An excessive appetite, continued hunger despite eating, and over eating (polyphagia) are actually slightly different problems, but they overlap considerably.
Pregnancy is a very normal cause of excessive hunger. In the first three or four months of pregnancy, women often eat enormous amounts of food, with minimal increase in weight, due to their increased metabolic (body chemistry) activity.
Bulimia is a psychiatric condition in which anxious patients consume excessive amounts of food, often sweets or fatty foods, and then vomit to get rid of the food and so stay slim.
The thyroid gland in the front of the neck produces the hormone thyroxine, which acts as an accelerator for every cell in the body. If there is an excess of thyroxine (hyperthyroidism), all organs will function more rapidly, and symptoms will include sweating, weight loss, diarrhoea, malabsorption, hunger, nervousness, heat intolerance, rapid heart rate, warm skin, tremor and prominent eyes.
The early symptoms of diabetes are unusual tiredness, increased thirst and hunger, excess passing of urine, weight loss despite a large food intake, itchy rashes, recurrent vaginal thrush infections, pins and needles and blurred vision.
Damage to the pituitary gland under the brain, or the part of the brain (hypothalamus) that controls it, may result in inappropriate signals being sent to the thyroid, ovaries, testes, pancreas and other glands of the body to create an excessive appetite as well as other varied symptoms.
Patients with a peptic ulcer or stomach inflammation (gastritis) will find that food eases their pain, but unfortunately the pain returns an hour or so later. As a result they may eat excessively to control their discomfort.