I’ll Shoot Straight With You—Here’s My Take on Fasted Running
I ran fasted for years. Living in Bali, where mornings are steamy and I’m usually on the road by 5:30 a.m., the idea of eating before a run made me nauseous. Most days, it was just a splash of water and maybe black coffee.
I figured, hey, no fuel means faster fat burn, right?
And sometimes, it did feel amazing. Other times? Not so much—hello cramps, dead legs, and that mid-run “why am I even out here?” spiral.
So, I started digging.
Like many runners, I’d heard about the “fat burn” perks of fasted running, and I wanted to know if it actually worked—or if I was just skipping breakfast for no reason. This article is the result of that curiosity, trial-and-error, and a lot of sweaty sunrise miles.
We’ll break down:
- What fasted running really means (think 6–12 hours after your last meal)
- How it compares to fueled running (you ate a snack or meal 1–3 hours before)
- When I personally choose each option
There’s no universal answer—it all depends on your goals, your run, and how your body handles it.
🧠 Fasted vs. Fueled Running: What’s the Difference?
Fasted running means you haven’t had calories for at least 6–12 hours. That’s usually your early morning run, where your last meal was dinner the night before.
Fueled running means you’ve eaten beforehand—anything from a banana 30 minutes out to oatmeal 2 hours before.
So why does this even matter?
Running on an empty stomach can feel light, fast, and easy—no digestion issues, no prep, no delay.
But toss some fuel in the tank and you might feel stronger, more focused, and less likely to bonk halfway through.
The running world debates this constantly, and honestly, I’ve lived both sides.
Why I Sometimes Run Fasted
Even though I’m a big fan of eating before hard workouts now, I still see the value in fasted runs—if you use them right.
You’ll Burn More Fat (Short Term)
When your glycogen tank is low, your body turns to fat for fuel.
One study found that cyclists who hadn’t eaten in 7 hours burned 70% more fat (7.7g vs. 4.5g) than those who had eaten.
Other research shows similar effects when running before breakfast.
That’s great if you’re training your body to rely more on fat (like for ultramarathons). But heads-up—it doesn’t mean you’ll lose weight faster. Fat burn and fat loss aren’t the same.
It’s Super Convenient
Mornings in Bali are chaotic. The sun rises early, the traffic wakes up even earlier, and every minute before the heat hits matters.
Skipping breakfast gave me back 30 minutes of sleep and let me roll out the door without fuss. Plus, most runners I know aren’t exactly hungry at 5 a.m. anyway.
Fewer Stomach Issues
I used to load up on “healthy” food before runs—yogurt, fruit, the works. Then I’d spend the next 5 miles fighting reflux and cramps.
Running with food in your gut (especially dairy or anything acidic) can be a disaster.
When I run fasted, my stomach stays calm. Same goes for clients with IBS or reflux—most of them prefer fasted runs for exactly this reason.
👉 Quick Reddit Confession: One runner on r/running shared how switching to fasted jogs (just coffee beforehand) helped them finally run without constant stomach problems. Not a miracle cure—but they could run comfortably again.
Why I Don’t Always Run Fasted
Fasted runs sound great, but they’ve got real downsides—ones I’ve learned the hard way.
You’ll Probably Feel Slower
No surprise here: if you don’t eat, your body has to work harder—especially when you push the pace.
Research backs this up. Studies show endurance is lower on an empty stomach.
I’ve seen it in my own long runs—miles 5 through 10 always feel tougher when I don’t fuel.
It Can Burn Muscle
This one hits home.
When you wake up, cortisol (your stress hormone) is already high. Training in that state without food? It spikes even more.
That can trigger muscle breakdown, especially during longer or tougher sessions.
One study found that fasted morning runners had significantly higher cortisol.
I once did fasted intervals for two weeks straight—by the end, I felt weak and flat. My muscles were screaming for fuel. Lesson learned.
You Might Get Sloppy—and Hurt
Low fuel doesn’t just slow you down—it messes with your brain.
Coordination, focus, balance—they all go out the window when you’re running on fumes.
One Healthline article warned that fasted runners had worse focus and higher injury risk.
