Significant unintentional weight loss: what to know

Unintentional weight loss means losing weight without deliberately changing food intake or exercise. It may follow reduced appetite, dental or swallowing problems, nausea, diarrhoea, or difficulty absorbing nutrients. Some people lose weight while eating normally because their body is using energy differently.

Possible underlying conditions include coeliac disease, Crohn's disease, hyperthyroidism, diabetes, tuberculosis, HIV infection, and depression. These conditions have different patterns and treatments; weight loss alone cannot identify the cause. Note changes in thirst, urination, bowel habits, mood, sleep, fever, cough, pain, or energy.

Arrange an appointment with a doctor if the loss is ongoing, noticeable, or unexplained. Before the visit, record when it began, any recent weights, appetite and typical meals, medicines or supplements, bowel symptoms, and other changes. Do not start restrictive diets or use weight-gain products without advice. Regular fluids and nourishing meals may help while you arrange assessment, unless eating or drinking worsens symptoms.

Seek urgent medical help for weight loss with severe weakness, confusion, fainting, difficulty breathing, chest pain, persistent vomiting, inability to keep fluids down, or signs of severe dehydration. Prompt assessment is also appropriate for weight loss with coughing blood, black or bloody stools, a persistent fever, or rapidly worsening symptoms.

Ask what could explain the change, which examination or tests may be useful, and whether any medicine could be affecting appetite or digestion. Tell the doctor about intentional dietary changes, stress, low mood, recent travel, contact with illness, and family health conditions. Ask which symptoms should prompt an earlier review and how to support nutrition safely.