The effectiveness of high-fat, low-carbohydrate diets in obesity will continue to be surprising so long as people continue to regard body fat as an inert slab of suet stored round the hips and in the other fat depots.
The fatty tissues of the body are not inert at all. Together they make up a highly active organ — the "fat organ"— with definite functions comparable to those of the liver.
This "fat organ" is concerned especially with the energy needs of the body.
It shrinks under conditions of low food intake and increases when intake is high.
From this most people assume that the fat organ is simply a passive calorie store.
But this assumption is wrong. The fat organ is not passive. It has a rich blood supply and is in a constant state of activity entering into minute-to-minute metabolic changes throughout the body.
This activity can be increased or decreased by many factors, particularly by the kind of food we eat. Carbohydrate (starch and sugar) is the forerunner of excess fat in the fat organ.
On a diet devoid of carbohydrate, there is little stimulus to the "fat organ" to make extra fat. It is doubtful, in fact, whether fat in the diet can add to the weight of the "fat organ," except during recovery from starvation.
On the contrary it seems that a high fat intake depresses the manufacture of fat in the body, while increasing its utilisation as fuel.
In other words — and this is the key to Banting and all slimming — the fatty tissues can only become overweight through making fat from carbohydrate.
These statements are based on experimental work begun by Hausberger and Milstein in the Departments of Anatomy and Biochemistry at the Jefferson Medical College, Philadelphia.
They reported their findings in the Journal of Biological Chemistry, in 1955, as follows:
"Fasting or feeding a high-fat diet abolished lipogenesis (fat formation) in adipose tissue and reduced glucose oxidation markedly lipogenesis increased to the highest levels on a high-carbohydrate, fat-free diet."
They found also that in the experimental animals (rats) with which they were working, fat formation took place mainly in the adipose tissues. Massoro in Boston and Mayer and Silides at Harvard have confirmed these findings, working with tissue slices. More recent work on human subjects seems to show that these observations are also true for man.
Utilisation of radio-glucose (glucose "tagged" with radioactivity so that its metabolism can be followed) by adipose tissue has been investigated under various nutritional conditions. Fasting or feeding a high-fat diet has been found to diminish the formation of fat from carbohydrate.
Stop eating carbohydrate and eat fat instead and you will not only stop getting fat, but will get thinner.
So far so good. But here objections crop up.
These seem to be reasonable objections, yet when we come to examine them, we find that history, anthropology and the highest medical and scientific opinion have refuted them.
1. High-fat diets are nauseating and make you bilious. No one could stick to such a diet for long.
It is true that there are some people who suffer from complaints which make them unable to eat much fat. Gall bladder disease, by interfering with the flow of bile (necessary for the digestion of fat), is the best-known example. Steatorrhoea, another disease where the gut cannot digest fat, also requires a low-fat diet. But these are diseases and the Eat-Fat-Grow-Slim diet is not for people who are ill. It is for overweight adults who are healthy apart from their obesity.
First, then, what do we mean by a high-fat diet?
For the purpose of this book, it means a diet in which the calories are derived mainly from fat and, if not from fat, from protein.
Most people who eat meat consume about three parts of lean to one part of fat because that is the palatable proportion. This means that people who live exclusively on meat, derive about 80% of their calories from fat and the remaining 20% from lean, because fat is a very much more concentrated source of heat and energy than lean. Carbohydrate, as the glycogen contained in meat, would amount to ½% of the calories.
In round figures the amount of food consumed would be from 6 to 9 ounces of lean meat and 2 to 3 ounces of fat, cooked weight, at each of the three meals of the day.
Obviously, then, the people to study when we wish to investigate the idea that high-fat diets are nauseating and cannot be kept to for long, are those who eat nothing but meat.
There are many such people, but let us take the Eskimos first because nearly everybody knows, or thinks they know, something about them.
The greatest living authority on the Eskimo is Dr. Vilhjalmur Stefansson, the distinguished anthropologist and explorer. In 1906, Stefausson revolutionised polar exploration by crossing the Arctic continent alone, living "off the country" on a diet composed only of meat and fish, travelling exactly as the Eskimos did.
Not only did he remain in good health, but he enjoyed his food, ate as much as ever he wanted and did not put on weight.
More important from the slimming point of view, he never saw a fat Eskimo. Here is what he says:
"Eskimos, when still on their home meats, are never corpulent — at least, I have seen none who were. Eskimos in their native garments do give the impression of fat, round faces on fat, round bodies, but the roundness of face is a racial peculiarity and the rest of the effect is produced by loose and puffy garments. See them stripped, and one does not find the abdominal protuberances and folds which are so in evidence on Coney Island beaches and so persuasive against nudism.
There is, however, among Eskimos no racial immunity to corpulence. That is proved by the rapidity with which and the extent to which they fatten on European diets."
In other words, Eskimos stay slim on a high-fat diet, but as soon as they start eating starch and sugar they get fat.
The European brings obesity to the Eskimo in addition to his other "gifts" of civilisation.
So much for Eskimos who have never lived on anything but fat and protein. What about people who go on to an all-meat diet after they have been used to an ordinary mixed diet of cereals, sugar, vegetables, etc., as well as meat?
