Constantly losing weight without trying

Many problems can cause unplanned weight loss, including changes in appetite, digestion, hormones, mood, medicines, long-term illness and cancer. The symptom alone cannot identify the cause.

Weight may fall when you eat less, cannot absorb nutrients normally, lose fluid, or use more energy because of illness. Problems with chewing or swallowing, nausea, bowel changes, pain and low mood can also reduce food intake without an intentional diet.

Several cancers can present with unexplained weight loss, but this symptom has many non-cancer causes. A clinician considers its pattern alongside appetite, examination findings, existing conditions and any other symptoms rather than interpreting weight change on its own.

Arrange a clinic appointment if the loss is continuing or has no clear explanation. Record recent weights using the same scale when practical, and note appetite, meals, swallowing difficulty, vomiting, bowel changes, cough, fever, night sweats, pain and tiredness. Bring a list of medicines and supplements.

Until you are assessed, choose foods and drinks you can tolerate and avoid forcing large meals if that worsens nausea or discomfort. A clinician may review nutrition, examine you and select tests according to the full symptom pattern.

Seek urgent medical help for weight loss accompanied by inability to keep fluids down, severe weakness, fainting, confusion, difficulty breathing, vomiting blood, black stools or heavy bleeding. These features can signal dehydration, bleeding or another problem needing prompt treatment.

Contact a clinician soon if you also have a new lump, persistent fever, drenching night sweats, ongoing pain, a lasting change in bowel habits, trouble swallowing or a cough that does not settle.

Ask which features of your history could explain the change, whether any medicine may affect appetite or digestion, what examination or tests are appropriate, and whether support from a dietitian would help while the cause is investigated.