Hyperthyroidism

Unintentional weight loss exceeding 5% of body weight over 6–12 months, or any unexplained rapid loss, requires medical investigation. Common causes include hyperthyroidism, type 2 diabetes, coeliac disease, IBD, depression, and malignancy. NICE guidelines define the investigation pathway. This article covers what to look for and when to contact a GP.

Losing weight without trying — particularly 5% or more body weight in 6 months — is a clinical red flag requiring GP assessment. Cancer is one of multiple possible causes. This article covers what weight of loss is medically significant, the full differential diagnosis, when to seek urgent versus routine care, and what investigations to expect.