Intermittent Fasting, what is it?
Intermittent fasting is a way of eating where you cycle between periods of fasting and periods of eating.
During the fasting period, you restrict your caloric intake, either by not eating at all or eating a very limited amount of calories. N.B., water and zero-calorie beverages such as black coffee and tea are permitted.
During the eating period, you eat all your daily calories within a set time frame, and nothing outside of those hours. During this period you are encouraged to eat normally, and not binge. Some popular methods of intermittent fasting include the 16/8 method, the 5:2 diet, and eat-stop-eat.
16/8 Method
A popular starting place for intermittent fasting is the 16/8 method, where you fast for 16 hours of the day and eat within an 8-hour window.
5:2 Diet
Alternatively, intermittent fasting can be out-worked by a 5:2 diet, where you eat normally for 5 days, and then for 2 days heavily restrict your caloric intake to 500-600 calories.
Eat-Stop-Eat
A third option is Eat-Stop-Eat, where you fast for 24 hours, once or twice a week. E.g., not eating dinner one day and next eating at dinner the following day.
Intermittent Fasting: New?
Intermittent fasting isn’t new, and has been used for a long time to good effect. In fact, Egyptian inscriptions date the acknowledgment of the practice back to 3800bc "Humans live on one-quarter of what they eat; on the other three-quarters lives their doctor".
Other great brains of the past noted using fasting as a tool.
Greek Philosopher Plato (Greek Philosopher) wrote "I fast for greater physical and mental efficiency".
Author Mark Twain wrote, "A little starvation can really do more for the average sick man than can the best medicines and best doctors".
How Intermittent Fasting Works
Intermittent fasting works by putting your body in a state of ketosis, which is a metabolic state where your body burns stored fat for energy instead of glucose from carbohydrates. This can lead to weight loss and other health benefits.
Some Benefits of Intermittent Fasting
1. Weight Loss
A reduces calorie intake and an increase in fat burning, can result in weight loss [1].
2. Improved Metabolic Health
Intermittent fasting has been shown to improve metabolic health markers such decreasing blood pressure, insulin resistance, and oxidative stress [2].
3. Reduced Inflammation
Chronic inflammation has been linked to lots of health problems, e.g, heart disease, cancer, and Alzheimer’s disease. Intermittent fasting can reduce inflammation in the body [3].
4. Longevity
There is some evidence to suggest that intermittent fasting may increase lifespan and promote healthy aging [4].
5. Improved Brain Function.
Intermittent fasting may improve cognitive function, and protect against neurodegenerative disease [5].
Your Brain Function in a Fasted State
One of the keys to intermittent fasting is getting to a state of ketosis. When ketones are used by the brain, it can improve cognitive function and increase alertness. This is thought to be because ketones provide a more stable and consistent source of energy than glucose, which can fluctuate depending on the availability of food [6].
During intermittent fasting, there is also an increase in the production of a protein called Brain-Derived Neurotrophic Factor (BDNF). BDNF has been linked to improved memory and cognitive function, and is pivotal for the growth and survival of brain cells [7].
Additionally, intermittent fasting has been shown to be beneficial post traumatic brain injury, and improve cognitive performance and hippocampal proliferation of neural stems cells (an increase in neural stems cells in the hippocampus, the part of the brain that plays a major role in learning and memory) [8].
In this day and age, we are by majority blessed by regular meals and excess. Intermittent fasting takes some of that away, to perhaps how we once lived – or at least when three meals a day wasn’t the standard, and challenges our bodies in a positive manner.
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Daniel Glassbrook, PhD
Daniel is a sports scientist and researcher, currently working as the first team sports scientist for the Newcastle Falcons Rugby Club, and a postdoctoral researcher in sports related concussion at Durham University.
References
1. Harris, L., Hamilton, S., Azevedo, L. B., Olajide, J., De Brún, C., Waller, G., ... & Ells, L. (2018). Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis. JBI Evidence Synthesis, 16(2), 507-547.
2. Varady, K. A., Cienfuegos, S., Ezpeleta, M., & Gabel, K. (2021). Cardiometabolic benefits of intermittent fasting. Annual Review of Nutrition, 41, 333-361.
3. Malinowski, B., Zalewska, K., Węsierska, A., Sokołowska, M. M., Socha, M., Liczner, G., ... & Wiciński, M. (2019). Intermittent fasting in cardiovascular disorders—an overview. Nutrients, 11(3), 673.
4. De Cabo, R., & Mattson, M. P. (2019). Effects of intermittent fasting on health, aging, and disease. New England Journal of Medicine, 381(26), 2541-2551.
5. Zhao, Y., Jia, M., Chen, W., & Liu, Z. (2022). The neuroprotective effects of intermittent fasting on brain aging and neurodegenerative diseases via regulating mitochondrial function. Free Radical Biology and Medicine.
6. Longo, V. D., & Mattson, M. P. (2014). Fasting: molecular mechanisms and clinical applications. Cell metabolism, 19(2), 181-192.
7. Gómez-Pinilla, F., Brain foods: the effects of nutrients on brain function. Nature reviews neuroscience, 2008. 9(7): p. 568-578.
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