I want to let you in on one of the best kept secrets in modern medical science.
Did you know that by simply delaying breakfast for several hours, on a regular basis, you could :
. lose weight
. lower your blood pressure
. reduce your cholesterol levels
. decrease your risk of developing Type 2 diabetes
. lessen your chances of getting cancer
. enjoy better cognition and possibly avoid dementia
. rejuvenate your skin
. and perhaps, even live longer?
“Rubbish!”, you say … but there is an accumulating body of experimental work in animals and clinical trial evidence in humans showing that regular intermittent fasting, or IF – eating only during a 6-8 hour period each day, for example – will enable you to achieve these health outcomes (provided, of course, that you don’t sneak any snacks between times).
The science behind IF is fascinating. It is all discussed in depth in an article in the New England Journal of Medicine of December 2019. (Here it is for those interested in the long read – Effects of Intermittent Fasting on Health, Ageing and Disease. de Cabo and Mattson; New England Journal of Medicine 2019; 381: 2541-2551.) There is a maxim in the world of science that “nothing in biology makes sense, except in the light of evolution” This means, that for us to try to understand the phenomenon of IF and its benefits, we have to look back on how humans have evolved over the past 2 million years. For all but the last 10,000 years or so, humans have lived as hunter/gatherers, enduring regular periods of starvation between successful hunting forays. Our metabolism has evolved to adapt to these circumstances.
From the science we know that when we eat, food is broken down by enzymes in the gut into molecules that are absorbed in our bloodstream. Carbohydrates are broken down into sugar which our cells metabolise as the default fuel to generate energy. Any sugar that isn’t used is stored as fat, principally in our subcutaneous tissues.
But when we are deprived of food for more than 10 hours, a remarkable adaptive survival mechanism kicks in. Our metabolism switches to another fuel which is derived from our own fat reserves. Fat is broken down into its constituent fatty acids which are transported in the blood stream to the liver, where they are converted into energy-rich molecules, known as “ketone bodies”.
These ketone bodies not only serve as a potent new energy source, taking the place of sugar to fuel muscle and brain function, but also have an important role as “signalling molecules”, turning on a number of highly orchestrated cell and organ functions that are vital to our mental and physical performance, as well as bolstering our resistance to disease.
Principal among these cellular functions is a process called “Autophagy”— an ugly word for a beautiful process which was revealed by Ohsumi, who won the Nobel prize for this work in 2016. Autophagy is a process whereby decrepit cells are revitalised and rejuvenated by removing their worn out parts and junky proteins and recycling them to build new and fresh cellular components. At a tissue or organ level autophagy translates into healthier-looking skin, better cognitive function, improved kidney function and better control of blood sugar and lipid levels. It may even undo, or at least halt, life-threatening hardening of the arteries.
Over and above their key function in turning on the process of cellular rejuvenation, ketone bodies also have an important role in maintaining a healthy brain by stimulating the expression of the gene which causes the formation of brain-derived neurotrophin, a protein which favours the survival of existing brain cells and promotes the growth and development of new ones. This has obvious implications for brain health and for psychiatric and neurodegenerative diseases.
And then, there is their effect on ageing. It has long been known that experimental mice, subjected to IF, live longer than their matched controls, which are allowed to eat normally.
David Sinclair, an Australian scientist who is professor of genetics at Harvard Medical School and who has forged a global reputation for his research into ageing, has recently written a book titled “Lifespan : Why We Age and Why We Don’t Have To” (Harper Collins 2019.)
In his book Sinclair details numerous studies showing how longevity correlates very closely with various forms of intermittent fasting practiced by different populations around the world. He postulates that fasting turns on longevity genes in our epigenome (which works to support the integrity and function of our genetic code),ensuring a longer and healthier life. He writes: “After twenty-five years of researching ageing and having read thousands of scientific papers, if there is one piece of advice I can offer, one surefire way to stay healthy longer, one thing you can do to maximise your lifespan right now, its this: eat less often”.
(And if you’re wanting even more to read then try The Obesity Code by Jason Fung MD (Scribe Publications 2016).
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So it is evident that IF is evolutionarily embedded within our physiology and that its benefits are legion.
Promoting an IF practice would probably be the single, most cost- effective public health initiative we could undertake as a nation for preventive health maintenance.
The only caveat to this advice would apply to diabetics and pregnant women, who should first discuss any significant change in their dietary habits with their doctor.
I know it’s hard to break ingrained habits, and we have all been fed the line that “breakfast is the most important meal of the day” by the likes of Dr Kellogg and Uncle Toby. But the science has persuaded me that it is better to skip breakfast or defer it until lunchtime.
My wife and I have been practicing the 6-8 hr eating:18-20 hr intermittent fasting form of IF ever since becoming aware of the New England Journal article in early 2020. We thought hunger pangs would be a problem but we were pleasantly surprised to find that fasting actually tends to suppress the appetite.
We have both lost a couple of kilograms and my fasting blood sugar has gone from borderline elevated, to normal. It is still early days, so we can’t attest to any other tangible benefits. However, we intend to follow the science and stick with it, in the belief that these benefits will emerge in time.
* This article was written by Anthony J Edis MB, BS, (Hons), MD, FACS, FRACS.