65 years is generally defined as a 5% or greater loss of body weight in a six- to 12-month period and is associated with increased morbidity and mortality.1–3 Weight loss can be assessed by numerical documentation or, if no baseline weight is available, corroboration with a change in clothing size or from a relative may be used. The patient or relative should provide an estimate of the weight loss.2,3 Unintentional weight loss in older adults can be classified as unexplained, unintentional weight loss when no definable cause is found or as unintentional weight loss with a known origin.
| Clinical recommendation | Evidence rating | Comments |
|---|---|---|
| Unintentional weight loss of 5% or greater within six to 12 months is associated with increased morbidity and mortality in older adults and should prompt evaluation.2,3,8,13,15 | B | Consistent findings from multiple prospective cohort studies with good follow-up |
| The initial evaluation for unexplained, unintentional weight loss in older adults should include history, physical examination, laboratory tests, chest radiography, fecal occult blood testing, and possibly abdominal ultrasonography.8,11–16 | C | Findings from three retrospective and four prospective studies |
| If initial test results are negative, close observation for three to six months is justified. Annual follow-up should be considered after the observation period.2,8,12 | C | Consistent findings from three prospective trials |
| Recommendation | Sponsoring organization |
|---|---|
| Avoid using prescription appetite stimulants or high-calorie supplements for the treatment of anorexia or cachexia in older adults; instead, optimize social supports, discontinue medications that may interfere with eating, provide appealing food and feeding assistance, and clarify patient goals and expectations. | American Geriatrics Society |
Cachexia syndrome is associated with weight loss (greater than 5%) within 12 months attributed to a known chronic illness such as cancer, chronic obstructive pulmonary disease, or chronic kidney disease. To diagnose cachexia syndrome, three of the following characteristics must be present: fatigue, anorexia, low fat-free mass index (amount of muscle mass to height), decreased muscle strength, and abnormal laboratory testing such as low serum albumin levels, anemia, or elevated inflammatory markers.2,4 Challenges in identifying weight loss in older adults include pre-existing obesity and subsequent intentional weight loss from diet and exercise, an expected decline in muscle mass between 50 and 60 years of age, normal daily weight fluctuations, and variations in health care systems' documentation of patient weight.1
Etiologies
The pathophysiology of unintentional weight loss is not well understood. Multiple studies have looked at inflammatory cytokines such as tumor necrosis factor alpha, interleukin-1 beta, interleukin-6, and gut hormones such as cholecystokinin, glucagon-like peptide, and ghrelin.5,6 Although evidence supports that inflammation and inflammatory mediators play a role in weight regulation, the exact mechanism is not understood.7
Body composition and lean body mass decrease with age. Lean body mass can decrease up to 0.7 lb (0.3 kg) per year between 20 and 30 years of age. Fat mass continues to increase until 65 to 70 years of age. Therefore, total body weight usually peaks at 60 years of age with only small decreases after that. The normal reduction in appetite and food intake that occurs with aging should not lead to weight changes substantial enough to be confused with unintentional weight loss.8
Unintentional weight loss in older adults is a diagnostic challenge. There are no validated clinical guidelines, and the differential diagnosis is broad.2 However, once identified, unintentional weight loss should be evaluated. Patients 18 years and older presenting with weight loss are up to 12.5 times more likely than those without weight loss to have cancer. For people older than 60 years, more than one in 10 presenting with weight loss will be diagnosed with cancer. There is an overall risk of 11% to 14% in men and 3% to 7% in women above the normal age-associated cancer risk.1 The lifetime risk of cancer in adults by age is 24.4% (55 to 64 years), 28.2% (65 to 74 years), 18.2% (75 to 84 years), and 8.0% (older than 84 years).9 Weight loss is associated with increased frailty, recurrent falls, and overall worse health outcomes.10
In community-dwelling older adults, unintentional weight loss causes are most often classified as organic or psychosocial. Prospective and retrospective studies in inpatient and outpatient settings have demonstrated that overall non-malignant diseases are more common causes of unintentional weight loss than malignant causes. However, malignancy accounts for up to one-third of cases of unintentional weight loss. After the initial evaluation, the etiologies of unintentional weight loss are malignancy (19% to 36%), with gastrointestinal cancer being the most common, nonmalignant gastrointestinal disease (9% to 45%), and psychosocial disorders (9% to 24%).2,3,11–19 Table 1 lists the common disorders within these broader categories.2,3,12–17 Unintentional weight loss that is unexplained after an initial evaluation ranges from 6% to 28% of cases.2,3,12–16
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