There is no doubt that in spite of the controlling influence of diet, some persons have a tendency to grow fat, and that others either become or remain thin. It is more difficult to make a person thin by nature grow fat, than to reduce a fat person. The articles of food - the butter, cream, puddings, and sweets - which are eliminated from the dietary of the fat, may be greatly increased in the dietary of the thin, often without making any marked difference in their condition and weight. By a strange perversity of nature also the thin person frequently dislikes the food that would make him grow fat. It is probable, moreover, that the greater activity of the spare body keeps it thin.

When, however, thinness becomes progressive, and approaches emaciation, and is moreover associated with anaemia, weakness, and that group of nervous symptoms known under the name of hysteria, it may be very successfully treated as a symptom of a disease of nutrition.