What are the causes of unintentional weight loss?

From the Guidelines

Unintentional weight loss is most commonly caused by cancer, gastrointestinal disorders, endocrine disorders, infections, psychological conditions, medication side effects, neurological conditions, and age-related factors, and it is crucial to seek medical evaluation promptly to diagnose and treat the underlying cause effectively. The causes of unintentional weight loss can be multifaceted, including:

• Cancer, where malignant cells increase metabolic demands and produce substances that suppress appetite 1
• Gastrointestinal disorders like celiac disease, inflammatory bowel disease, or peptic ulcers that interfere with nutrient absorption
• Endocrine disorders such as hyperthyroidism, diabetes, or adrenal insufficiency that alter metabolism
• Infections like HIV/AIDS, tuberculosis, or parasitic infections that increase energy expenditure
• Psychological conditions including depression, anxiety, or eating disorders that affect appetite and eating behaviors
• Medication side effects from drugs like chemotherapy agents, certain antidepressants, or stimulants
• Neurological conditions such as Parkinson's disease or dementia that impact eating ability
• Age-related factors including decreased sense of taste and smell, dental problems, or social isolation Chronic diseases like heart failure, COPD, or kidney disease can also cause weight loss through increased energy demands or protein loss 1. When experiencing unexplained weight loss (typically defined as losing more than 5% of body weight over 6-12 months), it's essential to seek medical evaluation promptly, as early diagnosis of the underlying cause can lead to more effective treatment 1. In the context of cancer, cachexia is a common cause of unintentional weight loss, characterized by a loss of skeletal and visceral muscle mass, and is associated with a poor prognosis 1. A combination therapy approach, including nutritional support, pharmacological interventions, and other treatments, may yield the best possible outcomes for patients with cancer cachexia 1. Overall, unintentional weight loss is a complex issue that requires a comprehensive evaluation and treatment plan to address the underlying cause and improve patient outcomes.

From the FDA Drug Label

The most frequently reported adverse experiences in patients with AIDS during placebo-controlled clinical trials involved the CNS and were reported by 33% of patients receiving dronabinol capsules. Common Adverse Reactions The following adverse reactions were reported in clinical trials at an incidence greater than 1% System Organ Class Adverse Reactions Gastrointestinal Abdominal pain*, nausea*, vomiting* Less Common Adverse Reactions The following adverse reactions were reported in clinical trials at an incidence less than or equal to 1%. System Organ Class Adverse Reactions Gastrointestinal Diarrhea, fecal incontinence, anorexia, hepatic enzyme elevation

Unintentional weight loss can be caused by several factors, including:

• Anorexia (loss of appetite)
• Nausea and vomiting
• Abdominal pain and diarrhea These adverse reactions may lead to decreased food intake and subsequent weight loss. 2

From the Research

Causes of Unintentional Weight Loss

• Nonmalignant diseases are more common causes of unintentional weight loss in older adults than malignant causes, although malignancy accounts for up to one-third of cases 3
• Medication use and polypharmacy can interfere with the sense of taste or induce nausea and should not be overlooked as causative factors 3
• Social factors such as isolation and financial constraints may contribute to unintentional weight loss 3
• Somatic and functional causes of weight loss, as well as iatrogenic causes like side-effects of medication, should be considered 4
• Malignancies, nonmalignant gastrointestinal disorders, and psychiatric disorders are common causes of unintentional weight loss in community-dwelling adults 5
• Depression, cancer, cardiac disorders, and benign gastrointestinal diseases are leading causes of involuntary weight loss in the elderly 6
• A specific cause is not identified in approximately one quarter of elderly patients with unintentional weight loss 6

Diagnostic Work-up

• A readily identifiable cause is not found for 6% to 28% of cases, and recommended tests include age-appropriate cancer screenings, complete blood count, basic metabolic panel, liver function tests, thyroid function tests, and others 3
• Referrals to medical specialists for diagnostics and the role of dieticians in screening and treatment should be considered 4
• A reasonable work-up includes tests dictated by the history and physical examination, a fecal occult blood test, a complete blood count, a chemistry panel, an ultrasensitive thyroid-stimulating hormone test, and a urinalysis 6

Treatment

• Treatment should focus on the underlying cause if known, and dietary modifications that consider patient preferences and chewing or swallowing disabilities should be considered 3
• Appetite stimulants and high-calorie supplements are not recommended, and treatment should focus on feeding assistance, addressing contributing medications, providing appealing foods, and social support 3
• High caloric dietary foods may be necessary when functional decline is obvious, although there is hardly indication for prescribed medication 4
• Management is directed at treating underlying causes and providing nutritional support, considering the patient's environment and interest in and ability to eat food, the amelioration of symptoms, and the provision of adequate nutrition 6