The effect of Intermittent Fasting on the brain, or Fixing My Head

This is the written version of my speech on Intermittent Fasting I prepared for my Toastmasters Club.

I know it is hard to see it when I am up here- at my most animated, full of energy and nerves, but I suffer from depression- and have done so for the vast majority of my adult life. In my last speech- and Verity would have heard it at the Westlake club- I opened up about my mental health, with the aim of de-stigmatising depression- and found doing so gave me such a sense of relief, of total acceptance of where I am mentally, but also- most importantly- a huge amount of hope that I will be able to improve on the status quo.  That the traditional fixes that I have been relying on up until now- i.e. medication, exercise, healthy eating may not be the only avenues worth exploring.

Today, I thought I would share a recent- and in my opinion- potentially completely life-changing practice I am experimenting with-

Intermittent Fasting

Yes, I see your eyes rolling- you are thinking oh golly, what an anti-climax!  All we need is another speech about another new-fangled diet!  SIGH!

But wait. Hear me out.  I am not really interested in fasting for weight loss.  Although I do believe that it does work for that.

What I am wanting to share with you today, is the potentially very important effect fasting can have on the brain. More specifically, the effect fasting is having on MY BRAIN.

I am going to firstly run you through WHY intermittent fasting could be good for the brain- the science bit; and then touch on HOW to fast- or at least, the fasting method that is working for me.

WHY fast?  It makes a lot of sense, in terms of our evolution, to assume that our ancestors would have experienced hunger a lot more frequently that we do nowadays.  No fridge, no shops, no conveniences like a toaster would have meant you would probably have aimed to have one proper meal a day.  Perhaps eating as regularly as we do nowadays is not quite what our bodies were designed for.

I stumbled on a youtube video of Prof Mark Mattson, where he is advocating intermittent fasting as an extremely effective enhancer of brain capacity, performance and probably most important for me at this stage- its positive impact on mental health issues.  He looks specifically at the positive effect it has on degenerative conditions, such as Alzheimers and Parkinsons.

But I am wanting to take this a step further today, and suggest that- certainly in my case- I am experiencing a marked reduction in symptoms of depression intermittent fasting.

What happens in the body, when you fast, is that all the glucose supplies that are stored in the liver and blood eventually become depleted and the body then switches to the burning of ketone bodies.  This is very desirable for weight loss, because we are essentially tapping into our fat stores and burning that stored energy.  But what is the impact on the brain?

This is where it gets interesting.  Prof Mark Mattson suggests that perhaps ketosis is for the brain what exercise is for the muscles- in other words, it triggers neuronal repair and growth.  He has been able to show in rats that intermittent fasting results in brain stem cells forming new nerve cells- this is known as neurogenisis- in the hippocampus of the brain.

Interestingly, the hippocampus is the area of the brain associated with learning and memory, as well as mood and emotion.  It is the part of the brain that a brain scan will show the first signs of damage from diseases such as Alzheimers- where memory loss is the first indication of the disease.  Another effect of Intermittent Fasting that has been noticed in the hippocampus, is that it increases the levels of what is known as brain-derived neurotrophic factor, or BDNF.  BDNF is best described as FERTILISER for neurogenisis.  Depression is strongly linked with low levels of BDNF in the brain.  So, it seems logical that the effect I am feeling on my mood since I have started Intermittent Fasting a few times a week, could well be as a result of the improved levels of BDNF in my brain.


In the wild, you can imagine that this mechanism was very useful.  Picture Cam the Cavewoman.  If I have not eaten for a while, being more alert, more aware with enhanced cognitive abilities triggered by ketosis, would make me more likely to have a successful hunt, or develop a new way of digging for roots, or doing whatever it takes to get my next meal.


So now the HOW of intermittent fasting.  The 16/8 method I am playing with, means, essentially, that on most days, I skip breakfast and only eat at about 1pm.  By doing this I am “fasting” for 16 out of 24 hours and only eating within an 8 hour window each day.  I also believe in eating healthy, real foods, but have always been fairly good with that- I don’t have a very sweet tooth- so that has not changed.  Those are the – very simple- mechanics of the “diet”.  I often exercise in that fasting time period, and I don’t restrict my fluids at all- drinking water, tea and coffee, but with very little milk.

In conclusion, Intermittent fasting is not new.  People have been fasting for mental clarity, spiritual enlightenment or simply because they hadn’t had a successful hunt since the dawn of human existence.  It seems to me that perhaps  my brain- and possibly yours- functions far better if it has to use ketones as fuel from time to time- thereby stimulating increased levels of BDNF, that brain fertilizer and creating new nerve cells in the important hippocampus section of the brain.

Thank you.

The very act of eating can be exhausting; it takes a lot of energy to digest food. When the body is freed from that chore, it naturally feels lighter and much more vibrant. ~Allan Cott

I fast for greater physical and mental efficiency. ~Plato






Leave a Reply

Your email address will not be published. Required fields are marked *