How to Lose Weight By Fasting and Doing Cardio

August 22, 2025

Combining fasting and cardio can be a powerful strategy for accelerating weight loss and efficiently burning fat. When you engage in fasted cardio sessions, especially in the early morning, after an overnight fast, your body taps into fat stores for fuel due to lower insulin levels and depleted glycogen stores.

This boosts fat oxidation, making your cardio workouts more effective for long-term body composition changes. Whether you’re practicing intermittent fasting or full-day fasting, pairing it with the best aerobic exercises for fat loss, like brisk walking, cycling, or HIIT, helps maximize your calorie deficit and burn more fat over time.

But success depends on more than just willpower. To truly benefit from the fat-burning effects of fasted exercise, your strategy must be tailored to your lifestyle and fitness level. Designing a sustainable plan that includes consistent aerobic exercise, proper post-exercise meals, and a balanced diet is key to maintaining your results.

That’s where Crunch Fitness comes in. With flexible hours, a mix of aerobic exercise workouts, and certified personal trainers, Crunch creates the perfect environment for anyone looking to improve their body fat percentage and reach their goals.

The Science Behind Fasting and Cardio for Weight Loss

Doing cardio workouts while fasting is a smart way to help your body burn more fat and support healthy weight loss. When you work out without eating first—also known as fasted cardio—your body must use stored fat as fuel. This creates a powerful fat-burning effect that can lead to long-term changes in body composition and a reduction in body fat percentage.

Body Composition: How Intermittent Fasting Affects Fat Burning

When you practice intermittent fasting, your body goes several hours without food, usually 12 to 16 hours. During this time, your insulin levels drop, and your glycogen stores (your body’s stored energy) begin to run low. That’s when your body begins to use its fat stores for energy. Engaging in aerobic exercise in a fasted state can increase fat oxidation by up to 30%. That means you burn more fat than you would during a workout after eating.

Benefits of Fasted Cardio

The combination of fasted cardio and intermittent fasting doesn’t just help during your workout; it also keeps burning fat afterward. It also improves how your body uses insulin and teaches it to switch more easily between burning food and burning fat.

Over time, this can help you lower your body fat percentage, maintain a healthy body weight, and support your overall fitness goals.

At Crunch Fitness, we make it easier. With flexible hours, expert trainers, and different aerobic exercise equipment, you can design a plan that fits your life and helps you stay consistent.

Popular Intermittent Fasting Methods

Intermittent fasting provides a flexible approach to support your cardio-based weight loss goals, particularly when combined with regular aerobic exercise. The key is to find a fasting style that fits your lifestyle, schedule, and cardio workout preferences.

At Crunch Fitness, our certified personal trainers can help you create a realistic plan that aligns your cardio sessions with your eating strategy, allowing you to burn fat effectively.

16:8 Method (Time-Restricted Eating)

The 16:8 method is the most popular and beginner-approved intermittent fasting strategy. It involves eating all your meals within an 8-hour window and fasting for the remaining 16 hours.

Research shows that time-restricted eating like this can improve body composition, reduce body weight, and support metabolic health. This approach is perfect if you like to work out in the morning or evening, as it’s easy to time your cardio workouts either before or after your eating window.

14:10 Method (Beginner-Friendly)

If you’re new to fasting, the 14:10 method is a gentle introduction. You fast for 14 hours and eat during a 10-hour window. This schedule gives your body time to adjust to fasting while still promoting fat oxidation and supporting weight loss. It also offers more flexibility for fitting in aerobic exercises around your daily routine, great for busy professionals or parents on the go.

18:6 Method (Advanced Approach)

The 18:6 method is designed for more experienced fasters and involves an 18-hour fasting period followed by a 6-hour eating window. While this method can intensify fat-burning and improve insulin sensitivity, timing your fasted cardio becomes more critical. Advanced practitioners often use this strategy to break through plateaus and accelerate body fat reduction.

Best Cardio Workouts to Combine with Fasting

When it comes to fasted cardio, the best exercises are ones that are safe, sustainable, and help your body tap into its fat stores for energy. Whether you’re an early bird hitting the gym after an overnight fast or squeezing in a morning workout before breakfast, choosing the right cardio workouts is key to seeing results without burning out.

Low-Intensity Steady-State (LISS) Cardio

Think of LISS cardio as a power walk through the park with your favorite playlist or a slow ride on a stationary bike while watching a show. It keeps your heart rate around 60–70% of its max, the sweet spot for fat oxidation.

