Water retention is the abnormal accumulation of fluid in the body’s tissues — the swelling of ankles, fingers, or face that dieters notice first in the mirror or the shoe. Medically it is oedema: excess fluid leaking from blood vessels into surrounding tissue. Mild cases follow salty meals, heat, long flights, or hormonal cycles and resolve on their own; persistent or severe retention signals heart, kidney, or liver disease, or the protein deficiency of kwashiorkor, and needs medical investigation. Diuretic foods and drinks are folk remedies of limited value — the effective measures are less salt, more movement, and treating the underlying cause. It is a symptom that deserves respect, not just complaint.