The key word here is pemmican, the most concentrated food known to man. It is made from lean meat, dried and pounded fine and then mixed with melted fat. It contains nothing else.
It was originally the food of the North American Indian and, by adopting it, the early fur traders and pioneers were able to perform fantastic feats of endurance.
Pemmican has been called the bread of the wilderness, but this is a romantic not a scientific description. Real pemmican is half dried lean meat and half rendered fat, by weight.
A man working hard all day on a meat diet needs a ration of six to seven pounds of fresh lean meat and a pound of fat.
Most authorities agree that this is equivalent to 2 lb. of pemmican and on this ration David Thompson, the British explorer, tells us in the Narrative of his Explorations in Western America 1784-1812 that men could slave at the hardest labour fourteen and sixteen hours a day, often in sweltering heat, as when paddling canoes up swift rivers and carrying their loads on their shoulders across portages (up beside rapids and over steep escarpments.)
What happens when a European first eats pemmican? Does it make him sick? Can he eat enough of it to keep himself going?
George Monro Grant, D.D., LL.D. (1835-1902), in his book Ocean to Ocean, published in 1873, describes his experience as secretary to Sir Sanford Fleming, on an overland expedition from Toronto to the Pacific doing preliminary work for the extension of the Canadian Pacific Railway.
Dr. Grant was educated at Glasgow University and was ordained a Minister of the Church of Scotland. From 1877- 1902 he was Principal of Queen's University, Ontario, where he gained a great reputation in education and politics. His personal experience of pemmican lasted not more than five weeks, but on the journey he travelled with a number of Europeans who had used it much longer.
The main value of Grant's observations is that they were made at the time, in diary form, not in retrospect. On page 24 of the London, 1877, edition he says:
"Our notes are presented to the public and are given almost as they were written so that others might see, as far as possible, a photograph of what we saw and thought from day to day."
After leaving Fort Carlton on their way up the North Saskatchewan to Edmonton, Grant's entry for August 19th, 1872, says:
"Terry gave us pemmican for breakfast, and, from this date, pemmican was the staple of each meal. Though none of us cared for it raw at first, we all liked it hot....
Pemmican and sun-dried thin flitches of buffalo meat are the great food staples of the plains, so much so that when you hear people speak of provisions, you may be sure that they simply mean buffalo meat, either dried or as pemmican.
August 22; At the camp, the Chief treated them with great civility, ordering pemmican, as they preferred it to fresh buffalo.
August 26: Camped before sunset within twenty- seven miles of Edmonton, and in honour of the event brought out our only bottle of claret. As we had no ice, Terry shouted to Souzie to bring some cold water, but no Souzie appearing he varied the call to 'Pemmican.' This brought Souzie, but great was his indignation when a bucket was put into his hands, instead of the rich pemmican he was never tired of feasting on.
On 31st August they left Edmonton and headed west for Jasper House. On 6th September they
"halted for dinner at the bend of the river, having travelled nine or ten miles, Frank promising us some fish, from a trouty looking stream hard by, as a change from the everlasting pemmican.
Not that anyone was tired of pemmican. All joined in its praises as the right food for a journey, and wondered why the Government had never used it in war time . . . As an army marches on its stomach, condensed food is an important object for the commissariat to consider, especially when, as in the case of the British Army, long expeditions are frequently necessary.
Pemmican is good and palatable uncooked and cooked ... It has numerous other recommendations for campaign diet. It keeps sound for twenty or thirty years, is wholesome and strengthening, portable, and needs no medicine to correct a tri-daily use of it."
In case anyone should think that these references are too old to be applicable to-day, I should like to introduce a bit of personal testimony here.
While writing this book I lived on a high-fat, high protein diet for three weeks, eating as little carbohydrate as possible. I should add that I did not sit in front of a typewriter all the time, but ran my practice and worked in the garden whenever I could because it was spring and a lot of planting had to be done.
My diet was as follows:
|Breakfast:||Fresh orange juice or 1/2 grapefruit Fried egg and bacon or fried kidneys and bacon or scrambled egg made with a lot of butter. Coffee and top milk or cream, no sugar|
|Lunch:||Steak, with fat, fried in butter Green salad with oil dressing, or green peas (frozen) and butter Water or dry red wine Cheese — preferably high-fat type e.g. Camembert, Danish blue — Apple Coffee and cream|
|Tea:||1/4 jar peanut butter, eaten with spoon. Tea with dash of milk|
|Supper:||Meat or fish, fried Salad or green vegetable Cheese, Water or dry wine|
|Nightcap:||Cup of hot milk|
I took no bread, no biscuits, no sugar, nothing between meals except a few nuts or a bit of cheese. On this diet, which I enjoyed eating and which never left me feeling hungry, I lost 3 lb. in three weeks, dropping from 11 stone 10 lb. in my clothes to 11 stone 7 lb. I was not trying to slim, only to see if I could live comfortably on it and stay fit. I am 5 feet 8 inches tall and, though not obese, I am a Fatten-Easily and have, in the past, been up to 12 ½ stone and felt uncomfortable at that weight.