At Crunch, you can hop on a treadmill, elliptical, or recumbent bike and enjoy a distraction-free, controlled setting to make those longer fasted cardio sessions fly by.

Moderate-Intensity Interval Training

Not ready for high-intensity sprints? No problem. Try alternating between a steady jog and a brisk walk. This moderate-intensity interval format burns more calories than LISS but doesn’t overwhelm your system—perfect during a fasted state. Many Crunch locations offer group fitness classes like cycling or circuit training that can be customized to match your energy levels when fasting.

Walking and Incline Training

Walking may seem simple, but adding a slight incline turns it into a fat-burning powerhouse. Imagine hiking up a hill on a beautiful trail—that’s exactly what incline walking does, but on a treadmill. It increases calorie burn while staying gentle on your joints. It’s ideal for beginners and experienced gym-goers alike, especially during intermittent fasting.

Cardio Workouts at Crunch Fitness

1. Dance & Rhythmic Cardio

Dance to HIIT: The ultimate fusion of high-intensity interval training and hip-hop-inspired dance moves. Torch fat, tone up, and groove hard.
Retro Robics: Classic aerobics meets 80s jams. It is a fun, nostalgic workout that delivers big on sweat and even bigger on smiles.
SO YOU THINK YOU CAN’T DANCE: Zero judgment, all fun. It is designed for beginners or anyone who thinks they can’t dance.
The Ultimate Dance Party: Exactly what it sounds like. A nonstop, total-body dance fest set to high-energy beats that’ll leave you smiling and sore.
Badass Ballerina: This ballet-inspired workout combines classical dance moves with strength and core training. Expect pliés with power, perfect for building balance, tone, and lower-body strength no tutu needed.

2. HIIT & Bootcamp Style

Tabata HIIT: Short bursts of max effort followed by brief recovery, perfect for fat burn.
Fat-Burning Pilates: A twist on traditional Pilates with added cardio intervals.
Tread Bootcamp:Treadmill intervals + strength moves = max fat burn in just 30 minutes. High-energy, HIIT-style cardio.
Barre Bootcamp: Ballet-inspired toning meets strength training. Sculpt your arms, core, thighs, and glutes—no dance skills required.
Belly, Butt & Thighs Bootcamp: Targeted lower-body workout with cardio bursts. Tighten your core, tone your legs, and shape your glutes.
Badass Bootcamp: One-minute drills with TRX, heavy bags, and turf work. Strength, speed, and serious intensity.
BOSU Bootcamp: Balance + strength + cardio using the BOSU. Full-body, core-focused training for all fitness levels.
StrongHIIT: A strength class that pushes your limits. You’ll rotate through three rounds of pulling, pushing, and lifting, with the option to add weight or intensity each time.

3. Cycling & Ride-Based

The Ride: Let the Beat Drop is a 45-minute indoor cycling class at Crunch that combines HIIT, rhythm-driven intervals, and high-energy music for a fun, low-impact cardio burn.
Heavy Mileage: This class is a more extended, stamina-focused ride that mimics long-distance biking. It is ideal for those looking to build stamina and experience the challenge of sustained effort.
HIIT the Road: A HIIT class that alternates between intense bursts of speed and resistance with recovery periods. This format is designed to maximize calorie burn and improve cardiovascular fitness quickly.
The Ride: Level It Up is an energizing 45-minute indoor cycling workout focused on boosting power, speed, and stamina with guided, music-driven intervals.

4. Conditioning & Endurance

Cardio Tai Box: A martial arts-inspired cardio workout using punches, kicks, and combos.
Push The Perimeter: This class moves in lines utilizing barbells, dumbbells, slam balls, and kettlebells.

5. Low-Impact Options to Reduce Body Fat

Cardio Sculpt: A gentler blend of cardio and toning for those easing into fitness.

You can read our article: 7 Low-Impact Exercises for Weight Loss for All Fitness Levels

Timing Your Fasting and Cardio Schedule

To get the most out of combining fasting and cardio, timing matters. The right schedule boosts fat burning, supports recovery, and helps avoid issues like fatigue or muscle loss. The best approach depends on your lifestyle, goals, and how your body responds.

Morning fasted cardio is one of the most effective strategies for weight loss. Working out after an overnight fast means your glycogen stores are at their lowest and your fat-burning hormones, like cortisol, are naturally higher. It’s a great way to kickstart your day, torch calories, and get your workout done before life gets busy.

