A study of prolonged fasting / by Francis Gano Benedict.

  • Benedict, Francis Gano, 1870-1957.
Date:
1915
Catalogue details

Licence: Public Domain Mark

Credit: A study of prolonged fasting / by Francis Gano Benedict. Source: Wellcome Collection.

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    The average normal man represents the mean between the two extremes of the emaciated, half-starved individual, disinclined to phys- ical or mental work, and the over-fed, obese epicure, both extremes being relatively low in vital activity and in productivity. Further- more, if we consider the metabolism under pathological conditions, we find even greater variations in the different levels of vital activity. Thus a sick person, much emaciated, lying in bed without food, and with subnormal temperature, has unquestionably a low cellular activity. On the other hand, a sick person with a high fever, even when asleep and without extraneous muscular activity, may have a greatly increased cellular activity. It will be seen, therefore, that from the standpoint of both normal physiology and pathology, a study of human individuals under different conditions and with different planes of activity is of fundamental importance. For such study it is essential to determine the basal or fundamental metabolism, when the activities are on a low plane, to be used as a basis of comparison with other values. We may ask, then, ‘‘What is the lowest plane of vital activity which is compatible with life?”? Unques- tionably there have been severe pathological cases, with emaciation and muscular atrophy, in which life has been maintained at a plane far below that which can be reached by the average normal man, but it has been the prime object of most investigators in metabolism to concen- trate their efforts upon securing, with normal individuals, physiological values which may withstand criticism, since these constitute the only - true basis of comparison. Taking into consideration the influence upon metabolism of muscular activity, of the ingestion of food, and the state of being awake, we may assert that the lowest metabolic plane would be found for an individual during deep sleep in bed, with complete muscular repose, and without food in the alimentary tract. As a matter of fact, with most people such a condition is usually closely approximated each day about 4 a. m. While in general no food is taken by an individual for about 10 or 12 hours during the night, yet for a considerable period of time after the evening meal nutrients are being absorbed from the ingested food mate- rials and carried to different parts of the body, there to be oxidized or deposited. It is furthermore true that certain molecular fragments, probably acid in nature, may be absorbed from the food materials which, when carried to the various parts of the body, may actually stimulate metabolism to a greater intensity, these being the so-called katabolic stimuli. Usually the influence of the ingestion of food ceases from 6 to 8 or 10 hours after the meal, particularly if the food ingested is not protein-rich. Accordingly, for one or two hours prior to rising in the morning the normal man is probably living at his lowest metabolic plane.