Fasting and health

Fasting and health

Fasting and its effect on brain activity

To start, let us think of the last time you had a huge meal. How did you feel after it?.

I am sure the feeling wasn’t one of complete mental wakefulness, and much less a sharpening of your senses.  This situations are usually followed by grogginess and lack of will to do any kind of activity.

This is because once you are satiated your body turns its focus from all other activities, towards just processing the food you ate.

This implies a few changes at the physiological level, among them an increase of blood flow and as such, of oxygen supply, to the organs in charge of processing the food. Which in turn implies a reduction in the supply of oxygen which means, usually a reduction of activity of organs such as the brain.

As well as changes at the metabolic level, since as we have seen all meals imply an increase in insulin levels and such increases are known to reduce the activity of other hormones such as the human growth hormone, known for its impact in mental sharpness.

As we saw in the ancestor’s metaphor, fasting induces a more alert state. This is due to the fact that if your body »knows» it is in a state of caloric restriction, it tries to sharpen your sense. This strategy our body follows is its way to keep you from missing any possible chance of acquiring food.

And many studies have shown that none of the usual parameters studied to monitor mental acuity show impairment in a fasting state. Neither, the sustained attention, nor intentional focus, nor immediate memory showed a decline.1 2

Fasting has also been shown to improve motor coordination, learning and memory in rats undergoing intermittent fasting. And not only that, but they also showed an increase in the release of the brain-derived neurotrophic factro(BDNF) hormone known to induce the growth of neurons and for its importance in long term mermory.3

This is an incredibly interesting discovery, as this hormone was known to be produced mostly when doing exercise, and the fact that it isn’t limited to exercise but can also be induced by fasting could give us the opportunity to use both to maybe multiply the effects we could get.

Fasting and age

The Role Of

Programmed Cell Death

The relationship between aging and fasting doesn’t limit itself to this, but also affects the so called senescence process. Senescence, also known as programmed cell death, is the process by which a cell is »destroyed» after a certain amount of time has passed. This process is useful due to the fact that as a cell keeps on dividing and giving rise to new cells these cells keep on accumulating DNA damage

The accumulation of this DNA damage keeps building up until a point in which the cells lose the proper functionality and can end up multiplying without control which  could  induce diseases such as cancer. You could think of it as a building up a possible cancer cell storage.

By having a PRD (programmed cell death), we can reduce the possibility of this happening, as after a certain amount of time the cells would »die» and as such we could prevent any possible problems associated with this.

The problem is that this mechanism isn’t 100% fool proof, since many different factors such as diet and environment can give signals that mess up the cell and keep it from going into this programmed death.

Some of the factors that can inhibit PRD, are increased levels of glucose and insulin. This effect is due to the mTOR pathway, a metabolic pathway that is related to nutrient availability. The presence of insulin and glucose activate this pathway and this in turn inhibits different processes that could induce PRD.

This means that most likely, whenever we eat we are inhibiting this process, and while this isn’t a problem in the short term, the accumulation of cells that present defects could induce cancer or other age related diseases.

And, on the other hand, if we fast, and as such keep lower levels of glucose and as such of insulin. We can induce the activity of the mTOR pathway and induce programmed cell death. This triggers an elimination of old cells ( the body usually marks those cells in certain ways) and as such a reduction on that possible cancer cell store.4

This is especially true because the use of fats as a source of energy doesn’t activate the mTOR pathway and as such fasting would keep us active, with sharper senses, while at the same time helping us reduce the »possible cancer cell store».5

Edited by

Salim Garcia

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Consult a doctor before doing anything in this article.The material in this article is for informational purposes only. As each individual situation is unique, you should use proper discretion, in consultation with a health care practitioner, before undertaking the diet in this article. The author  expressly disclaims responsibility for any adverse effects that may result from the use or application of the information contained in this article.


  1. Lieberman, H. R. et al. A double-blind, placebo-controlled test of 2 d of calorie deprivation: Effects on cognition, activity, sleep, and interstitial glucose concentrations. Am. J. Clin. Nutr. (2008). doi:10.1093/ajcn/88.3.667
  2. Caloric restriction in elderly humans improves memory. Neuroscientist (2009). doi:10.1177/1073858409354691
  3. Mattson, M. P. Energy intake and exercise as determinants of brain health and vulnerability to injury and disease. Cell Metabolism (2012). doi:10.1016/j.cmet.2012.08.012
  4. Pópulo, H., Lopes, J. M. & Soares, P. The mTOR signalling pathway in human cancer. International Journal of Molecular Sciences (2012). doi:10.3390/ijms13021886
  5. Yang, Z. J., Chee, C. E., Huang, S. & Sinicrope, F. A. The Role of Autophagy in Cancer: Therapeutic Implications. Mol. Cancer Ther. (2011). doi:10.1158/1535-7163.MCT-11-0047

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