by Zoë Harcombe
Author of Why do you overeat? When all you want is to be slim,
Stop Counting Calories & Start Losing Weight,
and The Obesity Epidemic: What caused it? How can we stop it?
In a study of formerly obese people, researchers at the University of Florida found that virtually all said that they would rather be blind, deaf or have a leg amputated than be obese again.(1) That is the extent of our desire to be slim and yet two thirds of people in the United Kingdom, USA and Australia are overweight and one quarter obese. Why? Why on earth do we have an obesity problem, let alone an epidemic, when we so desperately want to be slim?
I set out to answer that question in the late 1980's and my book, The Obesity Epidemic: What caused it? How can we stop it? was the culmination of that quest. At the time of starting my research, the most recent World Health Organisation statistics for UK obesity levels were for 1972 and they showed that 'only' 2.7% of men and the same percentage of women were obese.(2) By 1999, these figures were eight times higher for men and almost ten times higher for women (22.6% and 25.8% respectively).
The smoking gun
The obvious question to ask is - what happened? What caused obesity rates to increase almost tenfold in fewer than three decades? Did something change in the late 1970's/early 1980's, which is when graphs for obesity rates show a trajectory like an aeroplane taking off? Yes, it did. We changed our diet advice.
A better description would be - we did a U-Turn in our dietary advice. As far back as 1869, Tanner's 'bible' The Practice of Medicine set out what we knew about food and weight: "Farinaceous and vegetable foods are fattening, and saccharine matters are especially so."(3) Floury and vegetable (interesting) foods are fattening and sugary stuff especially so.
In 1977 the US changed its diet advice. In 1983 the UK followed suit - obesity rates rose first in the USA and the UK has always followed not far behind. We changed from knowing that starch is fattening to saying "base your meals on starchy foods."
Analysis of the 2008 UK Family Food Survey reveals that we eat 1,536 calories of processed food daily. Both the UK and USA average citizen is consuming over 1,100 calories of flour and sugar daily - that farinaceous and saccharine stuff.
The change in diet, in so called developed countries, has been dramatic and catastrophic. So, why did we do it?
In 2009, I wrote to the UK Food Standards Agency (the American equivalent would be the Food & Drug Administration, FDA) and asked why they told us to base our meals on starchy foods.
This is the verbatim reply that I received:
"Diets high in fat are associated with increased risk of cardiovascular disease (CVD), therefore it was recommended that people reduce their fat intake. It was advised that starchy carbohydrates should replace the reduction in fat as an energy source."
So, we didn't tell people to base their meals on starchy foods because we knew these to be good. With no claim of causation, a mere hint of association, we decided that fat was bad and therefore people had to eat something else - carbohydrates.
The diet heart hypothesis
Ask a number of cholesterol sceptics about the origin of the heart/diet hypothesis and The Seven Countries study will feature somewhere in the explanation.
Those who go back further may tell you about ‘Bugs Bunny'. In 1913, a Russian pathologist called Nikolai Anitschkow decided to feed purified cholesterol to rabbits and he managed to get their blood cholesterol levels in excess of 1,000 mg/dl(4) (five times anything considered ‘normal' today). He then noticed the formation of "vascular lesions closely resembling those of human atherosclerosis" forming in the arteries of the rabbits.
The obvious flaw in the experiment should have been that rabbits are strict herbivores. They do not eat animal products, which is the only source of cholesterol. Hence rabbits are in no way designed to digest cholesterol or animal fat and no one should be surprised if cholesterol, or animal fat, ended up stuck in any part of the poor rabbit. The only surprise is that no one thought to ask Anitschkow why he was feeding cholesterol and animal fat to herbivores.
Interestingly, a) the rabbits didn't go on to develop heart disease and b) a parallel test was done on rats and dogs (omnivores) and feeding cholesterol to these species failed to produce lesions.
This does seem to be the origin of the notion that cholesterol and atherosclerosis could be associated. Ancel Keys, an American doctor, had done a pioneering experiment on calorie deficits in humans (The Minnesota Starvation Experiment). The results of this, 1,385 pages in total, were published in The Biology of Human Starvation (1950)(5). This study made Ancel Keys the man of the moment and he no doubt wanted to follow it with something equally impactful.
Keys spent the early years of the 1950's trying to establish a link between cholesterol in food and cholesterol in the blood because he held a belief (literally pre-judged) that cholesterol in the blood causes heart disease. Keys did multiples of studies, changing the diets of his human ‘guinea pigs', and he presented his conclusions in The Journal of Nutrition, November 1955:
"It is concluded that in adult men the serum cholesterol level is essentially independent of the cholesterol intake over the whole range of natural human diets. It is probable that infants, children and women are similar." I.e. I only tested adult men and there is no relationship between cholesterol eaten and cholesterol in the blood and it is probable that there will similarly be no relationship for women or children.
In 1997 Keys put this even more assertively: "There's no connection whatsoever between cholesterol in food and cholesterol in blood. And we've known that all along. Cholesterol in the diet doesn't matter at all unless you happen to be a chicken or a rabbit."
If only Keys had accepted his own evidence in the early 1950's, but he wanted to find an explanation for heart disease and he was not about to be deterred. For some reason, which I find inexplicable, he then turned to fat (the entire literature on this topic is very vague about "fat" vs. "saturated fat" and Keys' early writings are also very vague on the topic).
Here is the logical pathway to illustrate the illogicality of trying to build a case against fat:
i) Only animal foods contain cholesterol (meat, fish, eggs, dairy). NO non animal foods contain cholesterol.
ii) All animal foods contain fat - saturated and unsaturated (monounsaturated and polyunsaturated). Some animal foods may be very low in fat (e.g. white fish), but they all contain fat.
iii) If there is no link whatsoever between increased consumption of foods containing cholesterol and blood cholesterol levels, there can be no link whatsoever between increased consumption of animal foods and blood cholesterol levels, since only animal foods can be increased in consumption to increase consumption of cholesterol.
Keys' first claim of an association between fat and heart disease was presented at the Mount Sinai hospital in 1953. The graph he showed appeared to illustrate an association between fat consumption and heart disease for the USA, Canada, Australia, UK, Italy and Japan.
Having pre-judged that fat, cholesterol and heart disease were aligned; Keys started the Seven Countries Study in 1956. The results were published in Circulation in 1970(6) . I have read all twenty volumes of the study and I take it apart, piece by piece, in Chapter Eight of The Obesity Epidemic: What caused it? How can we stop it?
Interestingly - Keys claimed a lot less than people who may not have read the study in full claim that he did. His three claims, in the 1970 report, were:
1) Coronary heart disease (CHD) tends to be directly related to serum cholesterol;
2) Serum cholesterol tends to be directly related to saturated fat as a proportion of the diet;
3) CHD is as closely related to saturated fat as it is cholesterol.
(1) Colleen S.W. Rand and Alex M. C. Macgregor, "Successful weight loss following obesity surgery and the perceived liability of morbid obesity", International Journal of Obesity, (1991). (The study results are presented in the summary of this book).
(2) https://apps.who.int/infobase/Indicators.aspx. Wadsworth M, Kuh D, Richards M, Hardy R, The 1946 National birth cohort (MRC national Survey of Health and development).
(3) Thomas Hawkes Tanner, The Practice of Medicine, (p217), (1869).
(5) Ancel Keys, The Biology of Human Starvation, Minnesota University Press, (1950).
(6) Keys et al. Circulation, (April 1970).