Both overeating and overdrinking may be (1) temporary - that is, the result of an occasional debauch; or (2) chronic.

1. Temporary overeating may apply to the excessive consumption (a) of a mixed diet, or (b) of particular articles of food. The former (a) causes dyspepsia, or, in extreme cases, acute gastro-enter-itis. The latter (b) may also cause dyspepsia and diarrhoea, or such affections may be produced as glycosuria, from excessive indulgence in candy and sweets; acne and other skin diseases, from the too liberal consumption of fats.

Temporary overeating at one or two meals may not produce any serious effect, but if the excess in feeding be long continued a variety of ills result, attributable directly to overloading of the alimentary canal and to the accumulation of waste matter in the tissues, and consequent imperfect oxidation processes.

The excess of food may be injurious in one of two ways:

First, if it is not absorbed, it ferments abnormally in the alimentary canal. There is a limit to the quantity of every food which can be digested in a given time; beyond this the food, whether starches, fats, sugars, or proteids, may decompose, or pass away unaltered.

Second, if the excess be absorbed the blood is overwhelmed, and the excretory organs are overworked.

The inability to sing with precision after a too hearty meal is often attributed to temporary congestion of the vocal cords. While this is observed in the thickened speech of alcoholism, the difficulty in singing caused by overeating is mainly due to inability to regulate the actions of the diaphragm and other respiratory muscles when the stomach is too greatly distended.

2. Chronic overeating may cause such diseases or diatheses as obesity, gout, lithaemia, oxaluria, and the formation of renal, vesical, and hepatic calculi. It is very certain to cause congestion of the liver and the condition known as " biliousness," in which the stomach and intestines are engorged, constipation results, the tongue is heavily coated, the bodily secretions are altered in composition, the urine especially becoming overloaded with salts, the liver becomes congested, and finally the nervous and muscular systems are affected, with the result of the production of headache and feelings of fatigue, lassitude, drowsiness, and mental stupor.

For persons leading sedentary lives, excessive consumption of animal food is more injurious than that of vegetable food, for the reasons given above, although obesity is more favoured by excess in vegetable diet and sweets. The nitrogenous foods, requiring, as they do, a large consumption of oxygen for their complete combustion and reduction to urea and allied products, produce forms of waste matter in the system which are more deleterious than the carbohydrates that are converted into water and carbonic acid, and are more easily eliminated. It is for this reason that defective nitrogenous metabolism alters the composition of the blood and paves the way for disorders of nutrition, such as lithiasis.

Patients suffering from severe epilepsy and from certain forms of insanity, chiefly manias, and sometimes hypochondriacs, at times gorge themselves with food and drink.

The presence of intestinal roundworms and tapeworms may give rise to overeating, though this by no means always follows.

Overeating is apt to be carried to an injurious extent by the half-starved poor if they have sudden access to plenty, and by convalescents from typhoid fever.

Bulimia is a form of perverted sensation, causing inordinate craving for food. (See p. 333).

Overeating not only taxes the digestive system, but, what is often more serious, it throws too great a strain upon the glandular and excretory organs, especially the liver and kidneys, and if the habit is long continued, disease of the nature above described inevitably results. In like manner the overfed boiler becomes sooner burned out, and its fires choked with ashes which accumulate faster than they can be removed. Overeating, especially among the well-to-do, is the commonest dietetic error, and looking at the question in its broadest aspects, it is quite certain that the foundation for more disease is laid by this habit than by overdrinking. (See Alcohol, p. 228.) The former, indeed, sometimes conduces to the latter, and there are some examples of alcoholism in which the desire for drink is only aroused and fostered by previous excesses in eating.

Overdrinking, except of alcohol (which is considered under the heading of Alcoholism), is not common, and is mainly confined to the excessive consumption of tea and coffee, which results in insomnia, cardiac palpitations, and various neuroses. Dilatation of the stomach has been attributed in some cases to overindulgence in mineral waters, but such instances are very unusual. Polyuria and diabetes insipidus have also been ascribed to the abnormal consumption of fluids, but without strong proof. Excessive use of milk as a beverage usually results in " biliousness" and constipation, but for the reason that it is really a solid food - that is, it becomes such immediately on entering the stomach. Thirst is often extreme in fevers, diabetes, and other conditions, but the drinking of exceptionally large quantities of water is by no means always harmful, and it is often desirable to recommend it as a diluent and diuretic. The propriety of restricting its use in dropsies, gastric disorders, etc., will be considered under the appropriate headings. (See Gastric Catarrh, Ascites, Diabetes).