Once this trail was opened, further observations seemed to fall into line. It is, for instance, well known that during pregnancy an obese woman can very easily lose weight. She can drastically reduce her diet without feeling hunger or discomfort and lose weight without in any way harming the child in her womb. It is also surprising to what extent a woman can suffer from pregnancy-vomiting without coming to any real harm.
Pregnancy is an obese woman's one great chance to reduce her excess weight. That she so rarely makes use of this opportunity is due to the erroneous notion, usually fostered by her elder relations, that she now has “two mouths to feed” and must “keep up her strength for the coming event. All modern obstetricians know that this is nonsense and that the more superfluous fat is lost the less difficult will be the confinement, though some still hesitate to prescribe a diet sufficiently low in Calories to bring about a drastic reduction.
A woman may gain weight during pregnancy, but she never becomes obese in the strict sense of the word. Under the influence of the HCG which circulates in enormous quantities in her body during pregnancy, her diencephalic banking capacity seems to be unlimited, and abnormal fixed deposits are never formed. At confinement she is suddenly deprived of HCG, and her diencephalic fat-center reverts to its normal capacity. It is only then that the abnormally accumulated fat is locked away again in a fixed deposit. From that moment on she is suffering from obesity and is subject to all its consequences.
Pregnancy seems to be the only normal human condition in which the diencephalic fat-banking capacity is unlimited. It is only during pregnancy that fixed fat deposits can be transferred back into the normal current account and freely drawn upon to make up for any nutritional deficit. During pregnancy, every ounce of reserve fat is placed at the disposal of the growing fetus. Were this not so, an obese woman, whose normal reserves are already depleted, would have the greatest difficulties in bringing her pregnancy to full term. There is considerable evidence to suggest that it is the HCG produced in large quantities in the placenta which brings about this diencephalic change.
Though we may be able to increase the dieneephalic fat banking capacity by injecting HCG, this does not in itself affect the weight, just as transferring monetary funds from a fixed deposit into a current account does not make a man any poorer; to become poorer it is also necessary that he freely spends the money which thus becomes available. In pregnancy the needs of the growing embryo take care of this to some extent, but in the treatment of obesity there is no embryo, and so a very severe dietary restriction must take its place for the duration of treatment.
Only when the fat which is in transit under the effect of HCG is actually consumed can more fat be withdrawn from the fixed deposits. In pregnancy it would be most undesirable if the fetus were offered ample food only when there is a high influx from the intestinal tract. Ideal nutritional conditions for the fetus can only be achieved when the mother's blood is continually saturated with food, regardless of whether she eats or not, as otherwise a period of starvation might hamper the steady growth of the embryo. It seems that HCG brings about this continual saturation of the blood, which is the reason why obese patients under treatment with HCG never feel hungry in spite of their drastically reduced food intake.