Notice that I paid no attention to calories and ate as much as I felt like of the low-carbohydrate foods allowed. I also drank as much water or dry wine as I wanted. I felt well all the time and got through my work without undue effort.
I now stick to a low-carbohydrate diet of this kind from choice, because it gives me more energy than an ordinary high-starch diet and because I like it.
During the first week on this diet, my wife complained that I was bad-tempered. This I think was due to a mild ketosis which takes about a week to get used to.
Ketosis is explained under objection No. 2.
It is surprising how many authorities subscribe to the view that high-fat diets are unpalatable. It must be because they have never actually eaten them. Dr. John Clyde, who approves of high-fat diets otherwise, says in his "Family Doctor" booklet Slim Safely:
"Even with the same number of calories, the high-fat diet results in more and easier weight loss than the high-carbohydrate diet. Ideally, then, one might look for a diet containing mostly protein and fat and almost no carbohydrate. But in fact such a diet is so very different from our normal pattern of eating that I doubt whether anyone would manage to stick to it for more than a few days — which is not long enough." (My italics.)
Dr. John Clyde is a pseudonym, so it has not been possible to obtain from him the evidence on which he has based this statement, but he is not supported by others who should know. Professor Kekwick, who has been using high-fat diets for weight reduction in his patients since 1952, has kindly allowed me to quote the following case which was under his care in the Medical Unit at the Middlesex Hospital. This man was 46 years of age on admission in 1952 weighing 20 stone 12 lb. with a height of feet 6 inches. His blood pressure was high. After a period of stabilisation in the ward, he was put on a 1,000 calorie low-carbohydrate diet and in a week lost 8 lb. He was then placed on the high-fat high-calorie diet and lost a further 4 lb. during seven days. On reducing the calorie content of this type of diet to 1,000 calories, he lost another 8 lb. in the next week. He felt very well all along and not particularly hungry. He was sent home on this high-fat diet.
In February, 1953, his weight was down to 16 stone 5 lb., by April, 1953, it was 14 stone 10 lb. and, when seen in October, 1953, he weighed 11 stone 12 lb. and felt much fitter. His blood pressure was now normal. At this stage, he was taken off his diet and allowed to eat carbohydrate again. In August, 1956, his weight had increased to 14 stone 7 lb. and his blood pressure had risen again. He stated that he wished to go back to the high-fat diet as he felt better on it.
The surprising thing about a high-fat diet is that, contrary to what Dr. Clyde says, it is easy to stick to. I have tried it myself and I am convinced of this. So are some of my patients who have lost weight on it.
Nearly all those who have been on such a diet agree that it is palatable and many, like Professor Kekwick's patient, ask to go back on it when they find themselves starting to regain weight through returning to a mixed diet containing a normal proportion of carbohydrate.
In Appendix D the composition of Professor Kekwick's experimental low-calorie high-fat diets is given. It is important to realise that this high-fat diet was designed for people who were really obese. It is not for those who merely wish to lose a few pounds gained through over eating. For such people, it is only necessary to reduce the proportion of carbohydrate in their normal diet by a half to two-thirds, for weight reduction to occur.
2. High-fat diets cause ketosis and make you ill
Ketosis is a condition in which ketones (chemicals related to acetone) appear in the blood, and in the urine.
They are produced during the oxidation of fat and are made in large quantities in the untreated diabetic who, because he is unable to deal with sugar, attempts to burn fat at a great rate and in so doing makes an excess of ketones.
They accumulate to the point where they are poisonous, and in severe diabetic ketosis, coma will supervene unless insulin is given to enable the patient to utilise sugar.
But in diabetic ketosis, the level of ketones in the blood is very high. It may reach over 300 milligrams per 100c.c., 30 times higher than the moderate ketosis induced in the obese by fat feeding, which in turn is only half the moderate level of ketosis found in a normal person who has been fasting for two days.
Kekwick and Pawan in their studies on human subjects found that very high fat diets were well tolerated and that ketosis was not a complication in their obese patients.
So there are degrees of ketosis and the effects of the severe ketosis of diabetes are quite different from the mild ketosis of a fasting person or the even milder ketosis of a person on a high-fat diet.
All degrees of ketosis have one thing in common, however. They are caused by the same thing: deprivation of carbohydrate.
It is still very widely believed, by doctors as well as dieticians, that the ketosis produced by a high-fat diet is harmful, and that fats can only be utilised properly by the body in the presence of carbohydrate.
This has been expressed, in a catch phrase for medical students as, "Fat burns only in the flame of carbohydrates." In other words, if you eat a lot of fat you must also eat a lot of carbohydrate or you will not be able to use up the fat and will develop "harmful" ketosis.
Dr. Alan Porter in his "Family Doctor" booklet, Feeding the Family, published by the B.M.A., says:
"Fat is burned down by the body to carbon dioxide and water, but to do this, there must be carbohydrates present. Otherwise, the breakdown is not complete and what are called ketone bodies pass into the blood and urine. This causes sweetish breath and biliousness."
