Autophagy has been linked to several health benefits, according to researchers. Researchers also believe that fasting can induce autophagy.
However, remember that much of the autophagy research is still in its early stages.
This article defines autophagy and its potential health benefits. It also discusses its relationship to fasting and its difference from ketosis.
Autophagy Defined
Trillions of cells make up a person’s body. Unwanted molecules can accumulate inside the body over time, causing damage to some of their parts. (1)
According to a 2015 Nature article, autophagy is a natural process that responds to this problem. Autophagy is the process where cells eliminate unwanted molecules and dysfunctional parts. (2)

Autophagy can sometimes destroy some of these molecules and parts. At times, the cell recycles these components into new ones.
The word “autophagy” comes from the Greek word for “self-eating.” The word “auto” means self, while “phagy” means eat.
The Difference Between Autophagy and Ketosis
Many people practice intermittent fasting to lose weight and improve their health. Although ketosis and autophagy are distinct processes, both are induced by intermittent fasting. The body uses the metabolic process of ketosis to produce energy, and it uses autophagy to repair and regenerate damaged cells.
Autophagy is like a self-cleaning team that patrols your body to determine what needs to be broken down, recycled, and discarded.
Ketosis can happen while fasting, starving, exercising for an extended period, or when eating a low-carb diet. Nutritional ketosis is the term used when someone deliberately pursues ketosis for diet or weight loss.
The body can enter ketosis after 12 hours of fasting, allowing it to metabolize and burn fat. The longer you fast, the higher the level of ketones in your blood. Autophagy, which promotes cellular cleansing, is fully activated after 24-48 hours of fasting. (3)
How to Induce Autophagy?
Fasting may be an autophagy trigger. When someone fasts, they choose to refrain from eating for hours, sometimes a day, or longer. A 2018 research makes a compelling case that fasting and calorie restriction can both induce autophagy. (4)
The main inducers of autophagy are energy deficits, especially sustained energy deficits, which happen while we sleep, engage in intermittent fasting, or exercise for extended periods.

We can switch our metabolism from using glucose as our body’s energy source to using ketones when we exercise for a long time or fast for 12 hours or more. This activates the process of autophagy and positively impacts how well our mitochondria work, which are the cell’s energy-producing molecules. (5)
Unfortunately, most people do not lead lifestyles that temporarily deplete their energy storage to the point where ketones are their main fuel source, resulting in a flipped metabolic switch. Without this temporary energy depletion, our body remains fed and cannot reach the fasted state needed for autophagy to function as it should.
Benefits of Autophagy
Autophagy may provide potential health benefits. As a result, there is a great deal of research focused on ways to activate this process.
There is particular interest in finding ways to stimulate autophagy to aid in treating neurodegenerative disorders that damage cells and nervous system connections, including ways to suppress autophagy in cancer patients. (6)
Autophagy appears to be important in the immune system as well, as it cleans out toxins and infectious agents. (7)
Here are some potential health benefits of autophagy:
- Increasing cell metabolic fitness by removing damaged organelles and proteins.
- Inflammation control, slowing the aging process, and protection against neurodegenerative diseases.
- Fighting infection and boosting immunity.
Signs of Autophagy
Unfortunately, there is no simple way to measure autophagy in humans at this time. No test can determine your level of autophagy or autophagy marker that is universally recognized.
Additionally, even though autophagy is generally beneficial for most people’s health, it can occasionally be harmful if left unchecked. (8)
Here are the potential signs of increased autophagy.
Mild Hunger
Tolerating mild to moderate hunger levels is usually the first step in the process for most people. Due to the effects that lower blood glucose levels have on the hormones glucagon and insulin, a decreased appetite may eventually be a sign of increased autophagy.
Increased Bowel Movements
We all know that one of the primary ways our body eliminates waste is through bowel movements. As a result, increased bowel movements, specifically having an “extra” bowel movement during the fasting period, signify enhanced autophagy that almost no one talks about.
Metallic Taste
Another potential sign of autophagy activation is a change in breath smell to a more “metallic” scent due to the ketosis process that occurs when autophagy increases. Acetone, the ketone type that primarily causes this odor, can be avoided by brushing your teeth or chewing gum.
Eye Debris
The eyes are another sign of autophagy in action. All of us have probably experienced having debris around our eyes when waking up from a deep sleep. When we fast, the same process happens, and if we engage in certain activities while fasting, like meditation, it might be increased.
The “debris” in the corner of your eye during sleep is a combination of mucus, oil, skin cells, and other waste materials.
Side Effects
Autophagy is not always beneficial. Scientists have linked excessive autophagy to some heart issues and studies have shown that excessive autophagy may kill heart cells. (9)
According to research, inhibiting autophagy in mice may also limit tumor growth and improve response to cancer treatment. This implies that an increase in autophagy might theoretically worsen the prognosis for someone with cancer.

Bottomline
There is a lot of interest in using fasting and calorie restriction to stimulate autophagy, but the precise impact this has on humans is not well understood. Scientists do not entirely know the effects of autophagy on health, nor do they know how people can trigger it. Anyone considering making lifestyle changes to induce autophagy should seek medical advice first.
Disclaimer: This article is only a guide. It does not substitute the advice given by your own healthcare professional. Before making any health-related decision, consult your healthcare professional.
Editorial References And Fact-Checking
- Bianconi, E., Piovesan, A., Facchin, F., Beraudi, A., Casadei, R., Frabetti, F., Vitale, L., Pelleri, M. C., Tassani, S., Piva, F., Perez-Amodio, S., Strippoli, P., & Canaider, S. (2013). An estimation of the number of cells in the human body. Annals of human biology, 40(6), 463–471. https://doi.org/10.3109/03014460.2013.807878
- Marx V. (2015). Autophagy: eat thyself, sustain thyself. Nature methods, 12(12), 1121–1125. https://doi.org/10.1038/nmeth.3661
- Bagherniya, M., Butler, A. E., Barreto, G. E., & Sahebkar, A. (2018). The effect of fasting or calorie restriction on autophagy induction: A review of the literature. Ageing research reviews, 47, 183–197. https://doi.org/10.1016/j.arr.2018.08.004
- Schiattarella, G. G., & Hill, J. A. (2016). Therapeutic targeting of autophagy in cardiovascular disease. Journal of molecular and cellular cardiology, 95, 86–93. https://doi.org/10.1016/j.yjmcc.2015.11.019
- 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. https://doi.org/10.4161/auto.6.6.12376
- Jiang, Z., Yin, X., Wang, M., Chen, T., Wang, Y., Gao, Z., & Wang, Z. (2022). Effects of Ketogenic Diet on Neuroinflammation in Neurodegenerative Diseases. Aging and disease, 13(4), 1146–1165. https://doi.org/10.14336/AD.2021.1217
- Yang, Z. J., Chee, C. E., Huang, S., & Sinicrope, F. A. (2011). The role of autophagy in cancer: therapeutic implications. Molecular cancer therapeutics, 10(9), 1533–1541. https://doi.org/10.1158/1535-7163.MCT-11-0047
- Anding, A. L., & Baehrecke, E. H. (2017). Cleaning House: Selective Autophagy of Organelles. Developmental cell, 41(1), 10–22. https://doi.org/10.1016/j.devcel.2017.02.016
- Altman, B. J., & Rathmell, J. C. (2009). Autophagy: not good OR bad, but good AND bad. Autophagy, 5(4), 569–570. https://doi.org/10.4161/auto.5.4.8254