What could cause someone to have ketones in their urine?

Ketonuria: Ketonuria indicates that the person is in a catabolic state and is breaking down fat and can occur in anyone who has a negative caloric balance while dieting. However, in the absence of a person purposely trying to restrict calories, the presence of urine ketones along with hyperglycemia is more serious than hyperglycemia alone. Usually used to monitor for ketoacidosis in diabetics that are ill.