Anyone who has studied the history of diet must view this statement with scepticism. For long periods and in many places man has subsisted on an exclusive diet of fat meat. Before the discovery of agriculture, when all food had to be obtained from animal sources by hunting, man had to live on fat and protein alone, and in more recent times there is plenty of evidence that people remain healthy on an exclusive diet of meat with no carbohydrate except the tiny amount contained in the lean.
In pemmican, fat represents 75% to 80% of the available energy so that if fat really only burns in the flame of carbohydrate, anyone living exclusively on pemmican must be getting only 20-25% of the energy value out of his food. Yet this was the diet which enabled the white man to open up Western Canada and the United States!
In this connection it is interesting to note that in the backroom battles which were waged between the advocates and the opponents of pemmican as a ration for the Allied armies in the Second World War, "fat burns only" was one of the arguments used by the "experts" who succeeded in keeping pemmican out of the rations of our shock troops.
So much for the mythical dangers of ketosis on a high-fat diet in obesity.
What about the possible advantages of ketosis to the obese? Since the war these have become clearer and it now seems that the benign ketosis which develops when carbohydrates are in short supply, increases the mobilisation of stored body fat for fuel, and assists weight loss in the obese.
Further than this, it is now thought that
"unless low-calorie diets are ketogenic (have a high-fat content and give rise to ketosis) they cannot operate by increasing the use of fat by the body but only by decreasing the formation of new fat."
I quote from Dr. Alfred Pennington's address to the 11th annual New England Post-graduate Assembly, Boston, Mass., 29th October, 1952, entitled "A Reorientation on Obesity."
3. High-fat diets may be all right in the cold weather, but they are too heating in hot weather.
This popular fallacy is closely related to another one: that Eskimos eat a lot of fat in order to keep warm.
Many people are surprised to learn that Eskimos spend the time in their houses naked or almost naked, and that their outdoor clothes are so well designed that even in a temperature of minus 40° F. an Eskimo feels warmer than an Englishman in London on a January day.
To quote again from Dr. Stefansson's book, The Fat of the Land:
"... the clothes the Eskimos wear in the Arctic during the coldest month of the year, January or February, weigh under ten pounds, which is a good deal less than the winter equipment of the average New York business man. These clothes are soft as velvet, and it is only a slight exaggeration to say that the wearers have to use a test to find out whether the day is cold. At minus 40° F., a Mackenzie Eskimo, or a white man dressed in their style, sits outdoors and chats almost as comfortably as one does in a thermostat-regulated room. The cold, about which the polar explorer can read upon the scale of his thermometer, will touch only those parts of his body which are exposed, the face and the inside of the breathing apparatus, a small fraction of the body, needing little fuel for counterbalance. Warm and completely protected elsewhere, he can sit comfortably even with bare hands. Indeed, the ears, particularly liable to frost, seem to be about the only parts likely to freeze if exposed at 40° below zero while most of the rest of the body is warm...
The houses of Mackenzie River, typical in their warmth of the dwellings of most Eskimos, have frames of wood, with a covering of earth so thick that, prac tically speaking, no chill enters except its planned ventilation, for which a diving-bell principle of control is used. A room filled with warm air can lose no great amount of it through an opening in the floor, while the cold air below that opening is not able to rise into the house appreciably faster than the warm air escapes at the top.
The roof ventilator of a dwelling that shelters twenty or thirty people is likely to resemble our stove-pipes in diameter...
Through this diving-bell control of ventilation there develop several temperature levels within the house, or rather an upward graduation of warmth. Lying on the floor you might be cool at 60° sitting on the floor, the upper part of your body would be warmish at 70° or 80° sitting in the bed platform three feet above the floor you could reach up with your hand to a temperature of 90° or 100° These temperatures, in the Mackenzie district and in many other places, are produced by lamps which burn animal fat, odourless, smokeless and giving a soft, yellowish light.
During my first Mackenzie winter . . . there were enough lamps extinguished at bedtime, say 10 o'clock, to bring the room temperature down to 50° or 60°. Both sexes and all ages slept completely naked, or under light robes.
While indoors we were living in a humid, tropical environment; when outdoors we carried the tropics around with us inside our clothes. Neither indoors nor out were we using any considerable part of the calorific value of our food in a biologic struggle against chill."
So although an Eskimo lives in a very cold climate, he has contrived to make his immediate environment, both outdoors and in, as warm as the tropics and in this heat the Eskimos and Dr. Stefansson, who lived with them, took a high-fat diet, composed almost exclusively of meat.
These facts about the Eskimo are not so surprising if we consider the position of fat in the diet of tropical and sub-tropical peoples.
The Bible is full of the praise of fat.
"And in this mountain shall the Lord of Hosts make unto all people a feast of fat things, a feast of wines in the lees, of fat things full of marrow."
The phrase, "to live on the fat of the land," which to-day epitomises all that is best in food, comes from the book of Genesis XLV, 17-18:
"And Pharaoh said unto Joseph . . . take your father and your house holds and come unto me; and I will give you the good of the land of Egypt, and ye shall eat the fat of the land."
Not only the ancient Hebrews, but hot-climate people in every part of the world, relish fat and regard it as the best kind of food for health. Its virtues are extolled in the religious folklore of Burma and Siam.
