Exercise for Weight Loss: Cardio vs. Strength Training

Want to lose weight? You’ve probably heard conflicting advice: cardio burns more calories, but strength training changes your body shape. So which one should you do? The truth isn’t as simple as picking sides. Both work - but in different ways. And the best results come from using them together.

Cardio Burns Calories Fast - But Only While You’re Doing It

Cardio - running, cycling, swimming, brisk walking - is the go-to for people who want to see the scale drop quickly. And for good reason. In 30 minutes, a 155-pound person can burn 300-400 calories jogging, or up to 600 cycling hard. That’s a lot of energy spent in half an hour.

That immediate calorie burn is why cardio feels so effective at first. You step off the treadmill, look at the screen, and see you’ve burned half a meal’s worth of calories. It’s motivating. But here’s the catch: once you stop moving, your metabolism snaps back to normal. The calories stop burning.

And after 8-12 weeks, most people hit a plateau. Your body gets efficient. You burn fewer calories doing the same workout. You have to run longer, faster, or farther to keep losing weight. That’s why so many people quit cardio after a few months - the results stall.

Strength Training Burns Fewer Calories - But Keeps Burning After You Stop

If you’ve ever tried strength training for weight loss, you might’ve been frustrated. Thirty minutes of lifting weights? You only burn 90-150 calories. That’s less than a 10-minute jog. So why bother?

Because strength training doesn’t just burn calories during the workout - it keeps burning them for up to 48 hours after. This is called EPOC: excess post-exercise oxygen consumption. Your body works hard to repair muscle tissue, restore energy stores, and cool down. That takes fuel.

More importantly, muscle burns more calories at rest than fat. Every kilogram of muscle uses 13-15 calories a day just to stay alive. Fat? Only 4.5-5. So if you gain 2kg of muscle and lose 2kg of fat, your body burns an extra 16-20 calories every single day. That’s about 1.5kg of fat lost per year - just from being more muscular, no extra workouts needed.

Body Composition Matters More Than the Scale

This is where most people get tripped up. The scale doesn’t tell the whole story.

One study tracked 6-month weight loss results across three groups: cardio-only, strength-only, and a mix of both. The cardio group lost 9.7% body fat - but also lost 0.3kg of muscle. The strength group lost 7.1% fat - but gained 2.3kg of muscle. The combo group? They lost 12.4% fat and gained 1.8kg muscle. That’s the sweet spot.

Think about it: two people lose 5kg. One loses muscle and fat - they look thin but soft. The other loses fat and gains muscle - they look lean, toned, and tighter. Clothes fit better. Posture improves. You feel stronger. That’s body recomposition - and it’s what real, lasting weight loss looks like.

Women’s Health Magazine analyzed data from the National Weight Control Registry - people who lost 30kg or more and kept it off for over 5 years. The most successful ones didn’t just do cardio. They did strength training 3+ times a week. They knew the scale wasn’t the goal. Their goal was to keep the weight off - and muscle helped them do that.

Someone lifting weights with glowing energy waves showing post-workout calorie burn.

HIIT: The Middle Ground

If you’re short on time but want the benefits of both, high-intensity interval training (HIIT) is your best bet. A 20-minute HIIT session - think 30 seconds sprint, 60 seconds walk, repeat - can burn 25-30% more calories than steady-state cardio. It also spikes EPOC 12-15% higher than regular cardio.

Studies show HIIT improves insulin sensitivity, reduces belly fat, and boosts metabolism without needing hours on the treadmill. It’s brutal, but efficient. And you don’t need equipment - bodyweight sprints, jump squats, burpees, and mountain climbers work just fine.

What Experts Actually Recommend

The American College of Sports Medicine (ACSM) doesn’t pick sides. Their 2023 guidelines are clear: for weight loss, do 150 minutes of cardio and 120 minutes of strength training each week. That’s about 30 minutes of cardio five days a week, and two full-body strength sessions.

Dr. Timothy Church, a leading obesity researcher, says a 2:1 cardio-to-strength ratio works best for 78% of people. Dr. Kelly St. George, an exercise physiologist, found that combining both leads to 37% more fat loss than either alone. Even Dr. James Levine, who argues that everyday movement matters more than workouts, admits that structured exercise still plays a key role.

It’s not about choosing one. It’s about layering them.

Why People Fail - And How to Avoid It

Most people don’t fail because they’re lazy. They fail because they do the wrong thing.

Cardio-only folks plateau because they keep doing the same routine. Strength-only folks get discouraged because the scale doesn’t move - or even goes up. That’s normal. When you start lifting, your muscles hold more water. You might gain 1-2kg in the first few weeks. That’s not fat. That’s your body adapting.