I once zoned out during a trail run, stumbled, and nearly faceplanted on a rock. Fatigue messes with form, and bad form leads to tweaks and tumbles.
It’s Not Safe for Everyone
This part isn’t negotiable.
If you’re diabetic, have adrenal problems (like Addison’s), or any condition that affects blood sugar, do not run fasted. It can trigger dangerous lows.
Even if you’re healthy, watch for:
- Dizziness
- Irregular heartbeat
- Extreme fatigue
Your body knows when something’s off—listen to it.
👉 Coach’s Tip
If you do run fasted, drink water first.
You’re likely waking up dehydrated, and starting your run like that will only make fatigue hit harder.
I always guzzle a full glass—sometimes with electrolytes—before I even lace up.
When Fasted Running Can Actually Make Sense
Let’s be real—fasted running isn’t some magical hack, but it’s not the devil either. If you use it smartly, it can work. I still use it in my own training from time to time, especially in these situations:
1. Short, Easy Runs in the Morning (<45 Minutes)
This one’s my go-to.
If I’m heading out for a chill 20–40-minute jog early in the morning, I usually just roll out of bed, grab some water or black coffee, and go. No breakfast.
The first mile or two always feels a bit rusty, but then I loosen up and settle into cruise mode.
These runs stay easy—Zone 1 to low Zone 2 at most. And that’s key. I’m not pushing pace or chasing a PR. Just logging miles and training the body to burn fat.
One coach I trust told me: if your run is under 90 minutes and at a conversational pace, it’s totally fine to go fasted.
Studies back that up too—fat oxidation gets a nice bump during low-intensity, fasted sessions.
Personally, I adapted to this routine after about two weeks. Now I can knock out a few easy miles on an empty stomach most mornings without a problem.
2. Fat Adaptation for Long-Distance Running
If you’re training for an ultra or a long trail race, fasted runs can be a decent tool—but only in the right phase.
When I was prepping for my first 50K trail race, I sprinkled in some mid-distance fasted runs during the base-building phase. Why? Because I wanted my body to get better at using fat for fuel.
That’s called metabolic flexibility—being able to switch between carbs and fat as needed.
Research supports it: Fasted, low-intensity workouts can make your muscles more efficient at burning fat.
On long trail days when fueling options are limited, that extra efficiency can mean the difference between grinding through mile 30 or bonking hard.
I’ll be honest—those early fasted long runs were rough. But after a few weeks, I could go farther with less food before hitting the wall.
I still brought water and sometimes a gel, but I waited longer before taking them.
3. Running While Intermittent Fasting (IF)
Some of my clients follow intermittent fasting—like the 16:8 window (no food before noon). When that’s the case, we adjust the plan.
For example, one client did two short morning runs per week on just water, but we kept the tougher sessions for after her first meal. It worked because we were deliberate about it.
If your schedule or faith includes fasting, you’ve got to plan ahead.
- Evening runners doing IF might train after dinner.
- Morning folks? Keep it short and easy if you’re going out fasted.
Don’t wing it.
🧠 Coach’s Bottom Line:
- If it’s short and easy, fasted is usually fine.
- If it’s long or hard, fuel up.
Use fasted runs on purpose—to train fat-burning or fit your routine.
Just don’t do it by accident.
When You Should Definitely Eat First
Now let’s flip the script. There are times when running fasted is a flat-out bad idea. Trust me—I’ve learned the hard way.
1. Long Runs (Over 60 Minutes)
If you’re going longer than an hour, especially at a moderate pace, you need to eat. Period.
I once made the genius move of trying to do a 10-mile progression run fasted. By mile 7, I crashed—hard. I had to walk the rest, felt awful the whole day, and swore never again.
Here’s the deal: Your body stores only so much glycogen. When that runs out, your energy nosedives.
Science backs it—long fasted runs (90+ minutes) hurt performance.
Even a small snack—a banana, a slice of toast, or an energy bar—can be enough to keep you going strong.
2. Speed Work, Hills, or Intervals
If you’ve got a workout where you plan to push—like tempo runs, hill repeats, or intervals—don’t go fasted.