The Negroes of the American Deep South love fat pork. In central Africa the Negro gorges fat, when he can get it, — in preference to all other food.
Travellers in Spain and Italy know that the food is often swimming in oil and in Peru sticks of fat "crackling" are sold like candy-bars.
Australians in subtropical heat consume more meat per head than any other people of European descent except perhaps the Argentinian cowboys, who are the nearest to exclusive meat eaters in the world outside the Arctic.
Nevil Shute in his semi-documentary novel about the Australian outback, A Town Like Alice, described how an English girl tried, without much success, to wean the stockmen from their three steak meals a day to a "civilised" mixed diet.
It is clear from all this that fat is not a cold-climate food only but a much prized and essential food of people in hot countries.
To clinch the point, here is Henry Wallace Bates, friend of the great Charles Darwin, in his book, A Naturalist on the River Amazon:
"I had found out by this time that animal food was as much a necessary of life in this exhausting climate as it is in the North of Europe. An attempt which I made to live on vegetable food was quite a failure."
4. High-fat, high-protein diets are unbalanced and cause deficiency diseases.
Nothing is so dear to the heart of the dietician and the nutrition expert as the concept of a balanced diet.
In every civilised country dietetics is based on tables like "The Famous Five" and "The Basic Seven."
In these tables, foods are divided into categories according to the kind of basic nutriment they supply and the idea is that you must take something from each group every day to get a balanced diet and stay healthy. Yet it is obvious from what has been said already that men can and do remain fit indefinitely on a diet of meat alone.
Our ancestors, before they learnt to plant crops, had to subsist entirely on what meat they could kill. They survived and had children. So also do the primtive hunters of to-day. Eskimos who live without vegetable foods of any kind, on caribou meat, whale, seal meat and fish, do not get scurvy and are among the healthiest people in the world.
Eugene F. DuBois, M.D., Professor of Physiology, Cornell University Medical College, in his introduction to another of Dr. Stefansson's books, Not by Bread Alone, wrote in 1946:
"The text-books of nutrition are still narrow in their viewpoints. They do not seem to realise the great adaptability of the human organism and the wide extremes in diet that are compatible with health. The modern tendency is to encourage a wide selection of foods and this seems to be sensible and economical for the great bulk of our population. The propaganda is strong and on the whole excellent. Take for example the government pamphlet on the so-called 'Basic Seven.'
Eat some food from each group every day
(U.S. Government Chart)
|1||Green and yellow vegetables; some raw, some cooked, frozen or canned.|
|2||Oranges, tomatoes, grapefruit, or raw cabbage or salad greens.|
|3||Potatoes and other vegetables and fruits; raw, dried, cooked, frozen or canned.|
|4||Milk and milk products; fluid, evaporated, dried milk, or cheese.|
|5||Meat, poultry, fish or eggs or dried beans, peas, nuts or peanut butter.|
|6||Bread, flour and cereals, natural or whole grain or enriched or restored.|
|7||Butter and fortified margarine, with added Vitamins A and D.|
|In addition to the basic 7—eat any other foods You want|
"It is startling when we learn that large groups of active hunters in many parts of the world subsist on nothing but a small sub-division of Group 5. It is not quite as startling when we consider that the vegetarians live comfortably on all the groups except this very part of No. 5. The strictest vegetarians exclude also Group 4 and butter in Group 7."
Stefansson himself and a colleague, Dr. Karsten Ander son, finally demolished the balanced-diet-for-health idea in 1928 when they entered the Dietetic Ward of Bellevue Hospital, New York, to be human guinea pigs on an exclusively meat diet and remained, under the strictest medical supervision, on this diet for twelve months.
The committee in charge of the investigation must surely be one of the best qualified ever assembled to supervise a dietetic experiment. It consisted of leaders of all the important sciences related to the problem and represented seven institutions:
|American Meat Institute:||Dr. C. Robert Moulton;|
|American Museum of Natural History:||Dr. Clark Wissler;|
|Cornell University Medical College:||Dr. Walter L. Niles;|
|Harvard University:||Drs. Lawrence J. Henderson, Ernest A. Hooton, and Percy R. Howe;|
|John Hopkins University:||Drs. William C. McCallum and Raymond Pearl;|
|Russell Sage Institute of Pathology:||Drs. Eugene F. DuBois and Graham Luck;|
|University of Chicago:||Dr. Edwin 0. Jordan|
The Chairman of the committee was Dr. Pearl. The main research work of the experiment was directed by Dr. DuBois, who was then Medical Director of the Russell Sage Institute, and who has since been Chief Physician of New York Hospital, and Professor of Physiology in the Medical College of Cornell University. Among his col laborators were Dr. Walter S. McClellan, Dr. Henry B. Richardson, Mr. V. R. Rupp, Mr. C. G. Soderstrom, Dr. Henry J. Spencer, Dr. Edward Tolstoi, Dr. John C. Torrey, and Mr. Vincent Toscani. The clinical super vision was under the charge of Dr. Lieb.
