I Tried Intermittent Fasting While Working Out — My Energy Levels Were Unexpected

Last updated on: November 19, 2025

If you’re anything like me, you’re always looking for something that will make you feel better, lighter, more balanced, or just more you. I had heard so much about intermittent fasting — the energy boosts, the mental clarity, the weight control — and I wondered if it would work for me too. But I didn’t just want to fast. I wanted to combine it with my normal workouts and see what really happened to my energy levels.

Spoiler: It wasn’t what I expected at all.

In fact, parts of the experience shocked me — in both good and not-so-good ways.

So here’s my honest journey of what it felt like to try intermittent fasting while still lifting weights, doing cardio, and keeping up with everyday life.

Table of Contents

Why I Even Tried It

I’m not the kind of person who jumps on every wellness trend. But I kept seeing women say intermittent fasting boosted their energy and helped them focus throughout the day. I was curious.

My biggest struggle before fasting was energy swings — feeling amazing in the morning and absolutely crashing in the afternoon. I wanted more steady, predictable energy, not the roller coaster I was used to.

So I told myself:
One month. Fasting + workouts. No excuses.
Let’s see what happens.

What I Chose: The Simple 16:8 Method

There are lots of ways to do intermittent fasting, but I chose the 16:8 method because it sounded doable. I would fast for 16 hours and eat during an 8-hour window. For me, that meant:

No breakfast
First meal around 12:00 p.m.
Last meal around 8:00 p.m.

I still kept my regular workout routine:

Strength training 3–4 days a week
Light cardio or walking on the other days

And yes, I worked out fasted in the morning, which was the part I was the most nervous about.

Week 1: I Questioned Every Life Decision

Let me be honest — the first week was rough. If anyone tells you fasting feels magical on Day 1, I just don’t believe them.

Here’s what I felt:

I woke up hungry.
I felt a little dizzy during the first few workouts.
Coffee became my best friend.
By 11 a.m., I was counting down minutes until noon.

The workouts were the hardest. I didn’t feel weak, exactly, but I didn’t feel strong either. I felt like my body was still learning what was going on.

My mood was also… interesting. I wasn’t angry, but I was definitely not my most patient self.

The good thing? I slept so well. My stomach felt light. And I noticed I wasn’t bloated — at all.

So, even with the rough patches, I kept going.

Week 2: Something Shifted

By the second week, my body started to get the memo.

My morning workouts suddenly felt smoother. I wasn’t starving when I woke up. I could actually focus until noon without thinking about food nonstop.

And the biggest surprise?
My energy in the afternoon was better than it had been in months.

Instead of the usual 3 p.m. crash, I felt steady and sharp. I was drinking less coffee and still feeling awake. The mental clarity people talk about? I finally understood.

It wasn’t perfect — I still had moments where I wished I could have breakfast — but I was seeing enough progress to stay motivated.

Week 3: The Unexpected Energy Boost

Week 3 was where things really changed for me.

I felt lighter in the mornings, my stomach felt flatter, and I was waking up with more energy than usual. My workouts were surprisingly strong. Not “run a marathon” strong, but more “I can actually lift heavier” strong.

It almost felt like my body had unlocked something new. I didn’t expect that — especially not while training on an empty stomach.

I also started noticing:

Less sugar cravings
Better digestion
Better mood
Less bloating
More control over emotional eating

This was the point when I thought:
Okay… maybe there’s something to this.

Week 4: The Honest Challenges

Even though I felt better overall, week four came with some honest struggles.

Socially, fasting can be weird. If you’re out with friends and someone orders brunch at 10 a.m., you’re just sitting there sipping iced water, being all mysterious.

Hormones also came into the picture. Right before my period, I felt hungrier and more tired during workouts. Some days, fasting felt natural. Other days, I felt like my body wanted breakfast and a hug.

So yes — fasting isn’t perfect, and it doesn’t magically work the same every day.

The Biggest Surprise: My Energy Didn’t Drop — It Stabilized

Here’s the part I didn’t see coming:

My energy levels didn’t drop. They actually became more stable.

Before fasting, I thought I needed morning food to function. But fasting taught me something completely different — my body had energy stored, I just wasn’t used to accessing it.

I felt:

More clear-headed
Less sleepy during the day
More focused at work
More in tune with my hunger cues

It wasn’t a burst of energy. It was steady, calm, predictable energy. And honestly, I preferred that.

Would I Recommend Intermittent Fasting While Working Out?

Here’s my honest take:

Yes — but only if you listen to your body.

Fasting can feel amazing for some women, but difficult for others. If you’re already stressed, not sleeping well, or dealing with hormonal issues, fasting may feel too hard.

But if you want a simple routine and more steady energy, you might be surprised by how well your body adapts — just like mine did.

Tips If You Want to Try It Too

These helped me the most:

Start with 14:10 instead of 16:8.
Drink lots of water — like, way more than you think.
Add electrolytes or a pinch of salt in water if you feel light-headed.
Keep workouts lighter in the beginning.
Don’t ignore your hormones — eat if you need to.
Break your fast with protein, not sugar.

And most importantly:
Don’t force it.
Your body is smarter than any trend.

My Final Verdict

Intermittent fasting while working out wasn’t what I expected. I thought I would feel tired, cranky, and weak. But instead, I felt clearer, lighter, and — surprisingly — more energized.

Will I continue? Yes, but not every single day. I’ll listen to my body and give it what it needs.

If you try it too, I hope you discover the version of you that feels balanced, strong, and energized — because your body deserves that.