Popular fitness YouTuber Will Tennyson recently decided to test the limits of his relationship with food by embarking on a 72-hour water fast.
His mission? To experience the much-hyped benefits of autophagy, mental clarity, and cellular regeneration that fasting advocates claim.
What he discovered was far more profound than he expected—a journey that pushed him physically, mentally, and emotionally in ways he never imagined.
From grocery store torture to spiritual awakening, Tennyson documented every high and devastating low of his three-day fast.
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The Last Supper Strategy
Tennyson kicked off his fast with strategic intent. His final meal before the 72-hour countdown began was a massive steak paired with eggs—high in fat and protein to maximize satiety throughout the ordeal.
For this meal, I intentionally went higher fat and higher protein for higher hopes of satiety throughout the video. And I also just want to limit the carb withdrawals cuz those are going to be really bad.
He deliberately avoided carbs to minimize withdrawal symptoms, knowing full well what lay ahead.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
At 4:30 p.m. on Monday, he took his last bite. The fast had officially begun, and there was no turning back until Thursday at the same time.
Phase One: Breaking Down the Body
The first 24 hours were relatively smooth sailing. Tennyson already practiced intermittent fasting daily, so skipping breakfast felt routine.
By morning, his weight had dropped 4.9 pounds—mostly water weight—and his readiness for what came next was a mix of excitement and nervous anticipation.
Autophagy: The Body’s Cleanup Crew
One of Tennyson’s primary goals was to trigger autophagy, a cellular process where damaged cells are broken down and recycled for energy. This mechanism has been linked to anti-aging benefits, improved immune function, and longevity.
According to fasting research, autophagy typically kicks in after 24 to 48 hours without food. During this phase, your body shifts from using glucose to burning stored fat for fuel—a metabolic state called ketosis.
Tennyson used ketone test strips to track his progress. On day one? Nothing. His body was still acting like food was coming.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Grocery Store Temptation
Around hour 26, reality hit hard. Tennyson found himself in a grocery store—a masochistic choice he immediately regretted.
I walked past the bakery like it’s an ex I broke up with on Christmas. I didn’t stop or make eye contact. I just quietly made my way towards the drinks.
He stocked up on sparkling waters, electrolytes, herbal teas, and decaf coffee—anything to distract his stomach and keep his mind occupied.
His game plan was simple: stay busy or starve thinking about food. Free time was the enemy.
The Descent Into Hunger Hell
By hour 26, Tennyson hit his first major crash. Hunger ambushed him out of nowhere, and irritability set in fast.
I’m irritable and moody. I’m irritated with how irritated I am. I think I’m going to bark at somebody if they walk by me.
He second-guessed everything—his commitment, his sanity, even whether fasting had stolen Dr. Sten’s hairline. But he powered through, reminding himself that fasting has highs and lows, and the lows can feel unbearable.
For dinner, he sipped herbal tea and sparkling water. “Sophisticated starving,” he called it.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Day Two: Ketosis and Clarity
Morning two brought a dramatic shift. Tennyson woke up feeling incredible.
At almost 40 hours fasted, his body had entered full ketosis. His Oura Ring readiness score was off the charts. He felt calm, present, and laser-focused.
All of my senses are heightened right now. Like I heard a train at 5:00 a.m. that I’ve never heard before. I told Katie and she’s like, ‘It happens every morning.’ This was the first time I heard it.
His hunger levels dropped to a 2 or 3 out of 10. He didn’t need food—he just acknowledged he could eat. The mental fog had lifted entirely.
Training Heavy on Empty
At 43 hours fasted, Tennyson did something most would consider insane: a heavy leg workout.
Experts recommend continuing resistance training during extended fasts to minimize muscle loss. Tennyson wasn’t sure if that was sound advice or survival of the fittest, but he went for it anyway.
Surprisingly, the workout felt amazing. His joints felt looser, his focus sharper, and he hit his top set on the pendulum squat easier than the previous week.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
I felt more aggressive, more willing to push harder and stay in that uncomfortable place during the set.
He also noticed he could tolerate lactic acid buildup better, pushing through the burn longer than usual. His face didn’t flush as red post-set, and despite having zero fuel in his system, he achieved a solid pump.
