Weight loss

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Chapter 24 WEIGHT LOSS

• Weight loss is defined as >5% loss of usual body weight over a period of 6–12 months.

• Body mass index (BMI) is defined as body weight in kg divided by height in metres squared (kg/m²).

• Weight loss in elderly people is largely caused by a reduction in food intake and contributes to morbidity and mortality.

• Potential causes of weight loss are strongly influenced by the age at presentation.

• A cause for weight loss can be established in at least 75% of patients.

• Management is determined by the cause. Depression is the most common treatable cause.

INTRODUCTION

The major influences on body weight are caloric intake, intestinal absorption and utilisation. The purpose of this chapter is to outline an approach to the diagnosis and management of weight loss, particularly in adults.

An important message is the need for greater attention to undernutrition as a cause of weight loss. In the elderly, weight loss is strongly associated with functional decline and mortality.

Definitions

In research studies, weight loss may be defined as a weight loss of >5% of usual body weight over a period of 6–12 months. Weight loss >10% is usually associated with protein–energy malnutrition while weight loss >20% implies severe protein–energy malnutrition and significant organ dysfunction. One quantitative measure of nutritional status is that of body mass index (BMI). This is defined as body weight in kg divided by height in metres squared (kg/m²). A BMI lower than 17 is consistent with undernutrition. Other anthropometric measures include arm circumference and triceps skin fold thickness, but these are affected, at least to some extent, by skin changes associated with ageing.

Prevalence

Features of undernutrition or significant weight loss have been documented in at least 10% of elderly patients attending outpatient clinics, 25% of elderly inpatients needing acute care and 40% of patients in nursing homes and other institutions.

PATHOPHYSIOLOGY

The weight loss that occurs with ageing is largely caused by a reduction in food intake. This has been attributed to a variety of factors including age-related losses in taste and smell, age-related decreases in opioid receptors and enhanced sensitivity to the satiating effects of cholecystokinin. Other factors may include changes in the secretion of leptin and sex hormones and age-related changes in intestinal absorption, sometimes mediated by changes in gastrointestinal motility. In the setting of acute and chronic disease, anorexia and weight loss can be caused by a variety of factors including ill health, weakness and side effects from medication. Some of these effects may be mediated by elevated levels of cytokines such as interleukins and tumour necrosis factor and by elevated levels of corticotrophin-releasing factor. At a practical level, at least 20% of inpatients in acute hospitals have a nutrient intake of <50% of their calculated maintenance energy requirements.

CAUSES OF WEIGHT LOSS

Potential causes of weight loss are strongly influenced by the age at presentation. For example, in young adults, unintentional weight loss is often due to psychiatric disorders such as depression, anorexia nervosa, bulimia, psychoses and substance abuse. In contrast, weight loss in the elderly is often due to multiple factors including social isolation, bereavement, dementia, depression, poor dentition and side effects from drugs. In middle age, there may be a greater contribution from cancer, alcoholism, endocrine disorders and chronic inflammatory disorders. Cancer is diagnosed in up to 25% of patients with weight loss over the age of 50 years. Some of the factors that contribute to weight loss are outlined below and are summarised in Figure 24.1.

• Anorexia. Many acute and chronic disorders are associated with a decrease in appetite. These include infections, cancer, peptic ulceration, renal impairment, liver disease, alcoholism and cardiac failure. Anorexia can also be a side effect of medication.

• Oral disorders. Eating may be impaired by oral factors such as absent or ill fitting dentures, dental decay, periodontal disease and a dry mouth. The latter can be caused by an age-related reduction in salivary secretion, Sjögren’s syndrome and side effects from drugs with anticholinergic activity.

• Swallowing disorders. Swallowing may be impaired by weakness in pharyngeal muscles, by motility disorders of the oesophagus or by benign or malignant strictures of the oesophagus. Of these, the most common is pharyngeal weakness following a cerebrovascular accident.

• Non-malignant gastrointestinal disorders. This group includes disorders such as peptic ulceration, biliary disorders, chronic inflammatory bowel disease, coeliac disease, chronic pancreatitis and bacterial overgrowth in the small intestine.

• Cancer. The most common primary sites are colon, stomach, lung and pancreas.

• Endocrine disorders. These include thyrotoxicosis and hyperparathyroidism.

• Miscellaneous causes. These include chronic infections such as tuberculosis, lung abscess and osteomyelitis and chronic inflammatory disorders such as rheumatoid arthritis, systemic lupus erythematosus and polyarteritis nodosa.