You need carbs to fire at full throttle.
One study pointed out that pre-workout carbs boost prolonged performance during intense efforts.
And that checks out in my own training log. Any time I tried fasted speedwork, the result was the same:
- Sluggish legs
- Slower splits
- Miserable run
Now, I always eat beforehand—something light but effective.
- Half a bagel with honey
- A gel
- Even just a sports drink
You don’t need a buffet, just enough to prime the system.
3. Evening Runs After a Full-Day Fast
This is a sneaky one.
Let’s say you’ve had a hectic day—skipped breakfast, light lunch, maybe a delayed dinner. Now it’s 7 p.m., and you want to run.
Bad idea. I’ve been there.
I did a hard interval session after about 14 hours of fasting—just coffee all day. By the second interval, my hands were shaking. It was awful.
If you haven’t eaten all day, even an easy run can feel brutal.
For speed or long runs in the evening, please eat something.
Personal Story Time
There was this one time I made the classic rookie mistake—I scarfed down a massive BLT sandwich and then ran a 5K tempo… 45 minutes later.
Big mistake.
The cramps kicked in around mile one. I felt like I was getting punched in the gut every step. Nausea, regret, you name it.
Lesson learned: either give yourself time to digest or keep it light before the run.
I’d rather wait an extra half hour than ruin the workout.
What to Eat Before a Run (And When)
Let’s keep it simple: if you want to feel good out there, don’t just wing your pre-run meals. Here’s how I approach it—straight from what’s worked for me and the runners I coach.
If You’re Eating 2–3 Hours Before (Full Meal)
This is the sweet spot if you’ve got time. You want a solid, mostly-carb meal with a bit of protein to stay fueled—without feeling like a brick mid-run.
Think:
- Oatmeal with banana and honey
- Eggs with toast
- Rice and chicken
- Fruit smoothie with yogurt
According to the Mayo Clinic, eating carbs at least an hour before running can boost performance.
Personally? I go for a bowl of rice porridge or chia pudding with fruit—sometimes I’ll throw in a small handful of nuts.
I’ve found that eating 2–3 hours out gives your stomach time to settle so you’re not sloshing around on mile three.
💡 Target: 300–500 calories
Enough fuel without overload.
If You’ve Got Less Than 1 Hour (Quick Snack)
This is crunch time. You don’t want to skip fueling, but you also don’t want to hurl on the sidewalk.
Keep it light and all about the carbs—100 to 200 calories, tops.
My go-to options:
- A ripe banana
- Toast with jam or honey
- A small smoothie
- Dates with nut butter
- An energy gel
Me? If I’m heading out the door with 15–30 minutes to spare, I usually grab 2–3 dates or a gel. It’s just enough to get me through a 30–45-minute run.
Sometimes I’ll sip on black coffee with a little sugar—gives me a kick without weighing me down.
Emergency Fueling Mid-Run
Ever get hit with that “oh no” hunger mid-run? Happens to the best of us—especially when the route ends up longer than planned.
For long runs, I always carry a gel or a few dates. One little trick I use:
👉 Squeeze a honey packet into my water bottle.
Sip on that mid-run and it’s like flipping the power switch back on.
But if I’m caught empty-handed?
I slow down, jog it in easy, or call it early. It’s not worth crashing and burning out there—been there, done that.
Pro Tip: Train with It, Don’t Race with It
Race day is not the time to try a new breakfast burrito.
Test your fueling during training. Try new foods on a 10K tempo run—not a marathon.
Keep notes—simple stuff:
- What you ate
- When you ate it
- How you felt
After a few weeks, you’ll start to see what works for you.
Your Turn:
What’s your go-to pre-run fuel?
Are you a toast-and-jam runner or team black coffee and banana?
What to Eat After Running (Fasted or Not)
No matter how you ran—fasted or full—what you do after matters just as much.
Why Refueling is a Big Deal
Right after you stop, your body is in sponge mode.
- Carbs top off your glycogen tank
- Protein starts rebuilding muscle
If you skip this window, you’re setting yourself up for:
- Soreness
- Slow recovery
- A rough next run
My Favorite Post-Run Meals
Here in Bali, I’m all about a mango-and-yogurt bowl with granola.
