Fasting: Eat Less And Keep Your Marbles
For five days a week you don’t feel as though you’re dieting because you can eat normally
March 13, 2017 | By:
There is increasing evidence that regular fasting has a positive effect on the brain and keeps you sharp. The good news is that it needn’t mean nil-by-mouth

Fasting_5-2 diet-pea-on-plate-620 Bigstock“I fast for greater physical and mental efficiency.” So said Plato, and recent research by researchers at the National Institute of Ageing in Baltimore suggests that the great philosopher may have been on to something. If you’re interested in keeping Alzheimer’s and Parkinson’s at bay, and keeping your mental faculties sharp as you age, cutting down on your food twice a week could help.

Professor Mark Mattson, head of the Institute of Ageing’s neuroscience laboratory and professor of neuroscience at the John Hopkins University School of Medicine in Baltimore, says that regular fasting “can protect the neurons against the adversities of ageing and may protect against Alzheimer’s and Parkinson’s”.


The beneficial effect on health of fasting has been recognized for a while. Animals put on low-calorie diets have been shown to live up to 50 per cent longer than animals that aren’t.

However, there is now also a considerable body of evidence supporting the positive effects of fasting on the brain, and this makes interesting reading for those of us keen to keep our mental capabilities up to scratch as we enter the second act of our lives.

As Professor Mattson points out, the evidence of the last couple of decades has made it clear that over-eating and sedentary lifestyles are risk factors for brain disorders as we age. The research he and his team have carried out has shown that “intermittent fasting has quite strong beneficial effects on the brain in animal models of Alzheimer’s and Parkinson’s”.

They are about to run studies to confirm the effects in humans in conjunction with the University of Manchester.

How does fasting affect the brain?

Quite why there is this effect has not yet been fully understood but, according to Professor Mattson and his team, fasting seems to induce a mild beneficial stress response in cells throughout the human body, which makes the cells stronger and more resistant to disease.

It is thought that cutting back on food raises the production of nerve cell growth factors within the brain and these, as the name suggests, both cause the nerve cells to grow more and to protect the neurons from the effect of degenerative brain diseases.

However, fasting needn’t be quite as terrifying or restrictive as it sounds. Cutting back food to around 500 calories per day for two consecutive days and then eating normally the rest of the week is sufficient to create the positive effect, and there is often a side benefit of weight loss.

In a talk to the American Association for the Advancement of Science in Vancouver, Professor Mattson said: “Reducing your calorie intake could help your brain, but doing so by cutting your intake of food is not likely to be the best method of triggering this protection.

“It is likely to be better to go on intermittent bouts of fasting, in which you eat hardly anything at all, and then have periods when you eat as much as you want. In other words, timing appears to be a crucial element to this process.”

This means that for five days a week you don’t feel as though you’re dieting because you can eat normally. And crucially, because of this you’re more likely to stick to the regime. It is, after all, psychologically easier to stick to a routine of ‘two days on, five days off’ than to permanently cut back on the amount you eat. This brain-sharpening regime can then be fitted around social commitments.

Diet vs destiny

More and more research is drawing the same conclusion: that how we age is as much to do with the decisions we make about the food we eat and the lifestyles we lead as it is about the destiny laid out in our genes. As Patrick Holford and Jerome Burne point out in their fascinating book The 10 Secrets of Healthy Ageing, it is “increasingly clear that we can all make changes to the genetic hand we were dealt”.

Dementia now affects around 820,000 people in the UK, with over one in three of us having a close friend or family member suffering from it. It is an affliction of an ageing population and something all of us have to think about as we grow older.

Perhaps – if feeling slightly hungry a couple of times a week helps keeps the brain sharp – then skipping breakfast and lunch, and swapping that bowl of pasta and glass of red wine for soup and salad tomorrow, isn’t such a great sacrifice.