~Causes of Obesity.~--It is stated that at least fifty per cent. of the obesity is of hereditary origin, while the rest may be due to overeating and drinking, unbalanced diets, metabolic changes due to the approach of menopause in women, and diseases such as gout in which there is a certain amount of disturbance in the blood and excretory organs and in which the diet or the disease may be accountable for the gain of surplus adipose tissue. Women approaching menopause may not change their diet in the least and there may still be the noticeable increase of fat. ~Obesity Cures.~--A great number of the "cures" are undertaken not from a health standpoint but from the esthetic point entirely. It makes no difference what reason is brought forward for instituting the treatment, it is the results which count. Of the cures undertaken which are in themselves good, but which are too strenuous for the average "fat person" to stick to may be mentioned some of the early cures instituted and recommended by Banting, Oertel, and Ebstein. Obesity, then, may be said to be due to (1) heredity, (2) overeating and drinking, (3) lack of exercise (sedentary life), (4) a combination of the above causes. Whether the obesity is due to the lack of exercise or the lack of exercise is due to the accumulation of fat which causes a disinclination to move on the part of the individual, can only be judged when a thorough examination into the life and habits of the patient is made. ~Comparison of Food Intake and Energy Output.~--Many fat people who claim to be small eaters in reality constantly consume more food than their age, weight, or mode of living would necessitate. If such patients could be prevailed upon to keep a correct chart of their daily intake of food and the amount of exercise taken, they would be astounded to find how much greater was the intake in comparison to the output of energy, in other words, how much more food they ate than they required to keep them in health. A glance at the first tables in this text will show which foods are utilized by the body chiefly as a source of energy. ~Uses of Food in Body.~--Physiological chemistry proves that when more food is taken than is needed for the internal and external work of the body, the surplus is stored for future use, first, in the liver and muscles as glycogen for the general expenditures, and, second, as adipose tissue for future use. Thus it is seen that when the intake is constantly greater than the energy expenditure there must necessarily be some way in which the body can store up the surplus fuel, and so long as the digestion remains good and the amount of exercise limited there is no reason why there should not be a constant and steady accumulation of surplus fat which inevitably terminates in obesity.