Day 73 of 100 Days Muscle Resistance Workout Challenge
Focus Topics: Men vs. women’s metabolism and exercise. How men and women differ in fuel utilization, men burn more carbohydrates, while women rely more on fat oxidation during moderate exercise.
Learning Material: Men vs women metabolism exercise
When we talk about “metabolism,” most people imagine a single on/off switch. In reality, your metabolism is more like a smart hybrid engine that chooses which fuel to burn depending on your hormones, workout intensity, and even stress levels.
And here’s the fascinating part:
Men and women run this metabolic “engine” differently.
Scientists noticed this years ago, but modern sports physiology confirms the pattern:
- Men tend to burn more carbohydrates during exercise.
- Women burn more fat, especially during moderate-intensity workouts.1
Let’s break this down in a simple, intuitive way.
1. Carbs vs. Fat: Why the Difference Exists
The difference begins with hormones, especially estrogen.
Women (higher estrogen):
- Rely more on fat oxidation (burning fat as fuel).
- Conserve glycogen (stored carbohydrate in muscles).
- Maintain energy more steadily during longer workouts.
Men (higher testosterone):
- Burn carbs more quickly.
- Have higher glycolytic activity (turning carbs into rapid energy).
- Experience sharper rises and falls in energy depending on glycogen.
Why does this matter?
Because the fuel your body prefers affects how you train, how you recover, and how you maintain muscle mass.
2. What This Means for Your Workouts
Women tend to be more “fat-efficient” at moderate intensities.
This means fasted-state moderate exercise doesn’t immediately eat into muscle, as long as protein intake is solid during the day.
But there’s a catch:
Women may experience nausea or dizziness when exercising on an empty stomach.
This is not weakness; it’s biology. Women have different glucose regulation patterns and may have stronger adrenaline responses in the morning.
Think of it like this:
Men run like gasoline cars: fast-burning, carb-powered.
Women run like hybrid cars: steady, efficient, and naturally conserving fuel.
Neither is better. They’re built for different profiles of endurance, strength, and recovery.
Real-World Example
Imagine two runners going for a 45-minute jog:
- Male runner:
Burns through glycogen quickly → gets tired faster → needs carbs sooner → recovers quicker with enough carbs. - Female runner:
Burns more fat → has stable energy throughout → but may feel nauseated if she hasn’t eaten anything → needs balanced meals after to prevent muscle loss.
This explains why many women say:
“I feel terrible working out on an empty stomach,”
even though their bodies technically can burn fat efficiently.
Your hormonal environment controls energy stability, not just your willpower.
My Reflection
I’ve experienced nausea during workouts in the past, and it makes perfect sense now. Back then, I exercised right after work. Because I was “dieting,” I often didn’t eat enough during the day. By 5:30 p.m., I was starving. Working out with almost no fuel naturally led to nausea, because my body simply didn’t have enough glycogen available to support the exercise.
Understanding how the body actually works is essential for building muscle. I still remember the boy my age in my homestay family who gained noticeable muscle in just a month. Meanwhile, I struggled. I used to envy how easily men seem to develop muscle, but now I know it doesn’t mean women are inferior. Our physiology is different, and in some ways, we’re actually better at maintaining muscle long term. We simply need more patience with the process.
Here’s what I finally understand:
Women burn more intramuscular fat during exercise. Afterward, the body replenishes that fat by pulling from subcutaneous stores. And the day-to-day “muscle mass” fluctuations I see on the scale are mostly from water changes, glycogen shifts, and tissue repair, not actual muscle disappearing.
Now that I truly grasp the physiological differences between men and women, the next step is to study more and design a training system that works for my body, not against it.
As for the abdominal pain I felt, it may have come from bracing my core too hard, since I was intentionally visualizing my abs becoming solid during the workout. It’s possible I simply activated the muscles more intensely than usual.
Biometric data
Change in Weight from Day 1: -5.6 lb.
Skeletal Muscle: 39.7%
Muscle Mass: 94.0 lb.
Adjustment Ideas (Strategic Adjustments)
Here are a few small, realistic, science-backed adjustments you could choose from:
1. Pre-Workout Fuel Micro-Adjustment
Add one simple pre-exercise snack on mornings when you feel faint or nauseated.
Keep it small: one egg, a bite of banana, or a few nuts.
2. Shift One Workout to the Afternoon (If Possible)
Women often perform better later in the day when glucose availability and cortisol rhythms are more favorable.
3. Balance Protein Throughout the Day
Instead of relying heavily on eggs in the morning, consider adding a small protein serving at lunch (chicken, tofu, cottage cheese, Greek yogurt).
Your muscle mass reacts immediately to consistent protein intake.
Note
- Tarnopolsky, M. A. (2008). “Sex differences in exercise metabolism and the role of 17-β estradiol.” Applied Physiology, Nutrition, and Metabolism, 33(1), 65–74.
https://doi.org/10.1139/H07-109 ↩︎