As a personal trainer, one of the most common questions I hear is, “Should I be doing fasted cardio for fat loss?”
Fasted cardio, or performing cardiovascular exercise on an empty stomach (usually after an overnight fast), has gained popularity in recent years as a potential way to burn more fat. But;
Does science support this claim?
Does fasted cardio affect men and women differently?
Let’s break it down with evidence-based insights to help you make informed decisions about your workout routine.
What is Fasted Cardio?
Fasted cardio typically refers to exercising after several hours without food, most often first thing in the morning after an overnight fast. The theory is that, because your glycogen (stored carbohydrate) levels are lower, your body will burn more fat as fuel. This idea has been around for years, but what do studies actually show?
What Does Science Say?
1. Fat Oxidation During Fasted Cardio
Several studies have confirmed that fasted cardio does increase fat burning during exercise compared to fed cardio. One study published in the Journal of Applied Physiology found that individuals who performed cardio in a fasted state burned more fat during their workout than those who had eaten prior, there’s a key point to remember: while more fat may be burned during the exercise session, this doesn’t necessarily translate to more overall fat loss over time. Total fat loss depends on your calorie balance across the day and week, not just during the workout.
2. Does Fasted Cardio Lead to More Fat Loss?
While fasted cardio can increase fat burning, the total amount of fat lost over time remains similar whether cardio is performed in a fasted or fed state. A study published in the British Journal of Nutrition followed participants who performed cardio either in a fasted state or after eating. After four weeks, both groups experienced the same amount of fat loss. However, whilst fasted cardio might burn more fat during the workout, the overall impact on body fat reduction is similar when total calorie intake and expenditure are controlled.
Is Fasted Cardio Effective?
While fasted cardio may have its place in some people’s fitness routines, it’s important to weigh its pros and cons.
Benefits of Fasted Cardio:
- May improve fat oxidation (fat burning) during exercise.
- Convenient for morning workouts when eating a meal might feel uncomfortable.
- Some people enjoy the mental clarity and energy they feel working out fasted.
Drawbacks of Fasted Cardio:
- May not lead to more fat loss compared to fed cardio when overall calories are controlled.
- Can increase cortisol levels, which may hinder muscle retention or fat loss, especially in women.
- Exercising on an empty stomach may lead to reduced performance or fatigue, especially in high-intensity workouts.
Who Should Consider Fasted Cardio?
Fasted cardio can be beneficial for individuals who:
- Prefer to work out in the morning without eating.
- Focus on low to moderate-intensity cardio (such as walking or light jogging).
- Have stable energy levels during fasted training.
However, if your goal is to maximise performance in strength training or high-intensity workouts, fasted cardio might not be the best option. It’s essential to listen to your body. If you feel weak or fatigued during fasted cardio, it’s better to fuel up before your session.
Final Thoughts – Does Fasted Cardio Make a Difference?
Fasted cardio can increase fat burning during the workout, but its long-term impact on fat loss is comparable to fed cardio when overall calories are equal. Whether you choose to do fasted cardio depends on your personal preferences and how your body responds.
Ultimately, the best approach to fat loss and fitness is the one that fits your lifestyle, feels sustainable, and supports your long-term goals. Whether you prefer fasted or fed workouts, consistency, proper nutrition, and recovery will always be the keys to success.