Of all substances in the organism, fat proves least of all a foreign body when taken in from the outer world. More readily than any other substance, it passes over from the quality it brings with it when taken as a food, to the mode of action of the human organism itself. The 80% of fat contained, for instance, in butter, passes unchanged through the domains of ptyalin and pepsin and is only transformed by the pancreatic juice into glycerine and fatty acids.
This behaviour of fat is only possible because it carries with it as little as possible of the specific nature of a foreign organism (of its etheric forces, etc.) into the human organism. The latter can easily incorporate it into its own activity.
This again is due to the fact that fat plays its part above all in the production of the inner warmth. Now the inner warmth is the element of the physical organism in which the ego organization prefers to live. Of every substance to be found in the human body, only as much is appropriate for the ego organization as gives rise to the development of warmth. By its total behaviour fat proves itself to be a substance which merely fills the body, is merely carried by the body, and is important for the active organization through those processes alone in which it engenders warmth. Derived as foodstuff, for example, from an animal source, fat will take nothing with it from the animal organism into the human, save only its inherent faculty of evolving warmth.
Now this development of warmth is one of the last processes of the metabolism. The fat received as food is therefore preserved as such throughout the first and middle processes of metabolism; its absorption only takes place in the region of the inmost activities of the body, beginning with the pancreatic fluid.
The occurrence of fat in human milk points to an exceedingly significant activity of the organism. The body does not consume this fat, it allows it to pass over into a product of secretion. Now, into this secreted fat the ego-organization also passes over. It is on this that the form-giving power of the mother's milk depends. The mother thereby transmits her own formative forces of the ego-organization to the child, and thus adds something more to the formative forces she has already transmitted by heredity.
The healthy process occurs when the human form-giving forces consume the fat store present in the body in the development of warmth. On the other hand it is unhealthy if the fat is not used up by the ego-organization in processes of warmth, but carried over, unused, into the organism. Such fat will then give rise at one point or another in the body to an excessive power of producing warmth. The warmth thus engendered will mislead other life processes by interfering in the organism here and there without being grasped by the ego-organization. There may arise what may be called parasitic foci of warmth. These bear within themselves the tendency to inflammatory conditions. The origin of such must be sought in the fact that the body develops a tendency to accumulate more fat than the ego-organization requires for its life in inner warmth.
In the healthy organism, the animal (astral) forces will produce or receive as much fat as the ego-organization is able to translate into warmth-processes and, in addition, as much as is required to keep the mechanism of muscle and bone in order. The warmth that the body needs will then be created. If the animal forces supply the ego-organization with an insufficient quantity of fat, the ego-organization will experience hunger for warmth. The necessary warmth must be withdrawn from the activities of the organs. The latter then become internally stiff and fragile. Their essential processes take place too sluggishly. We see the appearance, at one point or another, of pathological processes for an understanding of which it will be necessary to recognize if and how they are due to a general deficiency of fat.
If on the other hand, as in the case already mentioned, there is an excess of fat, giving rise to parasitic foci of warmth, organs will be taken hold of in such a way as to become active beyond their normal measure. Tendencies towards excessive nourishment will then arise, so as to overload the organism. It need not imply that the person becomes an excessive eater. It may be, for instance, that the metabolic activity of the organism supplies too much substance to an organ of the head, withdrawing it from organs of the lower body and from the secretory processes. The action of the organs thus deprived will then be lowered in vitality. The secretions of the glands, for instance, may become deficient. The fluid constituents of the organism are brought into an unhealthy relationship in their mixture. For instance, the secretion of bile may become too great compared with that of pancreatic fluid. Once again it will be important to recognize how a syndrome arising locally is to be judged in that it may proceed in one way or another from an unhealthy activity of fat.