The aim of the experiment was not, as the press claimed at the time, to prove or disprove anything. It was simply to find out exactly the effects on general health of an all-meat diet. Within that general plan, it was hoped that the results would answer several controversial questions:
|1.||Does scurvy arise when vegetable foods are withheld?|
|2.||Does an all-meat diet produce other deficiency diseases?|
|3.||Is the effect on the heart, blood vessels and kidneys bad?|
|4.||Will it encourage the growth of harmful bacteria in the gut?|
|5.||Will it cause a deficiency of essential minerals—notably calcium?|
Dr. MeClennan and Dr. DuBois published the results of this study in the American Journal of Biological Chemistry in 1930 under the title, "Prolonged meat diets with study of kidney functions and ketosis." Here are their findings summarised for convenience with those of other doctors who reported on other aspects of the experiment:
Stefansson, who was a few pounds over-weight at the beginning, lost his excess weight in the first few weeks on the all-meat diet. His basal expenditure of energy (metabolism or general rate of food using) rose from 60.96 calories to 66.38 calories per hour during the period of the weight loss, indicating an increase of 8.9%. He continued the diet a full year, with no apparent ill effects. His blood cholesterol level at the end of the year, while he was still on the diet, was 51 mg. lower than it had been at the start. (Remember this when reading about the next objection: the possibility of heart disease.) It rose a little after he resumed an ordinary, mixed diet. After losing his excess weight he maintained constant weight the rest of the year, though food was taken as desired. His total intake ranged from 2,000 to 3,100 calories a day. He derived, by choice, about 80% of his energy needs from fat and 20% from protein. These proportions are close to those derived by a person from his own tissues during prolonged fasting. The instinctive choice of about 80 % of the calories from fat seems to be based on selection by the metabolic processes of the body. It was found that with carbohydrate restricted in the diet, the appetite for fat greatly increased. The body adapted itself to a greater use of fat for energy when this substance was supplied in increased amounts.
So the answers to our five special questions listed above are all "no." Nothing untoward occurred and both subjects remained healthy, free from scurvy and other deficiency diseases, with normal heart and kidney functions. Their bowels behaved normally except that their stools became smaller and lost their smell. Deficiency of calcium or other minerals did not develop.
So much for the balanced diet. It is evidently not as important as some pundits would have us believe. In fact, many of the assumptions about diet on which national food policies are based may one day have to be revised.
5. High-fat diets cause heart disease
The medical term for a heart attack is coronary thrombosis. "Coronary" comes from the Latin word for a crown or circle. The small blood vessels which encircle the heart, supplying the heart muscle, are called coronary arteries. A coronary thrombosis is a clot or thrombus in one of these arteries.
In 1921 coronary thrombosis was a rarity and accounted for only 746 male deaths in Britain. In 1956 the figure was 45,000. It is still going up.
Even allowing for the survival of more people into the coronary-prone age group, and for better diagnosis, the rise is alarming.
One theory put forward to account for this epidemic of heart attacks, blames the fat we eat. According to this theory, too much dietary fat is supposed to raise the level of a waxlike chemical called cholesterol in the blood, and form deposits on the linings of arteries, narrowing their bore and encouraging the blood to clot within them.
The deposits are called atheroma from two Greek words ather = porridge and oma = tumour, and the process is known as atherosclerosis.
The fat-furs-the-arteries theory really began with animal experiments in the nineteen-thirties which showed that feeding large quantities of fat to rats raised their blood cholesterol and induced atherosclerosis rapidly.
This work has never been repeated in man since it would be impossible to do so under experimental conditions. But it suggested a link between fat in the diet, blood cholesterol and atherosclerosis, and inspired a number of statistical studies, notably those of the American biochemist, Dr. Ancel Keys, which showed that coronary deaths were rare among primitive people who ate little fat.
Mortality figures for European countries published after the war seemed to confirm this.
They revealed a sharp fall in the number of deaths from diseases of the heart and arteries between 1939/45, followed by a rise when rationing ended.
On the basis of the earlier work with animals, this rise was attributed to a raised blood cholesterol from an increased consumption of bacon, butter and other animal fats.
There was certainly no direct evidence that eating fat caused coronary thrombosis in man. But it was argued that if a high-fat diet raised the blood cholesterol of rats and mice and increased their liability to atheroma, the same thing might happen in humans heavily indulging in fats after the lean years of rationing.
The weak link in this argument is that we do not know how coronary thrombosis comes about in man. It can occur without atherosclerosis and with a normal blood cholesterol.
So that although it is certainly possible to reduce the blood cholesterol by eating little or no fat, there seems little point in doing so since cholesterol is an essential constituent of most tissues and can be synthesised in the body easily from carbohydrate.
Nor is there any evidence to show that a low blood cholesterol will either delay the onset of atherosclerosis or prevent a coronary thrombosis from happening.
A number of other findings have since cast doubt on the idea that a high total fat consumption is an important cause of coronary thrombosis.
Australians, who had fewer coronaries during the war, ate no less fat. And in Great Britain, while the mortality from heart attacks has risen steeply since the war, consumption of fat has gone up only 7 per cent.
A more interesting theory is now current. It is that the kind of fat you eat is more harmful than the amount. The proportion of "hard" to "soft" fat in the diet is said to be critical.
