Sudden unintentional weight loss: what to know

Weight may fall when appetite is reduced, eating becomes difficult, or the body cannot absorb nutrients well. Stress, low mood, dental problems, medication effects, and changes in routine can all affect intake. Digestive conditions such as Coeliac Disease or Crohn's Disease may interfere with absorption. An overactive thyroid, diabetes, long-term infection, or another health problem can also alter how the body uses energy. Weight loss alone does not identify one cause.

Arrange a medical appointment if the loss is continuing, unexplained, or accompanied by appetite change, diarrhoea, pain, thirst, frequent urination, fever, cough, or low mood. Before the visit, note when it began, changes in meals, exercise, medicines, bowel habits, and any other symptoms. Keep regular fluids and nourishing meals if you can, but do not start restrictive diets or supplements to mask the pattern. A clinician may review your history, examine you, and choose tests based on what they find.

Seek urgent medical help for confusion, fainting, severe weakness, inability to keep fluids down, breathing difficulty, severe abdominal pain, blood in vomit or stool, or a very high fever. Prompt assessment is also needed if weight loss occurs with marked thirst and frequent urination, or with a persistent cough and night sweats. These symptoms can signal dehydration, a serious infection, or a metabolic problem.

Ask what causes fit your symptoms, whether your medicines or mood could affect appetite, which examinations or blood tests may help, and how to monitor your weight and nutrition safely.