What 20 Hours of Fasting Does to Your Body: Insights from Dr. Mindy


The benefits of a 20-hour fasting period, as highlighted by Dr. Mindy, include improved cellular health, metabolic enhancements, potential mental clarity, mindfulness, and self-reflection. Read on to find out more about tapping the healing potential of our body.

Throughout human history, our ancestors often went without eating for extended periods of time, dictated by the availability of food. This pattern of fasting has been ingrained in our biology, and recent research suggests that it can have profound effects on our health.

Intermittent fasting, the practice of voluntary abstinence from food and drink has captivated the attention of researchers and health enthusiasts alike. Fasting is now experiencing a renaissance, with a surge of books and diet recommendations touting its potential benefits. While scientific evidence primarily stems from animal studies, observations of religious fasting, and small human trials, the biological advantages of intermittent fasting are becoming increasingly apparent.

Dr. Mindy Pelz, a renowned expert in women’s hormones and fasting, sheds light on the transformative effects of fasting for 20 hours and beyond.

Biological Effects of 20-Hour Fasting

20 hour of fasting
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When we fast for around 20 hours, a process called autophagy is triggered within our cells. Autophagy is a remarkable self-repair mechanism in which cells remove damaged components and recycle them for energy. Dr. Mindy explains that this extended fasting period allows the body to enter a hyperactive healing state, pushing out toxins and initiating cellular repair. Research has shown that even shorter fasting durations, such as 16 hours, can lead to significant improvements in metabolic markers like cholesterol, insulin, and hemoglobin A1C.

In a groundbreaking research report, experts delve into various intermittent fasting regimens and provide an in-depth analysis of their potential health benefits, with a particular focus on human intervention studies. Weight management and metabolic parameters associated with conditions such as type 2 diabetes, cardiovascular disease, and cancer take center stage in exploring the outcomes of interest. Additionally, the paper investigates the intricate mechanisms connecting fasting with human health, including circadian biology, the gastrointestinal microbiota, and modifiable lifestyle behaviors like diet, activity, and sleep.

One of the discussed fasting regimens is alternate-day fasting, where fasting days alternate with normal eating days. While animal studies demonstrate its efficacy in reducing fasting insulin and glucose levels, improving cholesterol profiles, and lowering cancer risk factors, evidence from human trials remains limited and encompasses small sample sizes. Though some studies have reported modest weight loss and enhancements in metabolic markers, concerns surrounding hunger and discomfort raise questions about the feasibility of alternate-day fasting as a widespread public health intervention.

Modified fasting regimens, such as the popular 5:2 diet, offer an alternative approach by allowing severely restricted energy intake on fasting days (around 20-25% of energy needs). Animal studies indicate that these regimens can reduce fat accumulation and improve metabolic markers. Human intervention studies on modified fasting reveal weight loss and mixed effects on metabolic parameters, lipids, and inflammatory markers. However, evidence is lacking to suggest that modified alternate day fasting outperforms standard energy restriction regimens.

Time-restricted feeding, another form of intermittent fasting, involves limiting the eating period to specific hours of the day, thereby extending the daily fasting interval. Animal studies highlight its potential for weight loss and improvements in metabolic markers, even without significant changes in overall energy intake. Although human studies on time-restricted feeding are limited, they demonstrate reductions in weight and some improvements in metabolic parameters. The synchronization of fasting regimens with daily circadian rhythms emerges as a crucial factor for optimal metabolic function.

The intricate mechanisms linking intermittent fasting with health include circadian biology, the gastrointestinal microbiota, and modifiable lifestyle behaviors. Aligning eating patterns with daily circadian rhythms may optimize metabolic health, while the influence of fasting on the gastrointestinal microbiota affects energy balance and metabolic function. Furthermore, intermittent fasting can shape modifiable lifestyle behaviors such as energy intake, expenditure, and sleep patterns.

Benefits of 20-Hour Fasting

The benefits of fasting for 20 hours extend beyond cellular repair. One of the most noticeable advantages is weight loss. Dr. Mindy emphasizes that the body stores excess weight as a protective mechanism, safeguarding vital organs. By engaging in fasting, we can tap into these fat stores and release the stored energy, resulting in weight loss. Additionally, fasting has been found to have positive effects on hormonal balance. People suffering from hormonal imbalances, such as insulin resistance or estrogen dominance, may find fasting to be a valuable tool for restoring balance.

