Fatigue and weight loss: what to know

Weight may fall when appetite is low, eating is difficult, or the body is using more energy during illness. Fatigue can accompany poor sleep, emotional strain, infection, anaemia, or problems involving the kidneys or digestion. Coeliac disease can interfere with nutrient absorption, while alcohol use may affect appetite, sleep, and general health. These symptoms do not identify one diagnosis on their own.

Arrange a primary-care appointment if the change is unplanned, continues, or is affecting daily activities. Note when tiredness began, how your weight has changed, appetite, thirst, bowel changes, fever, sleep, medicines, and alcohol intake. Keep meals simple and nourishing, drink regularly, and avoid strenuous activity if you feel faint. A clinician may examine you and decide whether blood or other tests are appropriate.

Seek urgent help for severe weakness, fainting, confusion, inability to keep fluids down, black or bloody stools, chest pain, or difficulty breathing. Contact a clinician soon if weight loss is continuing, fatigue is rapidly worsening, or you have persistent fever, night sweats, marked thirst, or a major change in bowel habits.

Could my symptoms be related to appetite, digestion, blood counts, sleep, medicines, or another illness? Which changes should I track? What tests might help explain the weight loss and fatigue?