Loss of Appetite

The pleasant anticipation of eating that we call appetite is controlled by two centers in the brain : one is the hypothalamus, which stimulates the release of hunger producing hormones until hunger is satisfied ; the other is the cerebral cortex ,the center of intellectual and sensory function. Thus , a healthy appetite reflects both an unconscious response and learned  behaviour.
Many disorders and circumstances causes loss of appetite; most are temporary conditions, such a cold, an upset stomach, dental problems or stress. A persistent loss of appetite, however can reflect a more serious illness;  for example clinical depression, anemia and kidney disease, AIDS or cancer.
In usual cases, appetite loss stems from nutritional deficiencies, usually of vitamin C , thiamine, niacin , brotin and zinc. Excessive drinking of alcohol not only reduces appetite but may also ause nutritional deficiencies. Smoking is another activity that blunts appetite. To avoid all these eat snacks throughout the day rather than three big meals.