Disease-related changes in appetite stem from several physiological and psychological factors. Many chronic illnesses cause systemic inflammation, metabolic changes, and alterations in nutrient uptake that can dysregulate appetite. Neuropsychological factors including stress, depression and thereby a reduced quality of life, also depauperate the process of appetite in chronic disease. Non-cognitive factors like cachexia in cancer, peripheral oedema in heart failure decrease hunger because the question causes general discomfort. In addition, therapies are also known to have side effects such as nausea and change in taste which can lead to worsening of appetite loss. The management of these problems usually requires medical nutrition therapy, symptom control and psychological interventions. 

It is prevalent in chronic conditions: 70% in cancer patients, especially in the terminal stage or those receiving chemotherapy, 40 to 50% in stage 4 and 5 CKD patients, Modest 30-50% in COPD due to energy demand and breathing difficulties, and mild 20-30% in heart failure patients due to fluid accumulation and oedema. 

The changes of appetite are experienced by all age populations though the elderly are more vulnerable. It has been established that gender differences exist, but many of these differences depend on the disease or the study conducted. 

• Inflammatory Responses: Chronic diseases develop the process of inflammation in the body, causing cytokines such as TNF-alpha and IL-6 to impact on the hypothalamus about reduced appetite and shift in metabolism. 
• Metabolic Changes: It may be caused by chronic illnesses like cancer and CKD where there is loss of appetite and increased energy expenditure leading to weight loss and muscle wasting. Chronic diseases also affect normal metabolic activities since they are long-term conditions that tend to alter human bodily functions. 
• Gastrointestinal Disruption: Pathological diseases and any diseases that can cause some form of discomfort either through vomiting or have upset the stomach block hunger due to nausea that affects the absorption of nutrients. 
• Hormonal and Neurotransmitter Changes: Chronic diseases affect traditional physiological complexity of appetite regulation involving hormones like leptin and ghrelin in addition to neurotransmitter medications such as serotonin and dopamine. 

Chronic diseases cause inflammation, which activates cytokines such as TNF-alpha and IL-6 that inhibit the starvation centers in the brain, leading to changes in hunger signals. Both cancer and CKD can lead to cachexia, which leads to severe weight loss and muscle wasting because the body energy use rate is high and the desire to eat is low. 

Conditions like cancer, COPD, and treatments through chemo can make foods unappetizing, and diseases like CKD can aggressively impact one’s digestive system. 

Abnormalities in the hormonal regulation of appetite, particularly the signals of leptin and ghrelin are likely to result in alteration of appetite. 

Disease Severity and Stage: At more advanced stages and especially if it is a severe case, the affected person is likely to lose his/her appetite. 

Inflammatory Markers: As the appetite and the disease severity worsens, the cytokine levels are likely to be high. 

Metabolic Status: Cachexia and poor nutritional status used in this study affect appetite and prognosis. 

Gastrointestinal Health: Conditions such as the nauseating effect or poor digestion also will contribute to reduced appetite. 

Hormonal and Neurotransmitter Levels: Hormonal abnormalities and neurotransmitters for hunger contributors are also include. 

Age Group 

Appetite changes could also be due to chronic diseases such as juvenile idiopathic arthritis or cystic fibrosis in children, adults, and the elderly. In this case, children may develop anorexia and may lose weight whereas, adults may develop anorexia, early satiety and may start to lose weight unintentionally. Older adults may present with many disease-related issues affecting their appetite and uptake of foods due to multiple comorbidities and age-related physiology alterations.  

• Vital Signs: Look for signs of raised intracranial pressure (e. g., headaches in brain metastases), which can affect appetite. 
• Gastrointestinal Exam: Check for vomiting, nausea, abdominal pain or any indicators of disturbance in digestion that might cause changes in food intake. 
• Nutritional Status: Assess indicators of nutritional compromise including skin dryness, hair breakage, and delayed or stalled healing. 
• Body Mass Index (BMI): Use BMI to monitor changes in weight as well as the nutritional state of the body. 

• Cancer 
• Chronic kidney disease 
• Heart failure 
• Chronic obstructive pulmonary disease

• Acute: The development of anorexic symptoms over a short period may surface when a chronic illness becomes acute or exacerbation of a chronic ailment, for instance, COPD or acute renal failure. 
• Chronic: In progressive diseases like cancer, CKD and heart failure, appetite loss is usually gradual mostly at initial stages. Some psychological effects may indicate a long-term alteration in feeding behaviour, which is gradual and may take months or years. 

