All throughout history, humans have been no strangers to the concept and practice of fasting. When getting food was not as simple as hopping in the car for a short drive down the road, food scarcity was very real, and people often went without eating for days at a time. This feast-and-famine routine has been engrained into our evolution.

Fasting elicits an amount of stress upon the body’s cells, enough to drive some rather interesting processes. Now, we are told that we must eat every 2–3 hours; if we do not, we are warned we will suffer from low energy, lethargy, and reduced metabolism and brain function. With such mainstream ideology, we are eating more frequently now than ever before. However, the benefits to time-restricted feeding (fasting) are becoming more widely acknowledged, and the research supporting this is only growing stronger. Below are five of the many benefits of fasting.


Longevity is linked to mitochondrial function. Mitochondria are the energy-producing “power houses” within the cell, and their function is heavily linked with the aging process. A study published in 2017 found that fasting increased longevity in worms by altering mitochondrial networks.[1]

Central to longevity research is mitochondrial biogenesis, which is the proliferation of new mitochondria. In a study published in 2011, calorie restriction was found to increase mitochondrial biogenesis, offering a potential pathway to increasing longevity through fasting.[2]

In addition, fasting leads to lower insulin levels and less oxidative stress,[3] both of which are markers for longevity.


Autophagy (meaning “self” + “eating”) is the clearing of debris or toxins within cells, and mitophagy is the clearing of dysfunctional mitochondria from the cell, which is essentially a recycling process.

Fasting is known to activate this process of autophagy,[4] as is low insulin and IGF-1 (insulin growth factor) levels. Autophagy is linked to health within many of the organs. In fact, a lack of autophagy within the brain is known to induce neurodegeneration.

Weight Loss

Fasting is a viable option in the fight against obesity and the diseases that relate to it. A study found that alternate-day fasting decreased body fat percentage, total cholesterol, LDL and triglycerides.[5]

In addition, fasting for a period enables a person to plan their food environment better. For example, if a person is at work for 10 hours during the day and finds that this is a particularly notorious time for their self-sabotage, fasting throughout these vulnerable hours and eating when at home surrounded by good food options will likely lead to weight loss. The lower levels of insulin reported when fasting will also leave opportunity for greater fat oxidation throughout the day, which could also lead to weight loss.

Brain Health

Oxidative stress can wreak havoc within the brain and is under scrutiny for some of the most crippling brain disorders.[6] High levels of oxidative stress within the brain can exacerbate any damage occurring within brain cells. Fasting can result in a reduction of oxidative stress, possibly posing as a potential mechanism to support brain health.

In a recent study during Ramadan, fasting increased brain-derived neurotrophic factor (BDNF).[7] BDNF helps existing neurons survive and encourages the growth of new brain cells (neurogenesis) as well as the development of synapses (communication links between neurons).

Autophagy is another mechanism by which fasting can support brain health. Short-term fasting was found to induce profound neuronal autophagy.[8] There is continuing research in fields such as mental health and brain trauma.


An area of interest is fasting as a potential therapy in cancer. Fasting can reduce some of the side effects from the conventional therapies like chemotherapy. Furthermore, reduced IGF-1 can impact this process. One such study in mice found that a 72-hour fast reduced IGF-1 by 70% and protected against three of four chemotherapy drugs tested.[9]

A human case study in 2009 found that short-term fasting (48 hours) was protective of normal cells against high-dose chemotherapy but was not protective of cancer cells.[10] Protecting normal cells but not cancer cells from chemotherapy could mean that the impact chemotherapy has upon the rest of healthy cells in the body is limited. This, among the other benefits of fasting mentioned above, appears to be very promising in the treatment of cancer. It is worth noting that the studies in this field are rather preliminary and more evidence needs to be gathered before any definitive conclusions are reached.


Although five health benefits of fasting have been presented in this article, there are many more associated with this practice that extend even further. Be sure to check out more of our articles on the benefits of fasting and how to incorporate fasting into your ketogenic diet!


1. Weir, H. J., Yao, P., Huynh, F. K., Escoubas, C. C., Goncalves, R. L., Burkewitz, K., … & Mair, W. B. (2017). Dietary restriction and AMPK increase lifespan via mitochondrial network and peroxisome remodeling. Cell metabolism, 26(6), 884-896.

2. Cerqueira, F. M., Laurindo, F. R., & Kowaltowski, A. J. (2011). Mild mitochondrial uncoupling and calorie restriction increase fasting eNOS, akt and mitochondrial biogenesis. PloS one, 6(3), e18433.

3. Wegman, M. P., Guo, M. H., Bennion, D. M., Shankar, M. N., Chrzanowski, S. M., Goldberg, L. A., … & Anton, S. D. (2015). Practicality of intermittent fasting in humans and its effect on oxidative stress and genes related to aging and metabolism. Rejuvenation research, 18(2), 162-172.

4. Levine, B., & Klionsky, D. J. (2004). Development by self-digestion: molecular mechanisms and biological functions of autophagy. Developmental cell, 6(4), 463-477.

5. Varady, K. A., Bhutani, S., Church, E. C., & Klempel, M. C. (2009). Short-term modified alternate-day fasting: a novel dietary strategy for weight loss and cardioprotection in obese adults. The American journal of clinical nutrition, 90(5), 1138-1143.

6. Huang, W. J., Zhang, X. I. A., & Chen, W. W. (2016). Role of oxidative stress in Alzheimer’s disease. Biomedical reports, 4(5), 519-522.

7. Bastani, A., Rajabi, S., & Kianimarkani, F. (2017). The effects of fasting during Ramadan on the concentration of serotonin, dopamine, brain-derived neurotrophic factor and nerve growth factor. Neurology international, 9(2).

8. Alirezaei, M., Kemball, C. C., Flynn, C. T., Wood, M. R., Whitton, J. L., & Kiosses, W. B. (2010). Short-term fasting induces profound neuronal autophagy. Autophagy, 6(6), 702-710.

9. Lee, C., Safdie, F. M., Raffaghello, L., Wei, M., Madia, F., Parrella, E., … & Longo, V. D. (2010). Reduced levels of IGF-I mediate differential protection of normal and cancer cells in response to fasting and improve chemotherapeutic index. Cancer research, 70(4), 1564-1572.

10. Safdie, F. M., Dorff, T., Quinn, D., Fontana, L., Wei, M., Lee, C., … & Longo, V. D. (2009). Fasting and cancer treatment in humans: A case series report. Aging (Albany NY), 1(12), 988.

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