On Food & Wellness: Fasting 101

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Hello lovelies,

I am finally getting around to doing one of my favorite health hacks and I thought it’d be fun to share it with ya’ll! Welcome to the second installment of these blog mini-series: On Food & Wellness. This time I'm discussing fasting 101.

I’ve been experimenting with and researching different fasting techniques for the past 11 years and it’s truly been the gift that keeps on giving. From my own experiences and research, I believe fasting contains healing components all inclusive of body, mind, and spirit.

Mentally, I feel like fasting has become a way for me to more deeply connect my mind to my body, practice mindfulness, and practice pattern interruption and self-discipline. The first couple times I did fasts, I was amazed at all the different connections I had between different foods, coping skills, social interactions, and behaviors. If you're not getting to know yourself mentally through the process of fasting, you're missing out on so many extra benefits! These mental connections we can identify while fasting are fascinating to monitor as years accrue. Sometimes they change, sometimes they stay the same, sometimes we develop new ones from new experiences, and it's all such a wonderful practice in mindfulness between the mind and the body. When we go into a fast asking "how does my physical experience influence my mental experience and how does my mental experience influence my physical experience?" we are setting ourselves up for some exceptional realizations and insights into ourselves and how we work on a subconscious level.

Spiritually, I have found fasting to be extremely fulfilling as well. Making a fast into a symbolic act of devotion or sacrifice for a specific prayer, intention, or season of my life has been deeply rewarding in ways transcendent to language. If it is not already part of your practice, I invite you to contemplate and introduce a spiritual intention in your next fast and relish the richness of whatever develops out of that for you.

And as a medical student you know I gotta nerd out about all the physical benefits that come along.

Also disclaimer: this is not medical advice, and please always check with your doctor before doing a fast. For many people, there are contraindications when it comes to conditions and medications that you want to be aware of before starting.

Purported physical benefits of fasting include:

Extending life span, shifting the body’s energy source from glucose to fat, protection against lean muscle loss from aging, increased insulin sensitivity, and decreased inflammation throughout the body.

Fasting also promotes autophagy, which is our body’s way of clearing out cellular debris. It promotes mitochondrial biogenesis which basically means each cell will have a higher capacity for generating its own energy, and it also stimulates parasympathetic activation, or the “rest and digest” part of your nervous system, lowering both heart rate, blood pressure, and increasing heart rate variability.

Fasting can also reset our circadian rhythms, or biological clocks, can protect neurons from oxidative stress, increase the microbiota variation in the gut promoting gut health, and can possibly affect outcomes in cancer, obesity, diabetes, metabolic syndrome, Alzheimer’s, Parkinson’s, PCOS, and autoimmune disorders like rheumatoid arthritis amongst others.

Other important considerations:

It’s also important to note that these benefits only occur if a certain metabolic “switch” is activated, so fasting intervals usually need to be at least 12 hours. It will take less or more time as individuals vary, but 12 hours is a solid average. One study suggests if you are predisposed to gallstones, to not exceed 16 hours of fasting at a time. However, if you’re not predisposed to gallstones, alternate day fasting and intermittent fasting frequencies that exceed 12 hours of fasting seem correlated to the above benefits.

Assigned female at birth folk also have the additional consideration of timing their fasting with their menstrual cycle. Though I haven't found a study that directly gives this information, several physician experts I follow have mentioned avoiding fasting in the week leading up to and during one's menstruation. Given the fact menstruation requires a nutritive state in the body, it's possible fasting at the wrong time in the cycle could disrupt one's natural hormonal flow, but again I would need to find a source to confirm this specific information.

Fasting does not have to be such a cut and dry, all-or-nothing mentality, either. Though not associated with the above benefits, fasting of certain food groups while still continuing to eat a cleaner diet can still be considered fasting and good for your health. You can also fast from sun up to sun down, as customary in many different religious and spiritual traditions, or choose a healthy intermittent fasting schedule based on other logistics in your life. You can also restrict caloric intake to 20-30% of usual intake on fasting days and still activate the fasting benefits listed above. So as you can see, there is a decent amount of flexibility in how you can achieve a fasting state that caters to many different levels of comfort or intention.

I personally enjoy breaking periods of fasting with juices that have different cellular nutrients for different organ systems I want to support. I find my juice fasts to be spiritually cleansing, mentally fortifying, and a relaxing physical break for my GI system.

I like to do these juice fasts only a couple times a year, but I will still sometimes integrate other forms of fasting in my weekly experience. As long as it’s a good week in my menstrual cycle, I will throw in a day or two of intermittent fasting each week if I’m not going to the gym. This doesn’t happen every week, and I am also always making sure I’m listening to my body and not fasting on days when I’m extra hungry or plan on using an excess amount of energy.

I will usually add colonics and a probiotic regimen along with my juice fasts, which usually range from 3-5 days when I do them. It's an entirely separate blog post I'd love to do at a later time, but there is more and more evidence coming out on different types of gut bacteria being more symbiotic for mental health, etc. Promoting healthy bacterial growth is just as important as the nutritional content and sequencing of one's food when considering long-term health.