Sometimes it’s eggs, toast, and a slice of avocado.
Or a banana-spinach-whey smoothie if I’m short on time.
Anywhere in the world? Stick with the carb + protein formula.
Great combos:
- Peanut butter and fruit on toast
- Turkey sandwich with veggies
- Salmon and rice
- Chocolate milk (yep, it works)
👉 The goal: Refuel. Rebuild. Repeat.
Don’t Skip the Fluids
Hydration isn’t a “nice to have”—it’s a must.
Right after a run, I chug at least 8–16 oz of water.
For those hot, sweaty sessions, I’ll throw in some coconut water or add a pinch of salt or an electrolyte tab.
A sports medicine resource backs this up: the best way to avoid dehydration is drinking before, during, and after your runs.
My Post-Run Routine
Here’s what I do almost every day:
- Finish my run
- Chug water
- Sit down and foam roll or stretch
- Then refuel with a proper breakfast or lunch, depending on the time
💥 This routine has saved my legs more times than I can count.
What’s your recovery ritual?
Do you eat right away or chill first?
How to Figure Out What Works for You
No one-size-fits-all rule here. You’ve gotta test, tweak, and listen to your body.
Track and Reflect
Start simple: make a note in your phone or training app after each run.
- “Did I eat?”
- “What did I eat?”
- “How did the run feel?”
After a couple of weeks, patterns pop up.
Maybe you’re a beast on Tuesday morning fasted runs, but crash on Thursdays. That’s gold.
Drop the Dogma
Too many runners get caught up in what they “should” do.
Look, some days I love running fasted—it feels clean, sharp, focused. Other days, I’m dragging until I eat half a banana.
Don’t follow a method just because someone online swore by it.
Even research agrees: performance and safety beat theory every time.
If you crashed mid-run from going fasted? Adjust. Don’t muscle through it again out of pride.
Think in Training Blocks
Don’t judge one run. Zoom out.
Maybe fasted runs work for recovery weeks. Maybe you fuel up on speed session days.
You can alternate or mix things up depending on your plan. Be flexible.
Tie It to Your Goals
If your main goal is fat loss, fasted runs can help.
But calories still matter most at the end of the day.
If performance is your focus, then fuel like it.
A major sports nutrition review nailed it: “Performance is fuelled with carbohydrate” [medium.com].
I tell all my runners:
Use fasted running as a tool, not a rule. Don’t let it run your training plan—you’re in control.
Use Tech (or Paper)
Apps like Strava, Garmin, or even just a journal can help you track:
- Mood
- Energy
- Hunger
- Pace
You’ll start seeing patterns like:
“I’m slower on fasted tempos” or
“I run smoother after lunch.”
Self-knowledge is the real secret weapon.
Quick Question
Have you tested fasted runs yet?
What did you notice? Was it mental clarity—or a crash-and-burn?
Fueling Tips Based on Your Running Style
Look, not every runner trains the same—and not everyone fuels the same either.
Here’s how I break it down for the different types of runners I coach (and how I’ve messed up or dialed it in myself over the years):
🟢 Beginners
Just getting started?
Try a few short runs on an empty stomach and see how it feels. It’s totally fine to run fasted—as long as you’re not getting dizzy, nauseous, or dragging your feet the whole time.
Some folks do well with just a banana or a cup of coffee before an easy jog.
Me? I started with nothing but water and ended up bonking one morning on a 30-minute run. Lesson learned.
Set a routine.
Your body adapts faster when it knows what to expect.
If one day you’re feeling totally wiped, grab a small snack and try again tomorrow.
This is all trial and error—don’t stress it.
🔥 Runners Focused on Fat Loss
Fasted running can tap into fat stores during the workout—yep, that’s true.
But don’t let that trick you into thinking it’s some kind of fat-burning magic wand.
Fat loss still comes down to the old formula: burn more than you eat.
Research (like on Healthline and VeryWellFit) shows some people feel less hungry after a fasted run, but others overeat later.