• Psychosocial factors. Psychiatric disorders include depression, anorexia nervosa, bulimia, psychoses and drug addiction. Dementia is also important and may be aggravated by social isolation, bereavement, poverty and insufficient assistance with feeding.

FIGURE 24.1 Factors contributing to weight loss.

ASSESSMENT

A cause for weight loss can be established in at least 75% of patients. This is achieved by history, physical examination and a limited number of targeted diagnostic studies.

• History: should include documentation of weight loss and a detailed review of symptoms relevant to cancer, mental illness and gastrointestinal disease. It should also include information about diet, use of alcohol, prescription and non-prescription medication, social details and, if applicable, information from care-givers.

• Physical examination: focus on the oral cavity and on areas commonly affected by cancer.

• Psychosocial tests: may include the Folstein Mini-Mental State Exam, depression questionnaires and questionnaires related to nutrition, depending on the clinical setting.

• Functional evaluation: may include an assessment of sight, gait, hearing and ability to self-care.

• Laboratory evaluation: screening laboratory tests will usually include a blood count, chemistry profile, thyroid stimulating hormone (TSH), urine tests and a chest X-ray. A low plasma albumin can reflect severe protein deficiency. Additional tests will be influenced by symptoms and results from screening studies but may include investigations such as upper gastrointestinal endoscopy, colonoscopy, ultrasound studies and computed tomography (CT) scans. Normal results from screening tests should be highly reassuring.

MANAGEMENT

The management of individual patients with weight loss will be largely determined by the established or presumed cause. The most common treatable cause is depression. Management options that may increase the intake of food are as listed below.

• Diet. Food intake may increase with more frequent meals, a wider choice in foods or by making food more flavoursome and attractive.

• Assistance with meals. This can include delivered meals (e.g. Meals on Wheels) and assistance with eating for those with various disabilities.

• Oral nutritional supplements. A variety of supplements are available that appear to be helpful in at least undernourished older people.

• Micronutrient supplements. Multivitamin supplements are of potential but unproven benefit. Thiamine supplements should be provided for alcoholics and individual patients may need supplements of folic acid, and vitamins B₁₂, C and D.

• Enteral feeding. This should be considered when swallowing is difficult or unsafe. Feeds can be provided by fine–bore nasogastric tubes or by gastric or jejunal tubes after percutaneous endoscopic gastrostomy (PEG).

• Drugs for anorexia and nausea. A variety of drugs have been used for anorexia including corticosteroids, progestogens, serotonin antagonists, anabolic agents and anticatabolic agents.

PROGNOSIS

High mortality rates have been observed in patients in nursing homes who lose 10% or more of body weight over 0.5–3 years. In relation to morbidity, malnourished patients in acute care hospitals have more complications, longer hospital stays and require longer periods of convalescence.

SUMMARY

The major influences on body weight are caloric intake, intestinal absorption and utilisation. Weight loss may be defined as weight loss of greater than 5% of usual body weight over a period of 6–12 months. BMI provides a quantitative measure of nutritional status. It is defined as body weight in kg divided by height in metres squared (kg/m²). A BMI lower than 17 is consistent with undernutrition.

The weight loss that occurs with ageing is largely caused by a reduction in food intake. Up to 40% of patients in nursing homes and other institutions have features of undernutrition or significant weight loss.

The causes of weight loss include anorexia, oral disorders, swallowing disorders, cancer, endocrine disorders and psychosocial factors (Figure 24.1). A cause for weight loss can be established in 75% of patients.

Assessment should include history, clinical examination, psychosocial tests, functional evaluation and laboratory evaluation.

The various options available for treatment include diet, assistance with meals, nutritional supplements, micronutrient supplements, enteral feeding and drugs for nausea and vomiting.

High mortality rates have been observed in patients in nursing homes who lose 10% or more of body weight over 0.5–3 years.

FURTHER READING

Bouras EP, Lange SM, Scolapio JS. Rational approach to patients with unintentional weight loss. Mayo Clin Proc. 2001;76:923-929.

Gazewood JD, Mehr DR. Diagnosis and management of weight loss in the elderly. J Fam Pract. 1998;47:19-25.

Lankisch P, Gerzmann M, Gerzmann JF, et al. Unintentional weight loss: diagnosis and prognosis. The first prospective follow-up study from a secondary referral centre. J Intern Med. 2001;249:41-46.

Morley JE. Anorexia of aging: physiologic and pathologic. Am J Clin Nutr. 1997;66:760-773.

Rolland Y, Kim MJ, Gammack JK, et al. Office management of weight loss in older persons. Am J Med. 2006;119:1019-1026.

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