Though the student may be normal and healthy, it is possible to make many valuable experiments in regard to special adaptations of diet, such as combinations to induce natural sleep; to produce and to relieve constipation and diarrhea; to produce excessive body-heat when exposed to cold, or the minimum of heat in summer, or in warm climates. VALUE OF DIAGNOSIS Correct diagnosis is one of the most important factors in the practise of applied food chemistry, and when a correct diagnosis has been made the remedy will suggest itself if the student has a thorough understanding of causes. [Sidenote: Causes sometimes very remote] In diagnosis it is often necessary to ascertain the patient's general habits of eating during the few years prior to the appearance of the disorders. As an example, rheumatic conditions are often superinduced by an overconsumption of starch, usually cereal starch and acids. This overindulgence may have continued for several years before the appearance of any rheumatic symptoms. The primary causes being residual in the body, exposure, low vitality, or extreme climatic changes may give expression to them in the form of rheumatism, or some kindred trouble. [Sidenote: Value of limited feeding] After determining the causes, a diet should be designed which will counteract existing conditions. This may usually be accomplished by limiting the quantity of food somewhat below the demands of normal hunger. This will give the digestive organs less work to do, and the body an opportunity to take up or consume any excess of food matter that may have become congested. In cases accompanied by loss of hunger, it is sometimes necessary to put the patient upon an absolute fast from one to three days, but in the majority of cases a semi-fast is best, prescribing light, nutritious foods of a remedial character. EDUCATE YOUR PATIENT In beginning treatment each patient should be made acquainted with the fact that the radical change in diet may bring slight discomfort. While the system is adjusting itself to the new regimen, there is usually a slight loss of weight and a feeling of weakness or lassitude. [Sidenote: Curing a slow process] It should be impressed upon the mind of the patient that regaining health and strength is in reality a process of growth or evolution, hence slow and gradual; that when one has violated the laws of health for many years, Nature will not, or probably cannot forgive all these sins and repair all these wrongs in a month or two. However, when one gets in harmony with the physical universe, and conforms to the laws of his organization, Nature will construct (cure) much more rapidly than she formerly destroyed (produced dis-ease). [Sidenote: The patient should agree with the diet]