What is Autophagy and How Does it Impact our Body?

autophagy and fasting
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In addition to its impact on weight management and metabolic health, intermittent fasting has gained attention for its ability to stimulate autophagy, a fundamental cellular process that plays a crucial role in promoting overall health. Autophagy, which translates to “self-eating” in Greek, is a natural mechanism by which cells recycle and remove damaged or dysfunctional components. This process is particularly activated during periods of fasting, leading to a range of biological benefits.

During autophagy, cells break down and remove intracellular debris, including misfolded proteins and damaged organelles. By clearing out these cellular waste products, autophagy helps maintain cellular homeostasis and promotes cellular health. It acts as a quality control mechanism, ensuring that only functional components remain within the cell. In this way, autophagy helps prevent the accumulation of toxic proteins and organelles, which are implicated in various diseases.

One of the key areas where autophagy’s role has been extensively studied is in neurodegenerative diseases. Conditions such as Alzheimer’s, Parkinson’s, and Huntington’s diseases are characterized by the accumulation of abnormal proteins and damaged organelles within neurons. Autophagy acts as a defense mechanism, selectively removing these harmful aggregates and promoting neuronal health. By facilitating the clearance of protein aggregates, autophagy contributes to the prevention or delay of neurodegenerative processes and the maintenance of proper brain function.

Autophagy’s involvement in cancer prevention and treatment is also a subject of intense research. Dysfunctional autophagy has been linked to an increased risk of developing certain cancers. Autophagy acts as a safeguard, preventing the accumulation of damaged DNA and mutations that can lead to the uncontrolled growth of cancer cells. Furthermore, autophagy promotes the elimination of cancer cells by enhancing immune surveillance and facilitating cell death. In this context, autophagy acts as a double-edged sword, both preventing the initiation of cancer and aiding in its treatment by sensitizing cancer cells to therapies.

Beyond its role in preventing diseases, autophagy is closely associated with longevity and anti-aging effects. As cells age, their ability to carry out efficient autophagy declines, resulting in the accumulation of cellular waste and compromised cellular function. By stimulating autophagy, fasting enhances the removal of damaged components, allowing cells to maintain their functionality and promoting longevity. Research in animal models has shown that intermittent fasting and caloric restriction, both of which induce autophagy, can extend lifespan and improve overall health.

The activation of autophagy during fasting can be attributed to several factors. One of the key regulators of autophagy is the mammalian target of rapamycin (mTOR) pathway. During fasting, the reduction in nutrient availability and insulin signaling inhibits mTOR, leading to the initiation of autophagy. Additionally, fasting promotes the production of ketone bodies, which also play a role in stimulating autophagy.

While the link between fasting-induced autophagy and its health benefits is increasingly recognized, more research is needed to fully understand the mechanisms and optimize its effects. Factors such as the duration and frequency of fasting, as well as individual variations, may influence the extent of autophagy induction. Furthermore, exploring ways to harness the benefits of autophagy without the need for prolonged fasting is an area of ongoing investigation.


Let us remember the empowering message of Dr. Mindy’s quote: “You are the miracle, not the diet.” This quote encapsulates the essence of fasting, highlighting that it is not about relying on external interventions. Instead, it is a means to reconnect with our innate ability to heal and thrive. Fasting is not just another passing trend or restrictive diet; it is an opportunity to reconnect with our natural state of being and unlock the extraordinary healing potential that has evolved within us over centuries. Fasting not only has physical benefits such as cellular health and metabolic improvements but also offers mental and emotional clarity, mindfulness, and self-reflection. It is important, however, to approach fasting with mindfulness, respect for individual needs, and guidance from healthcare professionals. Ultimately, fasting is a transformative experience that allows us to embrace the miraculous power that resides within us and embark on a journey of self-discovery, renewed vitality, and optimal well-being.


Patterson, R. E., Laughlin, G. A., Sears, D. D., LaCroix, A. Z., Marinac, C., Gallo, L. C., Hartman, S. J., Natarajan, L., Senger, C. M., Martínez, M. E., & Villaseñor, A. (2015). INTERMITTENT FASTING AND HUMAN METABOLIC HEALTH. Journal of the Academy of Nutrition and Dietetics, 115(8), 1203–1212. doi: 10.1016/j.jand.2015.02.018. PMID: 25857868. PMCID: PMC4516560. NIHMSID: NIHMS663671.

Glick, D., Barth, S., & Macleod, K. F. (2010). Autophagy: cellular and molecular mechanisms. Journal of Pathology, 221(1), 3–12. doi: 10.1002/path.2697. PMID: 20225336. PMCID: PMC2990190. NIHMSID: NIHMS251117.


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