What should you know about unexplained weight loss and loss of appetite?

Reduced appetite may follow stress, low mood, pain, nausea, changes in taste, or a medicine. Weight loss can also accompany coeliac disease, Crohn's disease, hyperthyroidism, type 1 diabetes, type 2 diabetes, tuberculosis, or HIV infection. Depression may reduce interest in food and daily activities. These conditions differ widely, and weight loss does not by itself show which one is present. Your starting weight, eating pattern, bowel symptoms, thirst, urination, fever, and mood all help a clinician interpret the change.

Book a primary-care appointment and bring a list of medicines, supplements, recent illnesses, dietary changes, and any digestive or emotional symptoms. If eating feels difficult, try small regular meals and nourishing fluids that you tolerate, while continuing to drink enough. Do not rely on supplements as a substitute for assessment. A clinician may examine you and decide whether blood tests, urine tests, or other investigations are appropriate.

Seek urgent care for inability to keep fluids down, severe weakness, confusion, fainting, signs of dehydration, severe abdominal pain, vomiting blood, black stool, or new breathing difficulty. Rapid deterioration, marked thirst with frequent urination, or weight loss with fever and feeling very unwell also needs prompt assessment.

What could explain both the appetite change and weight loss? Could my medicines, mood, thyroid, blood sugar, digestion, or an infection be involved? Which tests are suitable? How can I maintain nutrition while this is investigated?