Intermittent Fasting  

When it comes to diet, there are a lot of voices out there telling us what to eat, but since books like “The 5:2 Diet” burst onto the scene a few short years ago, there are now voices telling us how to eat. Mark Mattson, a Professor of Neuroscience at The Johns Hopkins University and current Chief of the Laboratory of Neuroscience at the National Institute of Aging, hopes that this latest diet trend is more than a fad. It’s called Intermittent Fasting and he claims it can make us healthier and more productive. 

With extended life spans, comes a problem. More of us are advancing into what Mattson calls “the danger zone for Alzheimer’s Disease and Parkinson’s Disease [1].” Mattson cited a prediction that the number of people with Alzheimer’s Disease could triple by 2050 – a truly concerning health prophesy. 

Mattson and his team have published an impressive body of work on the issue of fasting. They discuss how “fasting twice a week could significantly lower the risk of developing both Parkinson’s and Alzheimer’s Disease [2].”

The idea of fasting is not new. It’s been a part of religious rites for as long as history remembers. Philosophers such as Plato used fasting to clear the mind, and the science behind it shows that there could be good reason as to why that works. Since Roman times, fasting has been a part of epilepsy management. We call it ketones nowadays as our scientific and biochemical advancements explain that the release of ketones during fasting helps manage seizures. The Roman’s called it demon possession and thought that fasting drove them away [1].

Well. Right method. Absolutely the wrong conclusion as to why it worked. 

Here’s an interesting finding of some of Mattson’s work. “Calorie restriction extends life span and retards age-related chronic diseases in a variety of species including rats, mice, fish, flies, worms and yeast [2].”

“Its been known for a long time that a way to extend the lifespan of laboratory animals is simply to reduce their energy intake. In rats and mice one can increase their lifespan by 30 or 40%.” Mattson and his team started looking at the effects of energy restriction on the brain in the context of age-related neurodegenerative disorders and found that they could slow down degeneration in certain areas by reducing energy intake.

“Fasting does good things for the brain,” says Mattson. Animal studies show us why but bit-by-bit this is advancing into the human experience.

“In this country as you know, being overweight is a big problem. It’s not only a risk factor for cardiovascular disease and diabetes, certain cancers, but emerging evidence suggests that it’s also a risk factor for age-related cognitive impairment and possibly Alzheimer’s Disease.”

So far the evidence is showing that intermittent fasting is good for the body – reducing inflammation and oxidative stress, and that energy metabolism shifts to start burning fats and producing ketone bodies.

Intermittent fasting can take on a number of forms. The 5:2 diet, whereby you eat normally for 5 days a week and restrict your caloric intake to 500 calories on two separate days, is just one method. Another method restricts the time in a day where you eat to 8 hours. You fast for the other sixteen – but for a large chunk of that, you are sleeping.

Why does fasting boost brain power? 

“Fasting is a challenge to your brain. Your brain responds to that challenge (of not having food) by activating adaptive stress response pathways that help your brain cope with stress and resist disease.”

It makes sense, even in an evolutionary context. “If you’re hungry and haven’t found food, you better figure out how to find food. You don’t want your brain to shut down if you’re hungry.” That’s what they find in animals – those neuronal circuits are more active.

“Some of the changes that occur in intermittent fasting also occur in vigorous exercise.” In fact, fasting stimulates the production of “neurotrophic factors such as BDNF and FGF*.” These promote the growth of axons, dendrites, and the formation and strengthening of synapses and the process of neurogenesis [1].

Some key findings laid out by Mattson include:

  • Ketones suppress seizures. They also provide an alternative fuel and boost the energy levels within the neurons.
  • Fasting can increase the number of mitochondria in your nerve cells. Neurons respond adaptively to this, just like your muscles respond adaptively to using your muscles.
  • Fasting will improve the ability of your nerve cells to repair DNA.

In an article appearing in Johns Hopkins magazine, a poignant question was asked: “Wouldn’t reducing calorie intake overall also help the brain?” 

The answer: “Apparently not, or at least not as much. Sticking to an intermittent crash diet, with no more than 500 calories two days per week, primes the brain for protection, he [Mattson] says. Studies show that keeping calories at around that level stimulates two messaging chemicals that operate at the cellular level and are key to the growth of brain cells in animals and humans… The shock of fasting leads the brain to create new cells. As neurons are coaxed to grow, the brain becomes more resistant to the effects of protein plaques that underlie cases of Alzheimer’s, or the damage inflicted by Parkinson’s [3].”

So apparently it is the fast and not simply the caloric restriction that leads to all the good stuff. We don’t need to live on rabbit food – at least not for the most part.

Regardless of which method of intermittent fasting you favour, Mattson suggests that the best way to start intermittent fasting is slowly – very slowly. You can’t go from no running at all to running five kilometres a day without feeling horrid! But that doesn’t mean running isn’t good for you. It just means you have to work up to it. Mattson suggests starting intermittent fast at a rate of perhaps just one day a week for a month and then two days a week for a month, but he is confident enough to make the following statement: “You’ll find on the days when you don’t eat so much, you are more productive.”

*BDNF is Brain derived neurotrophic factor and FGF is fibroblast growth factor. Both belong to a family of neurotrophic factors.



[1] Mattson M (2015), “Why Fasting Bolsters Brain Power: Mark Mattson at TEDx Johns Hopkins University,” Ted X, retrieved 21 March 2016

[2] Walia, A (2015), “Neuroscientist shows what fasting does to your brain,” Collective Evolution, retrieved 21 March 2016

[3] Anft, M (2012), “Neuroscience: Don’t feed your head,” Johns Hopkins Magazine, 21 March 2016

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