If you haven’t read Part 1 of this blog post, please click here – this second part will make much more sense if you do!
This is Professor Tim Noakes’ opinion on diabetes and eating protein and carbohydrate – continued from yesterday’s post. If you have any questions for Prof. Noakes, please post them here and we’ll ask him for you when we interview him for the next issue of Sweet Life.
So I discovered that the foundation of the “prudent diet” begins in the head of one man – an American biochemist, Dr Ancel Keys, in the early 1950s. Ten years earlier he had convinced the US Military to adopt his unproven food combination – the K(eys) rations – to replace what for centuries had become established as the ideal food for troops on the move – pemmican, a mixture of protein and fat made from the bison – the staple food of the American Plains Indians before the intrusion of the white man, who shot out their bison and forced them onto “reservations”. The evidence is that when eating bison, the Plains Indians were the tallest and healthiest of all human populations. Today they are amongst the least healthy with rates of obesity and diabetes second only to those found in the Pacific Islanders.
Infatuated by this success, Keys next set out on an even more daring escapade – the quest to change the eating behaviours of the entire Western world. He would convert the world to his belief that a high fat diet was the singular cause of ill health, especially heart disease, in all humans. This ran contrary to more than 100 years of an alternative wisdom that it is the carbohydrate content of the diet that causes both obesity and diabetes – two established precursors of heart disease.
Within a short time Ancel Keys achieved his goal of demonizing fat as the exclusive dietary cause of heart disease and as a consequence of all human ill-health. By 1977 the first US Dietary Guidelines were published – these emphasized the need to restrict the intake of “artery-clogging” fats and in their stead to eat “heart healthy” carbohydrates.
Thus began the single greatest nutritional trial in human history – within a few years, the foodstuffs highest in the two key constituents that humans had become adapted to through 1-2 million years of our evolution – fat and protein – were replaced with those – novel sources of carbohydrate especially grains and cereals – to which we humans have been exposed for less than 1% of our entire existence.
Now three decades into this trial, it is perhaps time to take stock of what has been the outcome of this remarkable trial. The answer is what we might call the “elephant in the room” that everyone wishes to ignore. It is the rampant increase in the prevalence of obesity and adult-onset diabetes, most especially in North America and some European countries, to the point where in 20 years time the cost of treating adult-onset diabetes will bankrupt the medical services of the United States and Great Britain. Importantly this increase in the prevalence of diabetes and obesity has occurred as Americans have adopted the key elements of the “prudent diet” – the intake of carbohydrates in North America has increased progressively over the past 3 decades whereas the consumption of especially saturated fat and meat has fallen to the lowest levels in one hundred years.
Next I reviewed both the scientific and popular literature which shows, at least to me, that the only one way to reduce my risk for developing adult-onset diabetes is to minimize my daily carbohydrate intake of carbohydrates. A wealth of scientific studies have shown that, by reducing the amount of glucose produced by the liver in diabetics and by increasing disposal of glucose into body storage sites, a carbohydrate-restricted diet dramatically improves glucose control. As a result, the need for insulin falls dramatically. Thus I learned that a carbohydrate-restricted diet would reduce the stress on my pancreas and my arteries (as a result of better glucose control) thereby hopefully allowing me to avoid the development of full-blown diabetes for some time yet.
As predicted by these findings, my adoption of a high fat/moderate protein/ very low carbohydrate diet has produced encouraging improvements in all my blood markers of pre-diabetes and in all those blood cholesterol parameters considered, incorrectly I believe, to predict risk of heart attack. So in contrast to the conventional wisdom but in keeping with all the published literature, my blood cholesterol parameters are now much “healthier” on a high fat diet than they were a year ago when I was following the supposedly “heart healthy” high carbohydrate diet.
More importantly my weight has fallen by 15kg; I have dropped my running time in 21km races by more than 40 minutes so that I am now aiming to break 50 minutes for 10km (at age 62); I again have the energy that I remember in my twenties, and I am no longer hungry. Instead I now eat only when the thought strikes me that it would be a good idea to have something to eat. I interpret this as evidence that I have returned to a primal state when we ate in order to live and not the reverse. This absence of hunger has taught me that carbohydrates, especially refined carbohydrates, are addictive in that, in those like myself, they stimulate over-eating, progressive weight gain, increasing lethargy and ultimately the onset of adult-onset diabetes.
I appreciate that many of my colleagues who manage diabetes do not agree that a low carbohydrate diet should be prescribed for those with either Type I or Type II diabetes.
All I can report is that, as a pre-diabetic, I have tried both a high carbohydrate and a low carbohydrate diet. The one clearly exacerbated my condition; the other has been associated with a dramatic improvement in my quality of life and in all my biomarkers of metabolic and cardiovascular health.
The decision of what I should eat is therefore, at least for me, very simple.
Written by Professor Timothy Noakes OMS, MBChB, MD, DSc, PhD (hc), FACSM, FFSEM (UK).
Discovery Health Professor of Exercise and Sports Science at the University of Cape Town and the Sports Science Institute of South Africa.