Challenges

I Ate Nothing But Sardines for 3 Days — Here's What Happened

The sardine fast is a new health trend where you only eat sardines and drink water, tea, and/or black coffee for a set number of days.

Maybe sardine fest is more accurate.

I first heard about it from Nick Norwitz's video, "I Ate 1000 Sardines in a Month...Here's What Happened."

But I didn't get the urge to do it until I listened to Dr. Dom D'Agostino describe the metabolic and health benefits of a three day sardine fast.

Dr. Dom mentions that a three day sardine fast can:

Enhance Autophagy – By keeping insulin levels low and suppressed, the fast triggers cellular "cleanup" and protein recycling.
Aid in Weight and Fat Loss – The protocol helps target body fat, specifically aiding in the reduction of visceral fat.
Provide Essential Nutrients – Helps your body burn fat for energy while still providing the essential nutrients it needs to keep your hormones and health stable, unlike water fasting.
Reduce Inflammation – Sardines are rich in omega-3 fatty acids (DHA and EPA), which help suppress systemic inflammation.

The benefits sound almost too good to be true. But I had a few reasons to find out for myself.

I've been dealing with achy joints, scalp inflammation, and a bit more fat than I'm used to.

I also tried sardines for the first time a year ago and it turns out I like them.

This fast sounds like a great way to address my issues, reset my body, and get back on the right path.

All the pieces are in place, time to give this a try.

My Plan for the Sardine Fast

My plan for the fast is simple:

Do it for 72 hours
Buy at least 4 tins of sardines in extra virgin olive oil for each day (they taste better to me this way)
Only drink water (add electrolytes)
Continue to take my daily supplements (D3/K2, Lugol's Iodine, Magnesium)
Only eat sardines outside (otherwise my pregnant wife will kill me)

My plan is in place, time to buy some sardines.

I float over to my nearby organic shop, buy all of their sardines, and they look at me like I'm a sardine while they scan each box. They knew something fishy was afoot.

Alas, I have what I need and mentally prepare to start the next day.

The First Day

Day 1 was easy.

Morning: Ate 1 tin upon waking.
Afternoon: Ate 1 tin at 3pm. Very hungry by the time I ate.
Evening: 1 tin for dinner.
Energy pattern: Full of energy throughout the day with little to no brain fog.
Body:
- Feeling light, moving seamlessly
- No notable issues
Training: Easy kettlebell workout between lunch and dinner to break a sweat
Sleep: ~7 hours, deep and good quality. Went to sleep at 11pm; woke up a couple times from my 13-month-old rolling around
Total intake: 3 tins

The Day of Struggle

Day 2 was the toughest.

Morning: Woke up very hungry. Ate 2 tins for breakfast.
Midday: Ate 2 tins for lunch. Became sluggish from early afternoon until around 6pm.
Intervention: Drank more water with salt; slowly started feeling better.
Evening: 1 tin for dinner. After 6pm, energy returned big time.
Energy pattern: Mostly consistent all day apart from the afternoon sluggish window.
Body:
- Feeling lighter
- Sense that systemic inflammation is way down
- Zero scalp issues noticed
- Right hamstring (usually very tight) isn't tight
- Cold all day, especially hands and feet
Training: Easy kettlebell workout + quick infrared sauna.
Sleep: ~7 hours, deep and good quality. Same pattern as Day 1.
Total intake: 5 tins.

Last Day, Best Day

By Day 3, I developed what I call Tin Fatigue – an absolute disdain for opening tins and all that comes with that.

I never wanted to open another oil-filled, fishy tin again.

Something about opening them, trying to take the sardines out without breaking them, and making a mess really started to frustrate me.

I was so agitated with it, I considered eating nothing the rest of the day 😭.

But, that wouldn't do me any good.

Despite my tin fatigue, day 3 was the best I'd felt.

Morning: I woke up a little hungry but life kept me from eating until noon.
Midday: I ate 2 tins at noon — hunger satisfied.
Afternoon: No sluggishness at all. Energy high and consistent all day.
Evening: Ate 2 more tins at 5:30pm.
Mental state: I had a positive mindset, felt abnormally grateful, no anxiety, and was itching to keep getting tasks done. Felt great.
Energy: High and consistent — best day of the three.
Body: Cold hands and feet resolved in the second half of the day — body temperature normalized as I fully adapted to my new sardine fasted state.
Total intake: 4 tins.

Takeaways from Day 3

No afternoon crash like Day 2 — likely because salt/hydration was dialed in from the start.
Mood and drive noticeably elevated. Classic "day 3 of a fast" report where ketones are online and the body has settled into the new fuel source.
Hunger was manageable and came in clean waves rather than the gnawing Day 2 morning hunger.

Morning After (Day 4)

The day after the fast, here's how I felt.

Hunger: Noticeably down compared to normal. Didn't wake up hungry like Day 2 and Day 3.
Energy: High and clean.
Cold extremities: Fully resolved.

My plan was to slowly reintroduce foods so that I could see which ones cause some of the inflammation in my body and tingling in my scalp.

I started with a clean first meal — eggs and butter.

Later in the day, I got ahead of myself and had a lot of sourdough bread with raw honey. The itchiness and tingling in my scalp came back shortly after.

I think blood sugar spikes, wheat/gluten reaction, or a histamine response is driving my scalp and joint inflammation. Or a combination of the three.

More experimentation and time will tell.

Reflections

Wins

My scalp inflammation noticeably reduced. There was no itching or tingling.
Muscle aches and pains disappeared — right hamstring (chronically tight) loosened up
Mood elevated by Day 3: positive, grateful, no anxiety, high drive
Digestion felt amazing. Barely needed to poop — body was absorbing nearly everything I ate
Oral hygiene felt incredible. Mouth stayed clean and hydrated throughout. Honestly didn't feel like I needed to brush (still did, mainly to kill the sardine smell)
Sleep was deep and good quality throughout
Looked visibly leaner by the end — rough eyeball estimate of 5-6 lbs down, though most of that is almost certainly water weight and not tracked (weight isn't a metric I care about)
Inexpensive protocol. Sardines are one of the cheapest high-quality protein sources available

Drawbacks

Afternoon sluggishness on Day 2 (resolved with salt + water)
Less energy for workouts due to lower calorie intake
Tin fatigue on Day 3. I'll try to find glass jar sardines next time
Only had access to boneless/skinless sardines locally. Missed out on the calcium from bones and fat-soluble vitamins + collagen from skin. Would order bone-in/skin-on next time (Wild Planet, Season Brand)

Comparison to Other Protocols

Compared to water fasting, I felt much better on the sardine fast because I could actually eat. Water fasting has its place but the sardine version is far more sustainable and still delivered similar benefits. Sleep was also way better on the sardine fast.
Compared to 1 month of the carnivore diet, I felt essentially the same — same inflammation reduction, same mental clarity, same general "lightness." My sleep was considerably better than my first few days of carnivore. The only real difference was the lack of variety. Carnivore gave me ruminant meat, eggs, organs, different cuts; sardines gave me sardines. For a quick reset, the simplicity is a feature (zero decision fatigue). For anything longer, variety is crucial for me.

Going Forward

I'm going to continue eating sardines weekly as part of my regular diet (maybe not for the next few days though 😅)

I'll definitely do another sardine fast as a reset after a bad month of eating or at the first signs of sickness. It's such a powerful tool.

Next time, I'll shorten it to two days, eat a lot more sardines throughout the day, and make sure they all have skin and bones for the extra nutrients.

This fast isn't something you have to do but it's an interesting experiment. And the benefits are fun to experience. If you're looking for a way to reset and give your body a break, this may be it.