You’ve probably heard it before: ‘Workout fasted and you’ll burn more fat.’

It sounds simple. Logical, even. But as a university nutrition lecturer and sports nutritionist who’s helped over 500 clients, I can tell you – this is one of those half-truths that thrives on TikTok, not in science.

So, does fasted training actually help you burn more fat?

Short answer: Not exactly. Let me break it down.

What Is Fasted Training?

Fasted training means exercising without eating beforehand, typically after an overnight fast. The theory is that your body, lacking quick energy from food, will tap directly into fat stores for fuel.

Sounds great, right? But your body has other plans.

Myth: No Food = More Fat Burn

While the idea isn’t entirely wrong, it’s far from the whole story. Here’s what really happens:

• Your body burns glycogen first. Glycogen (stored carbs) is your go-to fuel, especially in the first 60-90 minutes of exercise.
• Fat primarily becomes fuel after glycogen is depleted. But that doesn’t necessarily mean you’re losing body fat. It’s just fuel rotation.
• Calories burned vs. calories stored still matter. Burning fat during a workout isn’t the same as burning body fat over time.

Does Exercise Intensity Affect Fat Burn?

Absolutely.

• High-intensity training (HIIT, sprints) relies heavily on glycogen.
• Lower-intensity workouts (walking, yoga) tap into fat stores more easily.

So yes, you can burn a greater proportion of fat doing low-intensity fasted workouts. But total calorie burn (and long-term body fat loss) still favors fueled training.

Women: Here’s Why Fasted HIIT May Backfire

Here’s what doesn’t get talked about enough:

• Fasted, high-intensity workouts may spike cortisol (your stress hormone).
• Women are more sensitive to hormonal stress during fasting + intense exercise.

Translation? That early-morning HIIT class on an empty stomach may be doing more harm than good. As someone who’s worked with hundreds of female clients, I recommend:

• Stick to low-intensity movement (walking, pilates, mobility) if training fasted
• Fuel up with a small carb-based snack if doing anything intense

Why Pre-Workout Nutrition Often Leads to Better Results

This isn’t about ‘ruining the fat burn.’

It’s about performance, recovery, and metabolism:

• Carbs before training = more energy = better workout = higher total calorie burn
• Better workouts build more lean muscle (and muscle = long-term fat burn)
• Improved focus and reduced injury risk when your body isn’t running on fumes

Need a quick pre-workout idea? A banana, slice of toast with honey, or a few rice cakes with nut butter will do.

TL;DR: Is Fasted Cardio a Fat-Burning Miracle?

Nope. It’s a tool, not a magic solution.

You might burn a little more fat during the session, but that doesn’t mean you’ll lose more body fat overall.

If you want results, here’s what matters most:

• Exercise consistently
• Total energy intake over the days/weeks/months
• Eat for performance, not deprivation
• Work with a qualified nutritionist (not a TikTok trend)

My Final Word (and What TikTok Gets Wrong)

As someone who teaches nutrition at the university level and speaks professionally about this topic, let me leave you with this:

Fat loss isn’t about timing your workouts perfectly. It’s about fueling your body smartly, , moving regularly, and eating the right amounts.

If you’re confused about all the conflicting advice out there, you’re not alone. My job is helping you make sense of nutrition.

Want me to speak at your next event or guest on your podcast? I specialise in cutting through misinformation and helping audiences understand the science of nutrition in a way that’s simple, evidence-based, and empowering.

Contact me here to book a speaking engagement.