Viral Upper Respiratory Infection (URTI): This is often the most common cause of fatigue and loss of taste, as many viruses can affect the sense of taste and smell, leading to fatigue due to the body's immune response.

Anemia: Fatigue is a hallmark symptom of anemia, and some forms can lead to changes in taste perception.
Hypothyroidism: This condition can cause fatigue and may affect taste and smell.
Zinc Deficiency: Zinc is crucial for taste function, and its deficiency can lead to impaired taste and fatigue.
Depression: While primarily a psychiatric condition, depression can manifest with physical symptoms including fatigue and changes in taste.

COVID-19: Given its global impact, COVID-19 is a critical diagnosis not to miss, as it can present with fatigue, loss of taste (ageusia), and loss of smell (anosmia).
Diabetes: Uncontrolled diabetes can lead to fatigue and may affect taste. It's crucial to diagnose and manage to prevent long-term complications.
Neurodegenerative Diseases (e.g., Alzheimer's, Parkinson's): In some cases, these diseases can present with changes in sensory perception, including taste, along with fatigue.

Multiple Sclerosis: A condition that affects the brain and spinal cord, leading to a wide range of potential symptoms, including fatigue and sensory changes.
Sjögren's Syndrome: An autoimmune disorder that can cause dry mouth and affect taste, leading to fatigue among other symptoms.
Brain Tumors: Though rare, tumors affecting the brain can lead to a variety of symptoms, including changes in taste and fatigue, depending on their location.