This theory has led to claims that "unsaturated" cooking fats and oils protect against coronary thrombosis.
The soft, unsaturated fats stay liquid when cool and include the natural vegetable oils like olive oil, cotton seed and sunflower seed oil as well as the marine and fish oils. Saturated fats set hard when cool and include animal fats, hydrogenated vegetable fats and shortenings, margarine and solid cooking fats.
In 1955, Dr. Bronté Stewart, then at Oxford, found that the blood cholesterol level could be lowered by giving people more unsaturated fat. But a survey of countries with different tastes in fats and oils fails to show that this protects against heart disease, or that eating mainly saturated fats encourages it. Norwegians, who eat a lot of saturated fat as margarine, have fewer fatal coronary thromboses than New Zealanders who eat little.
And if the Norwegians are protected by the unsaturated oils in the fish they eat, then it is strange that Aberdeen, where a lot of fish is eaten too, has twice the coronary death rate of Oslo.
Indeed Dr. Bronté Stewart has recently drawn attention to the weakness of the links between coronary thrombosis and either the kind or the amount of fat we eat.
Writing in the British Medical Bulletin, in September 1958, he said that while there is strong evidence for a direct connection between diet and the level of cholesterol in the blood, any links between these two and atherosclerosis and coronary thrombosis are not convincing.
"Any policies regarding preventive programmes that the alarming increase in incidence demands," he wrote,"would be founded more on assumptions than on facts."
The United States Department of Health is in agreement with this and early in 1960 issued the following statement:
"It is the opinion of the Food and Drug Administration that any claim, direct or implied, in the labelling of fats or oils or other fatty substances offered to the general public that they will prevent, mitigate or cure diseases of the heart or arteries is false and misleading, and constitutes misbranding within the meaning of the Federal Food, Drug and Cosmetic Act."
It is difficult to see how the anti-fat theory has gained so much ground. History does not support it. The men who won the battle of Agincourt, the men who broke the Spanish Armada and the heroes of Waterloo all fed on butter, fat beef and fat bacon. They did not suffer from coronary thrombosis. If they had done so, the careful medical observers of the time would have described it.
It is only since the introduction of highly refined and processed cereals and sugars into the diet that civilised man has been plagued with coronaries.
If the fat we eat is implicated at all, it is likely that artificially processed fats are to blame rather than the natural animal and vegetable fats which have been our best food from the beginning of history.
Dr. H. M. Sinclair's name is associated with this view. In a letter published in The Director (February 1960), he claimed that naturally-occurring fatty acids (removed from present-day edible fats by modern methods of production and processing), could protect against coronary thrombosis.
He called these substances "essential fatty acids" (E.F.A.) because the body needs them for its economy and must rely on a ready-made supply in the diet since it cannot make them for itself.
It is wrong, he said, to condemn animal fats and praise vegetable fats. Each fat should be considered good or bad according to the amount of E.F.A. in it.
On this basis, coconut oil is bad, because it is almost devoid of E.F.A., while some margarines are quite good, being manufactured to contain useful quantities, and lard varies with the way the pig is fed.
For completeness, one other theory must be mentioned. That high-fat meals accelerate the clotting of blood and so increase the likelihood of a thrombosis.
This is based on observations made at the laboratory bench, with blood in test tubes, not in living people. There is no evidence linking fatty meals with the time of coronary disasters in patients.
From this confusing but fascinating field of study two conclusions may fairly be drawn about advising a high-fat diet for obesity.
1. When a person is over-weight and has already got heart disease
There is at present no good evidence of the effect of reduction of dietary fat on the progress of established coronary artery disease.
But when it can be shown that the blood cholesterol of such patients is raised, there is a case for putting them on a dietary regime designed to bring the blood cholesterol down. This need not mean the restriction of total fat, although such a diet (which is very unpalatable) will often have the desired effect.
Natural, unprocessed vegetable oils and fish oils will also reduce the blood cholesterol and certain substances, like sitosterol, which block the absorption of cholesterol, can also be given for this purpose.
But the most valuable single measure in prolonging the life expectancy of an obese patient with coronary artery disease is weight reduction and if this can be achieved on a high-fat, high-protein diet the benefits will far out-weigh any possible danger from a raised blood cholesterol. The sensible thing for such a patient would therefore seem to be weight reduction by dietary means with a good intake of unsaturated fats — corn oil, soya bean oil, peanuts, kippers and herrings to depress the blood cholesterol.
2. When an over-weight person has not got heart disease
The beneficial effect of weight reduction in preventing the onset of coronary thrombosis is generally accepted, based on life insurance experience over many years. And there is no scientific support for the suggestion that eating a lot of fat leads to "furring of the arteries" and increases the chance of having a coronary thrombosis.
One of the acknowledged experts in the field of epidemiology and medical statistics has refuted the suggestion that the intake of dietary fat has anything to do with the rise in the number of deaths from coronary thrombosis.
