Loss of appetite is a common symptom observed in patients with severe illnesses \cite{Laviano_2003}. As the inflammatory response triggers cytokines that act on brain regions controlling appetite, patients often experience a poor appetite during the early stages of the disease \cite{Langhans_2000}. However, cytokine levels decrease as the patient recovers and the illness resolves, normalizing appetite. This phenomenon is often observed in hospitalized patients.
For example, during their initial admission, patients with bacterial pneumonia typically have a minimal appetite and consume only small amounts of food due to their illness. As antibiotic therapy takes effect and their pneumonia improves, they will experience a return to a normal appetite. Upon admission, a pneumonia patient initially may only desire toast for breakfast but quickly regain their energy and hunger after successful treatment, allowing them to consume a full breakfast. The hospitalist can often quickly assess a patient’s overall recovery by observing a clean plate after their meal.  
The observation that a patient's food intake increases over the course of hospitalization is a useful clinical sign for physicians. It is one objective measure that suggests the patient is responding to therapy. The clean plate sign is a quick and effective way to assess improvement in appetite and indicates that the patient may be getting well enough to be discharged from the hospital.