Intermittent Fasting and Brain Health

Via the Guardian: "Fasting for regular periods could help protect the brain against degenerative illnesses ... Researchers [had] found evidence which shows that periods of stopping virtually all food intake for one or two days a week could protect the brain against some of the worst effects of Alzheimer's, Parkinson's and other ailments. ... 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. ... have also worked out a specific mechanism by which the growth of neurons in the brain could be affected by reduced energy intakes. Amounts of two cellular messaging chemicals are boosted when calorie intake is sharply reduced. ... These chemical messengers play an important role in boosting the growth of neurons in the brain, a process that would counteract the impact of Alzheimer's and Parkinson's. ... The cells of the brain are put under mild stress that is analogous to the effects of exercise on muscle cells. The overall effect is beneficial. ... The link between reductions in energy intake and the boosting of cell growth in the brain might seem an unlikely one, but [there are] sound evolutionary reasons for believing it to be the case. ... When resources became scarce, our ancestors would have had to scrounge for food. Those whose brains responded best - who remembered where promising sources could be found or recalled how to avoid predators - would have been the ones who got the food. Thus a mechanism linking periods of starvation to neural growth would have evolved." You might recall that intermittent fasting and straight calorie restriction depend on different sets of genes in mice, suggesting that they are not working to enhance health in the same ways - this latest research tends to reinforce that view.



Was anyone able to track down the citations for this? I spent 20 minutes trying, and all I got were some old studies from like 2003 and 2004.

Posted by: gwern at February 21st, 2012 8:08 AM

This is a subject which interests me a great deal, I wish there was some actual data reported, and I am confused as to how the data was obtained. But it is good to see that the less than impressive testing of intermittent fasting on rats and such has not discouraged testing on humans. I am disappointed that they hedged the 'fast' to allow 500 calories per day, quite a lot IMO for a sedentary 70 year old. I am disappointed there was no discussion of the role of autophagy during the fast. I do not agree with the evolutionary biology explaination. FWIW, I fast one day (20-22 hours, water only, ending with an hour of cardio) a week.

Posted by: JohnD60 at February 21st, 2012 10:47 AM

I find the Guardian article (can't attest to the underlying research) frustratingly vague. Does growth mean neurogenesis? Are the cell bodies of neurons getting bigger? Are they extending more processes?

Swelling of neuronal cell bodies could even be construed as a negative outcome. Anything that elicits a stress response in the brain is a little bit dodgy in my opinion, since the brain seems to be vulnerable to small, cumulative stresses. I wish they could focus on the mechanism rather than totally unsubstantiated and unscientific adaptationist storytelling. If it's possible to disentangle the effects, a growth promoting response would probably be more helpful without any accompanying cellular stress. It would be best to find out what growth promoting signals are being emitted and induce those directly.

Posted by: Jose at February 21st, 2012 3:22 PM

As any avid reader of this blog and the research at large knows, intermittent fasting doesn't extend lifespan (only healthspan). Calorie restriction is the only known mechanism to extend lifespan. Thus, their idea that intermittent fasting is superior to calorie restriction is incorrect (and bias on their part likely played a role in their suggestion).

I understand. Who wants to calorie restrict for their entire life if even better benefits can be achieved through fasting only occasionally. Unfortunately, such is not the case.

Posted by: Scott at February 25th, 2012 2:57 AM

See tonight's (6 Aug 12) BBC Horizon documentary "Eat, Fast and Live Longer" Very informative and eye opening. Fasting may not make one live longer but it promotes cell renewal and neuron growth, which in turn reduces the risk of age related diseases and promotes brain health... I don't want to live forever but would like to live to a grand old age without dementia and without counting every calorie and to enjoy food. Certainly seems a good way forward and plan to start IF straight away.

Posted by: Libby at August 6th, 2012 2:26 PM
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