This aligns with research showing that human growth hormone production can increase by several hundred percent during fasting, potentially aiding muscle preservation and recovery.
The Second Crash: Keto Flu Strikes
The euphoria didn’t last. By hour 49, Tennyson spiraled hard.
He was likely experiencing the “keto flu”—a phase where glycogen is fully depleted and the body transitions entirely to fat oxidation. Symptoms include headaches, irritability, fatigue, and intense cravings.
I want to raid the fridge so badly and I can’t even make a thought. Like I’m just I just feel like I’m existing at this point.
In a moment of questionable judgment, he made dinner for his wife—calling it “exposure therapy.” He plated her salad with what he described as “restraint and envy” instead of love.
His own dinner? Blueberry ginseng tea, electrolytes with ice for “hardness,” and sparkling water for dessert.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Day Three: Peak Autophagy and Spiritual Vibes
By morning three, Tennyson was deep in phase three: full ketosis and peak autophagy.
His ketone strip showed moderate ketosis—a clear sign his body was burning fat as primary fuel. His weight dropped to 188.7 pounds, over 10 pounds lighter than when he started.
But the physical changes were only part of the story.
I just feel the most alive that I’ve ever felt. Just so present in this moment. I’m just so aware of all my surroundings.
Tennyson described a sense of detachment—not numbness, but hyper-awareness. He could stare at a wall with laser focus. Time moved differently. He noticed beauty in mundane things, like red lights.
He also reported zero joint pain or soreness after his brutal leg workout—a potential benefit of reduced inflammation during fasting.
The Emotional Shift
Rather than train again, Tennyson chose rest. He got a massage, spent time reflecting, and allowed himself to just be.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
When you remove something as basic as food, your brain starts noticing things it normally ignores. The fact that I can just get in the car and go somewhere. The fact that I even have food waiting for me when this is over.
Fasting humbled him—not through suffering, but by reminding him how abundant his life truly was.
Breaking the Fast: A Sacred Moment
At exactly 72 hours, Tennyson broke his fast with bone broth, three eggs, and roasted potatoes.
He avoided the temptation to binge, respecting the work autophagy had done. Breaking a fast gently is crucial—reintroducing food slowly helps prevent digestive distress and allows your system to readjust.
I have this feeling inside my body right now like I’m being saved from something. Wow. Oh, that is so flavorful.
Every bite felt transcendent. His hands shook. His mouth watered uncontrollably. Chewing became a skill he had to relearn.
The relief and gratitude were overwhelming.
Results: What Changed
Tennyson lost 10.2 pounds over 72 hours—mostly water weight, though some fat loss occurred. His physique appeared leaner, less bloated, and more defined.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
His skin looked smoother with a more even tone, supporting claims that fasting can improve complexion by reducing inflammation.
But the real transformation was mental and emotional.
Two Major Lessons
- Food obsession is real. Tennyson realized how much of his life revolved around eating. Meals dictated his schedule, his mood, his energy. Removing food forced him to confront that dependency.
- Life is beautiful in small moments. Fasting slowed him down. It cleared mental clutter and allowed him to notice simple beauty he’d been ignoring—gratitude for movement, freedom, and abundance.
I’d honestly recommend every single one of you try this at least once.
Should You Try a 72-Hour Fast?
Extended fasting isn’t for everyone. It requires careful preparation, proper hydration, and listening to your body.
Benefits may include:
- Enhanced autophagy and cellular repair
- Increased mental clarity and focus
- Reduced inflammation
- Improved insulin sensitivity
- Fat loss and metabolic flexibility
Potential risks:
- Electrolyte imbalances
- Muscle loss if not paired with resistance training
- Fatigue, headaches, and irritability
- Not suitable for pregnant women, those with eating disorders, or certain medical conditions
If you’re curious, start with shorter fasts (16–24 hours) and work your way up. Always consult a healthcare professional before attempting extended fasting.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Final Thoughts
Will Tennyson’s 72-hour fast wasn’t just a physical experiment—it was a mental and emotional reset.
He emerged leaner, clearer, and more grateful. Whether fasting is the key to eternal health remains debatable, but one thing’s certain: it forced him to slow down, appreciate simplicity, and confront his relationship with food.
And sometimes, that’s the most powerful transformation of all.