I’ve seen both play out with clients—and in my own fridge raids.
So use fasted running if it fits your routine, but don’t rely on it as your main fat-loss weapon.
Your daily food choices and consistency matter way more.
🏁 Competitive Runners
If you’re chasing a PR or prepping for a race, skip the fasted stuff before any hard effort.
Trust me—I’ve had athletes blow interval sessions just because they didn’t eat.
A small meal or even half a banana before a workout can make the difference between hitting splits or slogging through a mess.
We’ll sometimes do low-carb sessions early in base training to teach the body to burn fat more efficiently.
But as race day gets closer, carbs become non-negotiable. They’re your fuel.
If you’re doing speedwork, tempo runs, or anything race-specific—fuel up.
⏰ Intermittent Fasters or “Minimalist” Eaters
Doing 16:8 or OMAD? No worries—you just need to time your runs right.
If your eating window is 12–8 p.m., a morning run will be fasted.
An afternoon run will be fueled.
Either way, plan ahead.
Hydrate well, and always carry a gel or something quick just in case you bonk.
When I played around with fasting, I had one golden rule:
Don’t schedule hard workouts when you’re running on fumes.
Hit your long or intense runs close to mealtime so you’ve got fuel in the tank.
Fasted vs. Fed – Quick Comparison
Here’s the cheat sheet I give my clients when they ask, “Should I run fasted or fueled?”
Category | Fasted Running | Fueled Running |
---|---|---|
Best for | Easy, short runs (especially in the morning) | Long runs, workouts, race pace efforts |
Performance | Lower past 45–60 mins | Higher (better strength, pace, and focus) |
Fat burning | Higher during the run (ntu.ac.uk, healthline.com) | More calories burned total, especially at high intensity |
Risk of fatigue | Moderate to high | Low |
Injury risk | Higher (fatigue messes with form) | Lower (more stable form and awareness) |
Convenience | Very high | Moderate (need to time food) |
Who should avoid | People with diabetes, adrenal issues (healthline.com) | Basically no one—almost everyone can fuel safely |
My Take?
You don’t win medals for skipping breakfast.
Know when to run light and when to bring the fuel.
Test it. Learn what you need.
Fasted Running Q&A
Q: Can I drink coffee before a fasted run?
Yes, and I usually do.
Black coffee has zero real calories and gives a nice boost.
According to Mayo Clinic, it’s fine pre-run.
But heads-up: some runners (me included) have had days where coffee hits wrong and wrecks the gut.
If that’s you, go with water or try half a cup.
Q: Is it bad to always run fasted?
Not bad—but not great either. Mix it up.
I’ve gone through streaks of daily fasted runs and eventually noticed I felt slower, more tired, and less motivated.
Now, I save my fasted runs for easy days and fuel up on workout days.
That balance keeps me stronger and avoids burnout.
Q: What’s a good snack if I only have 10 minutes?
Easy—banana, honey spoon, dates, fig bar.
You just need a quick hit of sugar—something that digests fast.
One of my go-tos is a spoon of honey chased with water.
You’ll feel it kick in right as your legs start to wake up.
Q: Is fasted running better for fat loss?
It might burn more fat during the run, but that doesn’t always translate to more fat loss overall.
Studies show that total calorie intake still decides the outcome.
In other words—fasted running won’t save a bad diet.
Use it as one tool in the box, not the whole toolbox.
Final Thoughts — It’s Just a Tool
Fasted running isn’t some magical solution. It’s a tool—use it when it makes sense.
I use it mostly on easy mornings when I’m short on time.
But when I’m prepping for a race or doing anything tough, I eat first.
That’s the rule I live by:
Test during training, never gamble on race day.
So don’t force yourself into trends.
Listen to how your body responds.
If you’re dragging all day after a fasted run, maybe that’s not your move.
If it fits your rhythm and helps you stay consistent, great.
Just don’t skip the basics: fuel, rest, consistency.
Your Turn:
What’s your go-to pre-run plan?
Empty stomach and black coffee? Or do you need a bite before you lace up?
Drop your thoughts below—let’s swap notes.