Speaking to the Manchester Medical Society on 23rd January, 1957, Dr. J. N. Morris, Director of the Medical Research Council's Social Medicine Research Unit in London, was reported in the Lancet as saying:
"What might be called the 'appeal to epidemiology' was persistently refusing to confirm the hypothesis of a single or simple dietary aetiology for ischaemic heart disease. In the present climate of opinion such a negative role was exceedingly uncomfortable! But it was not possible, in time series or other series, to correlate what was known of the mortality from coronary heart disease with what was known of trends in fat consumption. Thus, the great variations of mortality among Western countries having similar high-fat intake disposed of any story that total fat consumption was the critical factor.
Changes in animal-fat consumption in the United King dom during the present century could be related to the changes in coronary atheroma found in the London Hospital records, but they showed no relation to the Registrar-General's figure of mortality from coronary heart disease. The trend of consumption of butter-fat in the United Kingdom showed absolutely no relation; the steep increase in coronary deaths since 1943 was only one illustration of this. Changes in vegetable-fat intake followed the mortality experience more closely; and changes in the hydrogenated-fat intake were even more closely reflected in the mortality figures, except for the social-class distribution of coronary mortality, which did not agree with the pattern of margarine intake."
On 10th April, 1957, Dr. John Yudkin, Professor of Nutrition at London University, in his farewell address as Chairman of the Nutrition Group of the Society of Chemical Industry, related ·diet to deaths from coronary thrombosis in three ways:
|1.||By comparing diet with deaths in different countries.|
|2.||By comparing the deaths in different social classes.|
|3.||By comparing trends in diet with trends in mortality in Britain over the last thirty years.|
None of these comparisons showed any significant correlations except a slight association between coronary thrombosis and high living standards. From numbers of graphs based on the most painstaking statistical research, the answers to the questions about dietary fat and deaths from coronary artery disease emerged as follows:
|1.||As fat intake rises do deaths from coronary thrombosis rise?||No.|
|2.||Is there a relationship between the proportion of calories obtained from fat and the incidence of coronary thrombosis?||No.|
|3.||Is the intake of animal fat related to coronary thrombosis?||No.|
|4.||Is there a relationship with butter, cheese and milk fat consumption?||No simple relationship|
|5.||With vegetable fats?||No.|
|6.||Hydrogenated or saturated fats: margarine, shortening, etc.?||No.|
After pointing out that even if you show a statistical relationship between two things you do not show that one causes the other, Professor Yudkin concluded that not one single dietary factor shows any clear statistical relationship with coronary thrombosis. Later he published his survey in the Lancet on July 27th, 1957, and again concluded that on the available evidence it was
"difficult to support any theory which supposes a single or major dietary cause of coronary thrombosis."
On that point most authorities now seem to be in agreement and in the present state of our knowledge there is absolutely no justification for scaring an obese person in normal health off a high-fat diet for the treatment of his obesity. On the contrary, there is evidence to show that the loss of weight which he can easily achieve on a high-fat, high-protein, low-carbohydrate diet will lessen considerably his chances of having a heart attack and will also add years to his expected span of life.
Summing up the position, the British Medical Journal, in its leading article on 13th July, 1957, said:
"Until we have more precise information on the relationship, if any, between dietary factors and coronary disease, there is no need for the middle-aged man to forgo his breakfast of egg and bacon in favour of cereal and skim milk, followed by toast and marmalade with a scraping of butter."
In spite of a world-wide research effort, "more precise information" has not appeared at the time of revising this for the Fontana edition (Sept. 1960) and it is appropriate to close with a story about the Jack Spratts of medicine told recently by Dr. Charles H. Best, co-discoverer of insulin.
He had been invited to a conference of heart specialists in North America. On the eve of the meeting, out of respect for the fat-clogs-the-arteries theory, the delegates sat down to a special banquet served without fats. It was unpalatable but they all ate it as a duty.
Next morning Best looked round the breakfast room and saw these same specialists—all in the 40-60 year old, coronary age group — happily tucking into eggs, bacon, buttered toast and coffee with cream.
If the very people who started the anti-fat scare do not apply it seriously to themselves why should ordinary men and women be expected to avoid the food which has been, with protein, the staple diet of mankind for nine-tenths of our time on earth?
The evidence against fat is full of inconsistencies. A better case can be made out for lack of exercise. We certainly ate more butter when the war was over, but we also bought more motor-cars and started to put in long hours sitting in front of the television.
Eskimos on their native diet eat more fat than anyone else, but they lead more strenuous lives.
More bus drivers die of coronaries than conductors, who are up and down stairs all day. Treasury clerks have more coronaries than postmen.
Americans, who get more heart attacks than anyone else, have more cars and elevators.
The most impressive evidence of all was obtained by Morris and Crawford (British Medical Journal, 1958) by asking pathologists all over the country to report on their next 25 post-mortems in the 40-70 age group, no matter what the cause of death.
Healed coronary thrombosis was found in more men in light work than in heavy occupations. More of the light workers had high blood pressure and these were the ones with the greatest number of coronary thrombosis scars.
This brings us back to obesity, which is closely correlated with high blood pressure.
Get your weight down by keeping active and avoiding carbohydrate and you will keep your blood pressure normal, and have the best chance of avoiding a coronary.