Fasting 101: The Hype, Science, and How-To Guide to Intermittent Fasting
From obscure diets like keto and carnivore to not eating at all, we’ve arrived at the latest health craze:
Intermittent fasting (IF)
Is abstaining from food really the path to better health and longevity?
Let’s dig in.
The Hot New 30-Day Detox...That’s Actually Ancient
While Silicon Valley biohackers and Redditors love to test-drive trendy diets, fasting has been practiced for millennia.
Nearly every major religion has some ritual of fasting—whether for spiritual clarity, penance or to align with ancient seasonal food availability.
Fasts range from the infamous 40 days Jesus spent in the desert to the Islamic Ramadan fast from dawn to sunset.
Back in the early 1900s, fasting was used as a treatment for obesity. Controversial health guru Bernarr Macfadden was a proponent of fasting, doing “raw milk fasts” for days at a time.
Today, secular fasting focuses more on potential health perks than spiritual enlightenment.
As biologist Valter Longo told the New York Times, “Fasting is easier than eating less, and it’s more effective than traditional diets."
The Science-Backed Benefits of Fasting
When the body isn't focused on digesting, it can direct energy to other repair and rejuvenation tasks. Here’s what happens during the fasted state:
Autophagy: cellular “self-eating” of damaged components (Longo and Mattson, 2014)
AMPK activation: a key longevity pathway (López-Lluch et al., 2019)
Immune system regeneration (Cheng et al., 2014)
Improved insulin sensitivity and blood sugar regulation (Arnason et al., 2017)
This helps explain why intermittent fasting shows promise for weight loss, reduced inflammation, balanced hormones, longer lifespan, and beyond.
Myth-Busting: The Downsides of Overdoing It
Don’t starve yourself forever hoping to live to 200. As with most things, moderation is key. Aggressive fasting can backfire over long periods:
Muscle loss and slowed metabolism (Zouhal et al., 2020)
Impaired thyroid and sex hormones (Heilbronn et al., 2005)
Increased cortisol stress hormone (Kroeger et al., 2012)
Aim for a gentle, sustainable protocol that leaves you feeling energized.
Finding Your Optimal Fasting Sweet Spot
I’ve experimented with various IF durations, including 20-hour fasts as a teenager.
While some short-term fasting is great, that excessive duration left me depleted without the muscle-building and recovery I needed.
These days I land on 14-15 hour fasts, typically from 8 pm through 11 am the next day. This gives me an eating window of about 9-10 hours. I’ll break the fast gently with bone broth, then eat 1-2 balanced meals through the afternoon and evening.
This allows me to maintain muscle while reaping autophagy and blood sugar benefits. I adjust my fasting duration day-to-day depending on my energy needs.
The key with any biohack is finding what works long-term for YOU. Avoid dogmatic rules. Experiment and pay attention to how different protocols affect your mood, energy, skin, sleep, and more.
Add just one step at a time, like 12 hours overnight, and build from there.
The future of health likely includes both periodic fasting AND feasting. Our ancient bodies thrive on the natural rhythms of scarcity and abundance. By working with, not against our biology, we can biohack our way to vitality.
Should You Try Intermittent Fasting?
At the end of the day, intermittent fasting is an ancient practice getting modern updates.
The science shows great promise for longevity, but you have to find the protocol that works for your lifestyle. Start conservatively with 12-14 hours and listen to your body. Pay attention to changes in energy, sleep, skin health and more to gauge results.
Be prepared for some adjustment period symptoms like hunger or irritability before adapting.
And remember—fasting should leave you feeling rejuvenated, not depleted.
Use common sense and enjoy both the feast AND the fast for long-term wellness.
With Love and Gratitude,
Jack
KH