Three Doctors Fasted for 5 Days—Here’s What Happened
Fasting has been around for centuries, but what are the real 5-day fast benefits? As doctors dedicated to metabolic health, we—Dr. Steven Geanopulos, Dr. Peter Wohl, and Dr. Christopher DeCarlo—wanted to put ourselves through the challenge and see what happened—not just physically, but mentally and emotionally as well. No coffee, no supplements, just water. Here’s what we experienced, what surprised us, and what you need to know if you’re considering an extended fast. Watch the podcast below!
Why We Did It
The main goal of this fast was to challenge ourselves and experience firsthand the effects of prolonged fasting. While intermittent fasting has been widely adopted, multi-day fasts are a different beast. We were interested in the benefits of autophagy, metabolic reset, and how our bodies would respond to extreme nutrient deprivation.
Another key reason was that we regularly recommend prolonged fasts to our patients, especially those battling cancer. Research has shown that fasting and ketosis can help starve cancer cells, potentially aiding in treatment and recovery. By undergoing the fast ourselves, we wanted to better understand the challenges and benefits our patients might experience.
But beyond the physiological changes, this was also a test of discipline. In today’s world of abundance, it’s rare to go more than a few hours without food. Could we resist the mental urge to eat? Could we maintain our normal routines without the energy from food?
The First Few Days: Struggles and Adaptations
The first day felt like a typical intermittent fast—nothing out of the ordinary. By the evening, the real test began. Hunger pangs kicked in, and the absence of coffee led to some withdrawal headaches. For one of us, a full-blown migraine set in, lasting into day two. Our energy levels dropped, making workouts or even basic movement feel like a chore.
Interestingly, within the first few days, pains from previous injuries and surgeries flared up significantly. Old aches that had been dormant resurfaced, making movement uncomfortable. However, by day three, those pains completely disappeared, leaving us feeling lighter and more mobile than before.
By day three, our bodies started adapting. Hunger became more psychological than physical. There were moments of fatigue, but also surprising bursts of energy. Sleep was disrupted for some, while others reported waking up with an odd sense of clarity. One of the biggest mental challenges was the habitual desire to eat—reaching for snacks out of routine rather than hunger.
The Science Behind 5-Day Fast Benefits: What’s Happening in the Body?
After 72 hours of fasting, something remarkable occurs inside the body:
- Autophagy Kicks In: Old, damaged cells begin to break down and recycle, leading to cellular renewal and potential longevity benefits.
- Fat Metabolism Activates: Without food, the body taps into its fat stores, leading to an increase in ketones—byproducts of fat metabolism that serve as an alternative energy source.
- Immune System Reset: Research suggests that after five days of fasting, the bone marrow temporarily shrinks, reducing older immune cells and making room for fresh, new immune cells upon refeeding.
- Hormonal Shifts: Growth hormone and testosterone levels spike to help preserve muscle mass, even in the absence of protein intake.
Breaking the Fast: The Refeeding Challenge
After 110 hours, the moment finally came—breaking the fast. But this isn’t as simple as eating a burger and fries. Reintroducing food after a prolonged fast requires strategy. We opted for soft foods, broths, and easily digestible proteins like eggs and avocado. A previous fasting attempt ended badly after jumping straight into a Thanksgiving meal, leading to digestive distress and bacterial overgrowth.
The key to breaking a fast? Start slow. Avoid heavy proteins and fats immediately, as digestive enzymes are depleted. Give your gut time to wake up and process food again.
The Results: Was It Worth It?
Despite the initial struggles, we found immense value in this fast. Our metabolic markers showed improved insulin sensitivity, mental clarity increased, and aches and pains faded. One of us even reported a complete disappearance of an eye floater that had been persistent for months.
Perhaps the biggest takeaway wasn’t just physiological—it was mental. Realizing that we don’t need to eat every few hours was eye-opening. Fasting is as much a test of willpower as it is a biological reset.
Should You Try a 5-Day Fast?
Fasting isn’t for everyone. If you’re considering it, here are some key takeaways:
- Prepare Ahead: Ease into fasting by practicing intermittent fasting first.
- Stay Hydrated: Electrolytes can help mitigate cramps and fatigue.
- Expect Discomfort: The first two days will be the hardest, but your body will adapt.
- Break the Fast Wisely: Start with broths and easily digestible foods to avoid GI distress.
Fasting for five days was a challenge, but one we’d consider doing again. The benefits go beyond just physical changes—it’s a mental reset, a metabolic reboot, and an exercise in discipline. If you’re up for the challenge, prepare well, listen to your body, and experience firsthand what happens when you truly let your system rest and reset.
Want to learn more about optimizing your health and longevity? Visit our Blog Home Page for more expert insights. If you’re interested in working directly with Dr. G to see if you’re an ideal client, you can explore more here. Additionally, take a look at Dr. G’s supplement line for products designed to support your metabolic health at Cyrene Labs (Cyrene labs products are only available through licensed providers).
About The Author
