The changes that occur in the body weight from day to day or, indeed, from hour to hour are unnoticed by most persons, probably because the body weight is fairly constant for weeks at a time. Large losses in weight, such as those which result from extreme exercise and profuse perspiration, as in athletic contests, are easily recognized, but smaller losses or increases are not so apparent. Thus, during the day variations in body weight amounting to several pounds, directly attributable to the ingestion of food and drink and the passage of feces and urine, may not be noted because it is not the custom to record the body weight frequently throughout the day and often the appliance on which the body is weighed is not accurate enough to show changes in weight of less than 1 pound or 0.5 Kg. Such alterations in body weight are easily understood, however,