Control the Chronic Disease: Ensure these core disorders are well managed (e.g., cancer, chronic kidney disease) and then address symptoms such as pain, nausea, and depression to enhance appetite. 

Nutritional Support: Modify the diet according to patient’s choice and provide small high-energy dense and high-protein meals and if needed appetite enhancers such as megestrol acetate or corticosteroids. 

Psychosocial Support: Psychotherapy or counseling to address the psychological component, and mutual support through purposeful psychological support groups. 

Medical Interventions: Promote appetite stimulating agents like cannabinoids and antidepressants; Consider tube feeding in very severe conditions where oral intake is compromised. 

Monitoring and Follow-Up: Weight monitoring at least weekly and/or other anthropometric measures, nutritional history, and corresponding changes in the treatment plan.

Nutrition

Physical Medicine and Rehabilitation

• Dietary Adjustments: The patient should consume small meals and snacks between 5 to 6 times a day, which should be preferred foods and contain optimal nutrients. 
• Behavioural Strategies: Develop precise meal schedules and utilize methods that help to relax the patient’s body and mind. 
• Psychosocial Support: Participate in counselling and support groups and social breakfast. 
• Environmental Modifications: Treat the eating areas in a way that is comfortable for you and your tools should be adjustable. 
• Physical Activity: Frequently, it is advisable to introduce a gentle form of physical activity that helps to trigger appetite. 

Nephrology

Nutrition

• Megestrol Acetate: It is a synthetic progestin which is prescribed to stimulate the eating potential and weight gain in cancer cachexia, AIDS and other wasting diseases. A cancer patient who suffers from a poor appetite and significant weight loss may be administered megestrol acetate to increase his or her appetite and reduce further weight loss. 
• Prednisone: Appetite stimulation is another reported use of corticosteroids which is used for presumably short-term purposes only. They are most valuable in the cases of terminal conditions to enhance the eating and the overall full of vitality of the patients. An example of correct use of steroids in a patient with a serious disease is prescribed short-term course of prednisone to the patient with the diagnosis of chronic obstructive pulmonary disease in the terminal phase – to stimulate the appetite and enhance the quality of life. 
• Mirtazapine: That is an antidepressant that is prescribed to patients who having features of loss of appetite. This is especially the case in patients who present with depression and other illness Interpersonal therapy also assumes that depression results from disturbances in social relationships. A patient with CKD also diagnosed with depression and anorexia could take mirtazapine for treatment as it has antidepressant and appetite-enhancing properties. 

Nephrology

Nutrition

• Feeding Tubes: Insertion of NG, PEG or jejunostomy to feed the patient in situations where he cannot tolerate oral feeds. 
• Parenteral Nutrition: TFP administered intravenously through a central venous catheter if there is no possibility for gastro-intestinal uptake. 
• Endoscopic/Surgical Interventions: Surgical interventions such as endoscopic dilation, stent placement, or definitive resection of obstructing GI malignancies. 
• Appetite Stimulants: Feeding the patient through enteral nutrition and providing drugs like megestrol acetate or mirtazapine to stimulate appetite. 
• Palliative Interventions: Palliative care for pain and other non-oncologic symptoms as well as psychology for all patients with compromised quality of life and other definable causes for anorexia. 
• Gastrostomy/Jejunostomy: Direct ingestion of long-term gastrostomy tubes for palliative care patients with medial conditions that need long term nutrition support. 

Nephrology

Nutrition

• Assessment: Identify features, which may be contributing to the problems, evaluate nutritional status and define signs. 
• Initial Interventions: Alteration of diet, managing of symptoms and psychosocial treatment. 
• Pharmacological Interventions: Try to enhance appetite and ensure improved nutritional status by supplementing. 
• Nutritional Support Procedures: If the patient requires enteric feeding through a nasogastric tube, an oral or other feeding route, this should be done, or if TPN should be started. 
• Advanced Interventions: There are other approaches that involve gastrointestinal issues either as an endoscopic or as surgical operations. 
• Monitoring and Adjustment: They need to document the outcome of the patients’ response to the applied interventions and consider whether any changes need to be made to the other interventions. 
• Palliative Care: As with the quality of life which is more particularly the comfort of terminal patients more attention is paid to the quality and less to the quantity of the patient’s life, terminal patients.