Treatment of Decreased Appetite in Adults
The treatment of decreased appetite in adults must first identify and address the underlying cause—whether psychiatric (eating disorders), medical (cancer, chronic disease), or medication-related—with treatment strategies ranging from eating disorder-focused psychotherapy for anorexia nervosa to appetite stimulants only in select cases of cancer cachexia or AIDS-related anorexia, while avoiding pharmacologic interventions in most other contexts due to limited efficacy and significant adverse effects.
Initial Diagnostic Approach
The first critical step is determining the etiology of decreased appetite, as this fundamentally directs treatment:
Psychiatric causes require comprehensive evaluation including weight measurement, quantification of eating behaviors, assessment for co-occurring psychiatric disorders, vital signs (temperature, heart rate, blood pressure including orthostatic measurements), and laboratory assessment (complete blood count, comprehensive metabolic panel including electrolytes, liver enzymes, and renal function) 1.
Medical causes in older adults commonly include pulmonary and cardiac diseases, cancer, dementia, alcoholism, and depression 2. In hospitalized patients, protein-energy malnutrition contributes to adverse outcomes 3.
Medication-induced appetite loss is particularly common in older adults and requires careful medication review 1, 2.
Treatment by Underlying Condition
Eating Disorders (Anorexia Nervosa)
For adults with anorexia nervosa, eating disorder-focused psychotherapy is the primary treatment, which must include normalizing eating and weight control behaviors, restoring weight, and addressing psychological aspects such as fear of weight gain and body image disturbance 1.
Patients requiring nutritional rehabilitation need individualized goals for weekly weight gain and target weight 1.
A comprehensive, culturally appropriate, person-centered treatment plan incorporating medical, psychiatric, psychological, and nutritional expertise through a coordinated multidisciplinary team is essential 1.
Critical pitfall to avoid: Do not treat gastrointestinal symptoms of anorexia nervosa as primary gastroparesis requiring prokinetic agents like metoclopramide, as this exposes patients to serious neurological risks (extrapyramidal symptoms, tardive dyskinesia) without addressing the underlying eating disorder pathology 4. Nutritional rehabilitation is the primary treatment for gastrointestinal symptoms, which typically improve with weight restoration 4.
Cancer Cachexia
For adults with advanced cancer experiencing appetite loss, weight loss, and/or lean body mass loss, treatment options are limited:
Nutritional interventions including dietary counseling and supplements should be considered, though evidence for improved outcomes is limited 1.
Pharmacologic appetite stimulants (megestrol acetate, corticosteroids, cannabis/cannabinoids) may be considered but have limited efficacy and considerable side effects 1, 5.
The American Society of Clinical Oncology guideline addresses this population specifically, recognizing the complexity of managing cancer-related appetite loss 1.
AIDS-Related Anorexia
Dronabinol is FDA-approved for treating loss of appetite (anorexia) in adults with AIDS who have experienced weight loss 6.
Dronabinol is typically taken twice daily, 1 hour before lunch and 1 hour before dinner 6.
Important safety warnings: Dronabinol can cause worsening psychiatric symptoms (particularly in those with mania, depression, or schizophrenia), problems thinking clearly, hemodynamic instability (blood pressure changes, syncope, tachycardia), and has abuse potential as a controlled substance (Schedule III) 6.
Elderly patients have greater risk of psychiatric symptoms, cognitive problems, blood pressure changes, and falls 6.
Older Adults Without Specific Eating Disorder or Cancer
For older adults with decreased appetite from general medical causes:
Address modifiable factors: Review and potentially discontinue appetite-suppressing medications, treat depression, manage gastrointestinal disturbances, and encourage physical activity and socialization 2, 7.
Nutritional strategies: Small, frequent meals, high-calorie supplements, and meals tailored to cultural preferences and personal goals may increase food intake and quality of life 1, 2, 7.
In older adults with diabetes: Metformin can cause gastrointestinal side effects and appetite reduction; reduction or elimination may be necessary for those experiencing persistent symptoms 1. Therapeutic diets in long-term care may inadvertently decrease food intake and contribute to unintentional weight loss 1.
Pharmacologic appetite stimulants (megestrol acetate, mirtazapine, dronabinol) have been used but require careful consideration of dosage, side effects, and proper patient selection 5.
Depression and Cognitive Impairment
Depression is significantly associated with poor appetite in both Alzheimer's disease and mild cognitive impairment patients, making treatment of underlying depression a priority 8.
Difficulty maintaining attention while eating is also associated with appetite loss in these populations 8.
In AD patients specifically, lower vitality, more comorbidities, non-use of antidementia drugs, and use of psychotropic drugs are associated with poor appetite 8.
Key Clinical Considerations
Avoid indiscriminate use of nutritional support: Recent evidence from critical care demonstrates harmful effects when parenteral nutrition is used without careful patient selection, suggesting that loss of appetite in acute illness may represent an adaptive, protective response that improves cellular recycling (autophagy) 3.
Timing matters: In acutely ill medical inpatients, the selection, timing, and doses of nutrition should be evaluated as carefully as any therapeutic intervention, maximizing efficacy while minimizing adverse effects 3.
Multidisciplinary approach for eating disorders: Treatment plans must incorporate medical, psychiatric, psychological, and nutritional expertise, as outcomes depend on addressing all dimensions of the disorder 1.