My personal take has usually been that fasting benefits tend to be quite overstated around the internets (I don't believe they're a miracle) and that an individual is better off learning lifelong dietary habits and healthy eating habits to maintain health in the long-run. I also believe that more long-term studies are needed to fully flesh out the human health effects (too many rat studies) and I question the dietary adherence in the long-run...Though this is not to be confused with intermittent fasting (short-term eating windows) which can mostly be stuck to of course. As a matter of fact, anyone who skips morning breakfast has been habitually doing "intermittent fasting."
This doesn't negate the fact that I do believe that fasting can be a powerful tool to use on an occasional basis. Sometimes a short-term boost in a diet (such as complete fasting) can help reset one's taste buds and build stress resilience in a longer-term diet (dealing with feelings of hunger). Confidence is built when one recognizes they won't starve to death after not eating for 24 hours - then the subsequent long-term diet can then be followed with better adherence with dealing with hunger. This seems to be what the pros are recommending as well.
Emerging evidence has been piling up for a while now especially in regards to the benefits of caloric restriction and fasting on anti-aging and fighting most modern metabolic diseases. I've witnessed the paradigm switch over a decade from a recommendation that many small meals should be eaten in a day (don't fast at all!) to the Warrior Diet being the first to claim fasting benefits (it was controversial at the time) and now seeing intermittent fasting (but not total fasting) recommended in the mainstream.
Authorities such as Dr. Valter Longo (Professor of Gerontology and Biological Sciences and Director of the Longevity Institute at the University of Southern California), Dr. David Sinclair (Professor in the Department of Genetics for Biology of Aging Research at Harvard Medical School), Neal Barnard, MD (Professor of Medicine at the George Washington University School of Medicine), and many others are making recommendations that short-term fasting periods can have long lasting health benefits related to the suppression of some cancers, glucose and diabetes control and prevention, fat loss, cognitive benefits, anti-aging, etc. I've wondered myself if doing the occasional 3-5 day fast once or twice a year can destroy any emerging cancer cells through stem cell regeneration & autophagy. There is even some benefits to the gut microbiome...complete fasting 2x a year or so seems to be the human equivalent of an oil change.
The list of benefits really goes on. I recommend Longo's book "The Longevity Diet" for more information but I've also seen Jason Fung's book "The Complete Guide to Fasting" recommended as well. Please feel free to share any other information.
Anyhow lets get to the challenge
The challenge is a complete water fast (no calories) but zero calorie (or close to zero calorie) caffeine sources such as black coffee, green tea, etc. are allowed. Bone broth or an electrolyte source can also be taken if the calories are zero or very low <10. I recommend adding iodine or potassium salt with adequate water intake to deal with feelings of dizziness or a headache from potential electrolyte imbalances.
The majority of the benefit from fasting is coming from the switch in energy metabolism and the low states of insulin and promotion of autophagy; therefore, perfect is not the enemy of the good so no need to beat yourself up if you drink a diet coke or add a zero sugar sweetener to your black coffee (but eating a candy or snatching a few chips or what have you is considered a fail)!
Loosely based on the many podcasts I've listened to and this source:
https://en.wikipedia.org/wiki/Intermittent_fasting
I've broken the challenge up into 6 phases for aspiring challengers to break:
[ ] Phase 1: 0-4 hours (Fed State: The burning up of any food sitting in your stomach)
[ ] Phase 2: 4-16 hours (Postabsorptive state: The remaining liver glycogen reserves are used as a fuel source)
[ ] Phase 3: 16-24 hours (Fasted State: The challenging period where your body is using a mix of liver glucose and fatty acids for fuel)
[ ] Phase 4: 24-48 hours (Metabolic Switch: Ketosis and autophagy ramp up and an increase in BDNF supports brain function)
[ ] Phase 5: 48-72 hours (Full blown Ketosis: Suppression of hunger. It is important to monitor energy levels and electrolyte balance at this point)
[ ] Phase 6: 72-120 hours (Edited to add that Chaperone-mediated autophagy occurs here. The fast should be broken with a small meal at 5 days max. Further fasting beyond this point will provide diminishing returns and risk of muscle loss, lack of nutrients, and other negative health effects)
Phase 1 and Phase 2 should be very easy as it can be mostly accomplished by finishing dinner early and taking a long sleep before the next day. So for instance, if you start fasting at evening 9pm, then you should have Phase 1 and Phase 2 complete by the next afternoon at 1pm. The challenge ramps up here if you're not used to hunger and skipping lunch, but 8 hours after that at 9pm again then phase 3 will be complete. Get through the night without snacking and by next morning at 9am (36 hours total), the hardest part of the challenge should be over with. Then its a matter of seeing if you can hang on every 24 hours until 5 full days of fasting is complete.
A few additional tips and points:
1.) Pro-tip: Many anecdotally have reported that the hardest part is usually the first 24 hours - 36 hours before the body switches over to complete ketosis where suppression of hunger and mental clarity begins. So I would say to focus on getting over this hump as a way to remain positive.
2.) From what I've gathered, the benefits of fasting is stated to be exponential up to 5 days so, if you can, challenge yourself for all 5 days
. The challenge ends at 5 days because after that point there is diminishing returns and potential negative effects from lack of nutrients.3.) You can certainly take daily multi-vitamins, electrolytes, vitamin d, caffeine and such if you so desire.
4.) A medium to high-intensity workout during the first 16 hours of the fast can help deplete glycogen stores and get a person into a ketosis state faster. Definitely worth considering.
5.) Do a lot of walking in the complete fasted state for additional fat loss.
Last point and a disclaimer - Lemur is not a medical professional and cannot be sued.
I'm personally aiming to complete Phase 5 (I started 9pm on December 28) of this challenge.
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