I’ve done fasts that ranged all the day from 3 to 13 days and at this point I don’t see any drastic shift in benefit one way or the other in length of cleanse… this is true in both the research literature I’ve looked at as well as my own personal experience. Start conservatively and make sure to listen to your body the entire time though. There are times that I’ve set out to fast longer than I ended up fasting for because my body told me it wasn’t the right time. You are not undisciplined for listening to and respecting the messages you receive from your body.

We still have a LOT of research to do on this topic to fully understand the effects of fasting and to further confirm and clarify everything I’ve mentioned, but so far what we’ve found is pretty cool, don’t you think? If you would like a list of scientific sources to explore this more, see my bibliography below. Many of these articles are free on google scholar.

Bibliography

Anton SD, Moehl K, Donahoo WT, et al. Flipping the Metabolic Switch: Understanding and Applying the Health Benefits of Fasting. Obesity (Silver Spring). 2018;26(2):254-268. doi:10.1002/oby.22065

Choi IY, Lee C, Longo VD. Nutrition and fasting mimicking diets in the prevention and treatment of autoimmune diseases and immunosenescence. Mol Cell Endocrinol. 2017;455:4-12. doi:10.1016/j.mce.2017.01.042

de Cabo, R. , & Mattson, M. P. (2019). Effects of intermittent fasting on health, aging, and disease. The New England Journal of Medicine, 381(26), 2541–2551. 10.1056/NEJMra1905136

Elmajnoun, H. K., Faris, M. E., Uday, S., Gorman, S., Greening, J. E., Haris, P. I., & Abu-Median, A. B. (2021). Impact of COVID-19 on Children and Young Adults With Type 2 Diabetes: A Narrative Review With Emphasis on the Potential of Intermittent Fasting as a Preventive Strategy. Frontiers in nutrition, 8, 756413. https://doi-org.proxy.pnwu.org/10.3389/fnut.2021.756413

Gudden J, Arias Vasquez A, Bloemendaal M. The Effects of Intermittent Fasting on Brain and Cognitive Function. Nutrients. 2021;13(9):3166. Published 2021 Sep 10. doi:10.3390/nu13093166

Guo J, Bakshi V, Lin AL. Early Shifts of Brain Metabolism by Caloric Restriction Preserve White Matter Integrity and Long-Term Memory in Aging Mice. Front Aging Neurosci. 2015;7:213.

Janssen H, Kahles F, Liu D, et al. Monocytes re-enter the bone marrow during fasting and alter the host response to infection. Immunity. 2023;56(4):783-796.e7. doi:10.1016/j.immuni.2023.01.024

Kumar V, Evans LC, Kurth T, et al. Therapeutic Suppression of mTOR (Mammalian Target of Rapamycin) Signaling Prevents and Reverses Salt-Induced Hypertension and Kidney Injury in Dahl Salt-Sensitive Rats. Hypertension. 2019;73(3):630-639. doi:10.1161/HYPERTENSIONAHA.118.12378

Li C, Xing C, Zhang J, Zhao H, Shi W, He B. Eight-hour time-restricted feeding improves endocrine and metabolic profiles in women with anovulatory polycystic ovary syndrome. J Transl Med. 2021;19(1):148. Published 2021 Apr 13. doi:10.1186/s12967-021-02817-2

Longo V.D., Panda S. Fasting, Circadian Rhythms, and Time-Restricted Feeding in Healthy Lifespan. Cell Metab. 2016;23:1048–1059. doi: 10.1016/j.cmet.2016.06.001.

Mindikoglu AL, Abdulsada MM, Jain A, et al. Intermittent fasting from dawn to sunset for 30 consecutive days is associated with anticancer proteomic signature and upregulates key regulatory proteins of glucose and lipid metabolism, circadian clock, DNA repair, cytoskeleton remodeling, immune system and cognitive function in healthy subjects. J Proteomics. 2020;217:103645. doi:10.1016/j.jprot.2020.103645

Paoli A, Tinsley G, Bianco A, Moro T. The Influence of Meal Frequency and Timing on Health in Humans: The Role of Fasting. Nutrients. 2019;11(4):719. Published 2019 Mar 28. doi:10.3390/nu11040719

Qian J, Fang Y, Yuan N, et al. Innate immune remodeling by short-term intensive fasting. Aging Cell. 2021;20(11):e13507. doi:10.1111/acel.13507

van NK, Rusli F, van DM, et al. Behavioural changes are a major contributing factor in the reduction of sarcopenia in caloric-restricted ageing mice. J Cachexia Sarcopenia Muscle. 2015;6(3):253–68.

Zou, Z., Tao, T., Li, H. mTOR signaling pathway and mTOR inhibitors in cancer: progress and challenges. Cell & Bioscience. 2020; 10(31).

https://www.health.harvard.edu/staying-healthy/4-intermittent-fasting-side-effects-to-watch-out-for#:~:text=Skipping%20meals%20and%20severely%20limiting,than%2Dnormal%20periods%20of%20fasting.