My Keto Experiment: From Doubt to Fat-Fueled Miles
I’ll be honest—I used to laugh off keto. I was raised on pasta-fueled long runs and carbo-loading the night before a race.
Swapping sweet potatoes and rice for bacon and avocados? Sounded like a joke.
But I was in a rut.
A few kilos heavier after the holidays, sidelined with a minor injury, and feeling like I’d lost my spark.
Some of my friends swore keto helped them drop fat fast, so I figured, screw it—let’s give it a go.
So what is keto, really?
In short: it’s flipping your body’s fuel source. Instead of running on carbs (glucose), you teach your body to burn fat.
That means loading up on healthy fats, getting just enough protein, and keeping carbs so low it makes your brain panic a bit.
We’re talking 70–75% of your calories from fat, 20% protein, and less than 5–10% carbs—usually under 25 grams a day.
That’s right, one banana could blow your daily limit.
Sounds harsh? It is. But there’s legit science behind it.
When carbs disappear, your liver starts turning fat into ketones, and those become your main fuel source instead of sugar.
The Early Days: Foggy Brain, Lead Legs
That first week was rough.
I ditched my go-to oatmeal and started eating cheese omelets with spinach drowning in olive oil.
By mid-morning I felt foggy, slow, and kind of cranky.
Welcome to keto flu—your body’s tantrum when you cut off its sugar supply.
I still remember one brutal 5K in the Bali heat that week. I had planned on doing 10K, but I was dragging. Legs felt like I was running through wet cement.
I almost gave up on keto right there.
But I didn’t.
I knew this part was temporary. I stuck with it, kept running through the sluggishness, and waited for the switch to flip.
And then… it did.
About three weeks in, I went out for an easy run.
A few miles in, something clicked. I wasn’t tired. I felt smooth. No energy dips, no need for a gel.
Just steady fuel from my own body fat.
It felt like I’d unlocked cruise control.
I ran longer than I’d planned that day.
Fat-Adapted & Flying
Turns out, this is what fat-adaptation looks like.
Your body becomes a fat-burning machine. No sugar crashes, no constant snacking. Just steady energy that feels almost too good to be true.
And I’m not alone.
Runners on Reddit shared similar stories—struggling at first, but eventually being able to run longer, even right after dinner.
One guy said he “runs longer and doesn’t crash anymore.” Another said he could just sip water and go.
That was my experience too—no gels, no bonks.
Just water, electrolytes, and the road.
What’s Happening Behind the Curtain?
By week four, I was likely in full ketosis—meaning I had a decent level of ketones in my bloodstream.
My muscles were now running on fat. Even my brain had switched gears.
And yeah, the fat started dropping.
I lost 5 kilos (around 11 pounds) in the first six weeks—and it wasn’t just water.
I saw it in the mirror. I felt it on the climbs.
Science backs this too.
A well-structured keto diet can lead to big fat loss while keeping muscle intact, especially in the short term.
Some studies even show that long-distance athletes on keto can burn fat at insanely high rates—way beyond what carb-reliant runners can.
For endurance stuff, like long runs or ultras, that’s gold.
But Here’s the Catch…
Sprints and high-speed stuff? Not so much.
One study showed that 5K performance took a hit—about a 5% slowdown—after switching to keto.
I felt that myself. My hill sprints sucked. That extra kick I had in intervals? Gone.
So yeah—if your main goal is to crush a 5K or break a PR in a fast race, keto might not be your best friend in-season.
But for me? At that moment?
I wasn’t chasing speed—I was trying to rebuild my engine and lose weight.
And keto helped me do just that.
Mental Shifts, Food FOMO & Social Sacrifices
Let’s not sugarcoat it—keto is socially weird.
I skipped out on Bali’s legendary nasi campur and mango smoothies.
My friends would sip cold Bintangs while I picked chicken off satay skewers and drank coconut water like a monk.
It tested my willpower daily.
But the payoff?
Clothes fit better. I dropped a size. My face leaned out.
My injured joints felt less beat up with every step.
Even my physio noticed the reduced inflammation.
Ditching sugar and processed carbs made a real difference in my recovery.
That’s when I started realizing—food isn’t just calories.
It’s information. It tells your body how to feel.
Final Thoughts
By the end of my keto test run, I wasn’t some keto preacher yelling “This is the one true way!”
But I became a cautious fan.
I’d seen the benefits with my own eyes and legs.
And I’d also felt the trade-offs.
The big question now: Is keto right for you as a runner?
That depends on your goals.
And that’s exactly what we’ll break down next—the real pros and cons, and how to make keto work for your running if you decide to give it a shot.
Quick Check-In:
Ever tried keto while running?
How did it go?
Drop a comment and let’s swap battle stories. 🥑🏃♂️