Dr. Harvey knew that a diet of purely animal foods helped cure diabetes and would likely help obesity as well.
Mr. Harvey's Remarks
“My patient, Mr. Banting having published for the benefit of his fellow sufferers, some account of the diet which I recommended him to adopt with a view to relieve himself of a distressing degree of hypertrophy of the adipose tissue. I have been frequently urged by him to explain the principles upon which I was enable to treat with success the inconvenient and in some instances distressing condition of the system.
“The simple history of my finding occasion to investigate the subject is as follows: when in Paris in the year 1856, I took the opportunity of attending a discussion on the views of M. Bernard who was at that time propounding his now generally admitted theory of the liver functions. After he had discovered by chemical processes and physiological experiments, which it is unnecessary for me to recapitulate here, that the liver not only secreted bile, but also a peculiar amyloid or starch-like product which he called glucose, and which in its chemical and physical properties appeared to be nearly allied to saccharine matter, he further found that this glucose could be directly produced in the liver by the ingestion of sugar and its ally starch and that in diabetes it existed there in considerable excess.
It had long been well known that a purely animal diet greatly assisted in checking die secretion of diabetic urine; and it seemed to follow, as a matter of course, that the total abstinence from saccharine and farinaceous matter must drain the liver of this excessive amount of glucose, aid thus arrest in a similar proportion the diabetic tendency. Reflecting on this chain of argument and knowing too that a saccharine and farinaceous diet is used to fatten certain animals and that in diabetes, the whole of the fat in the body rapidly disappears, it occurred to me that excessive obesity might be allied to diabetes as to its cause, although widely diverse in its development: and that if a purely animal diet was useful in the latter disease, a combination of animal food with such vegetable matter as contained neither sugar nor starch, might serve to arrest the undue formation of fat.
I soon afterwards had an opportunity of testing this idea. A dispensary patient who consulted me for deafness, and who was enourmously corpulent, I found to have no distinguishable disease of the ear. I therefore suspected that his deafness arose from the great development of adipose matter in the throat, pressing upon and stopping up the eustachian tubes. I subjected him to a strict non-farinaceous and non-saccharine diet, and treated him with the volatile alkali alluded to in his Pamphlet, and occasional aperients and in about seven months he was reduced to almost normal proportions, his hearing restored and his general health immensely improved. The case seemed to give substance and reality to my conjectures, which further experience has confirmed.
“When we consider that fat is what is termed hydrocarbon, and deposits itself so insidiously and yet so gradually amongst the tissues of the body it is at once manifest that we require such substances as contain a superfluity of oxygen and nitrogen to arrest its formation and to vitalize the system. That is the principle upon which the diet suggested in his pamphlet works, and explains on the one hand the necessity of abstaining from all vegetable roots which hold a large quantity of saccharine matter, and on the other beneficial effects derivable from those vegetables, the fruits of which are on the exterior of the earth, as they lose, probably by means of the sun’s action a large proportion of their sugar.
“With regard to the tables of Dr. Hutchinson, referred to in his Pamphlet, it is no doubt difficult, as he says, to determine what is a man’s proper weight, which must be influenced by various cases. Those tables, however, were formed by him on the principle of considering the amount of air which the lungs in their healthy state can receive and apply to the oxidation of the blood. I gave them to Mr. Banting as an indication only of what the approximate weight of persons in proportion to their stature should be, and with the view of proving to them the importance of keeping down the tendency to grow fat; for, as that tendency increases, the capacity of the lungs, and consequently the vitality and power of the whole system must diminish. In conclusion, I would suggest the propriety of advising a dietary such as this in diseases that are in any way influenced by a disordered condition of the hepatic functions as they cannot fail to yield in some degree to this simple method of treatment if fairly and properly carried out; it remains for me to watch its progress in a more limited sphere.
WILLIAM HARVEY, F.R.C.S.
Surgeon to the Royal Dispensary for Diseases of the Ear 2, Soho Square