Some prefer evening cardio during longer fasting windows—especially those practicing intermittent fasting who eat lunch as their first meal. This works well if you feel stronger or more focused later in the day, and it still keeps you in a fat-burning state.

Another option is to work out 1–2 hours before your first meal of the day. This timing supports the use of fat during exercise and allows for efficient muscle recovery when you eat. It’s a smart way to transition from fat oxidation to refueling with purpose.

No matter your schedule, Crunch Fitness offers flexible hours and expert guidance to help you find your perfect fasting and cardio rhythm.

Tips for Achieving Your Weight Loss Goals via Fasting and Cardio

Combining fasting and cardio is a decisive method for burning fat and transforming your body composition, but it’s not something you should jump into without a plan.

1. Start Gradually

If you’re new to fasted exercise, start with shorter fasting windows, such as the 14:10 method, and pair it with low-intensity steady-state (LISS) cardio. Once your body adapts, you can gradually increase both the fasting duration and the intensity of your cardio workouts. Building up slowly helps prevent burnout, fatigue, and potential muscle loss.

2. Focus on Hydration and Electrolytes

During fasting, your body sheds more water and sodium, which increases the risk of dehydration, especially when you’re sweating through fasted cardio sessions. To stay safe:

Drink water consistently throughout the day, especially before and after workouts.
Add electrolyte tablets or a pinch of sea salt to water if you’re training fasted for extended periods.
Avoid sugary sports drinks unless needed for high-intensity sessions.

Proper hydration helps prevent symptoms of low blood sugar, such as dizziness or cramps, and supports consistent energy levels during training.

3. Listen to Your Body

Fasted cardio isn’t for everyone. Warning signs, such as nausea, dizziness, shakiness, or excessive fatigue, mean it’s time to stop and reassess. Some people, especially those with medical conditions or on certain medications, should consult their healthcare provider before starting a fasting and cardio program.

Empty Stomach? Proper Nutrition

What you eat and when you eat it, can make or break your results. Combining intermittent fasting with aerobic exercise requires a strategic approach to nutrition that fuels performance, supports fat oxidation, and promotes recovery.

Crunch’s trainers can help you create a personalized nutrition plan that aligns with your fasting schedule, ensuring you stay energized and strong for every session.

Strategic meal timing around workouts helps your body transition from fat burning during cardio to muscle repair and energy replenishment afterward.

Breaking Your Fast Post-Workout

After a fasted workout, it’s crucial to eat soon, ideally within 30 to 60 minutes, to kickstart recovery. A meal rich in protein supports muscle repair and helps preserve lean mass, especially when you’re training consistently in a fasted state.

Adding complex carbohydrates (like oats, sweet potatoes, or quinoa) helps replenish glycogen stores without derailing your caloric intake.

If your eating window is short, focus on hitting your protein goals with every meal. Try smoothies with protein powder, Greek yogurt with fruit, or grilled chicken with veggies and rice.

Tracking Your Progress

When you’re pairing fasting with cardio, the number on the scale doesn’t always tell the full story. Your energy levels, workout performance, and recovery speed often improve before you see noticeable weight loss.

That’s why it’s important to track multiple metrics:

How energized do you feel during fasted workouts?
Are your cardio sessions getting easier or longer?
Do you recover faster between workouts?

These signs mean your body is adapting—and it’s working.

Body composition analysis is a more effective way to measure progress than relying on weight alone. It shows changes in muscle mass, body fat percentage, and overall body mass, critical markers when doing fasted cardio.

Crunch Fitness offers body composition tracking tools that give deeper insights into how your routine is shaping your body.

Consistency is the secret ingredient in any successful fitness journey, and with Crunch’s support, you’ll have the tools and guidance to keep going strong.

Start Your Fasting and Cardio Journey with Crunch

Crunch promotes a culture of positivity, inclusivity, and fun with no judgments by providing an environment for all individuals regardless of their health and fitness goals. Find a Crunch gym near you to try our free trial membership, or join Crunch now. We’re here for you – at the gym or at home. Access the best live & on-demand workouts anytime, anywhere with Crunch+. Ready to get sweaty? Try hundreds of workouts for free! Start your free trial now!

FAQ’s

Is it Safe to Do Cardio While Fasting?

Cardio while fasting can be safe for most healthy people, especially when performed at low to moderate intensity. It can even enhance fat burning and support weight loss goals.