The biggest mistake? Not eating enough protein. To build muscle, you need 1.6-2.2 grams of protein per kilogram of body weight. Only 32% of people trying to lose weight hit that mark. Without protein, your body breaks down muscle for energy - even if you’re lifting weights.

Another issue: not progressing. If you’re doing the same weights every week, you’re not getting stronger. And if you’re not getting stronger, you’re not building muscle. Increase the weight by 2.5-5% every week. That’s all it takes.

Split image of scale disappointment vs. confident body transformation in jeans.

What Works Best in Real Life

Look at real people, not just studies. On Reddit’s r/Fitness, a top thread with over 3,400 upvotes asked: “6 months of cardio vs weights for fat loss.”

68% of people who did both lost more than 15% body fat. Only 42% of cardio-only and 31% of weights-only did.

Cardio users loved the immediate energy boost and stress relief. Strength users loved how their clothes fit better - even when the scale didn’t budge. One person wrote: “I lost 8kg but gained muscle. My jeans went from size 12 to 8. The scale said I gained 1kg. I didn’t care. I looked better.”

And here’s the kicker: people who tracked both cardio and strength training kept 72% of their weight loss after 18 months. Those who did only one? Only 48% kept it off.

Where to Start - Simple Plan for Beginners

You don’t need a gym membership or fancy gear. Here’s what works:

Do 3 days of cardio: brisk walking, cycling, or dancing. 30 minutes each time. Keep it at a pace where you can talk but not sing.
Do 2 days of strength: bodyweight squats, push-ups (on knees if needed), lunges, planks. Add dumbbells or resistance bands when you can.
Eat protein at every meal: eggs, chicken, tofu, Greek yogurt, lentils. Aim for 20-30g per meal.
Progress slowly: add 1-2 reps or 1kg more weight every week.
Rest: sleep 7-8 hours. Recovery is when muscle grows.

After 4-6 weeks, you’ll notice more energy. After 8-12 weeks, your clothes will fit differently. After 6 months, you’ll look and feel like a completely different person.

The Future Is Combined Training

The fitness industry is shifting. More people are signing up for “body recomposition” - not just weight loss. Wearables like Apple Watch and Garmin now track EPOC and metabolic rate. Apps are starting to blend cardio and strength into one plan.

Research is moving toward personalization. Scientists are testing AI that recommends workouts based on your genes, metabolism, and recovery. But for now, the best advice is still simple: move often, lift weights, eat protein, and don’t trust the scale alone.

Cardio gets you out of breath. Strength gets you stronger. Together, they get you lean, healthy, and lasting.

Is cardio or strength training better for losing belly fat?

Neither one alone is the best. Belly fat responds best to a combination of both cardio and strength training. Cardio burns the calories needed to reduce overall fat, while strength training preserves muscle and improves insulin sensitivity - which directly impacts abdominal fat storage. Studies show that people who do both lose more belly fat than those who do only one. High-intensity interval training (HIIT) is especially effective for targeting stubborn fat.

Why does the scale go up when I start lifting weights?

It’s not fat - it’s water and muscle. When you start strength training, your muscles store more glycogen, and each gram of glycogen holds about 3-4 grams of water. That’s a quick 1-2kg gain. Plus, muscle is denser than fat, so you might weigh the same or more, but you’ll look slimmer and tighter. Don’t rely on the scale. Measure waist circumference, take progress photos, or notice how your clothes fit.

Can I lose weight with strength training alone?

Yes - but slowly. Strength training burns fewer calories during the workout, so weight loss will be slower than with cardio. But it builds muscle, which increases your resting metabolism. Over time, that leads to fat loss. A 2012 study found strength training alone reduced body mass by 1.6% over 8 months - less than cardio’s 4.3%. But it added 1.4kg of muscle. If your goal is long-term metabolic health and body shape, strength training alone can work - but combining it with cardio gives faster, better results.

How much cardio should I do to lose weight?

For weight loss, aim for 150 minutes of moderate cardio per week - that’s 30 minutes, five days a week. If you want faster results, increase to 200-250 minutes. But don’t overdo it. Too much cardio can lead to muscle loss, fatigue, and burnout. The goal is sustainability. Walking, cycling, swimming, or dancing are all great. Pick what you enjoy so you’ll stick with it.

Do I need to lift heavy to build muscle and lose fat?

Not necessarily. You can build muscle and boost metabolism with light weights and higher reps - as long as you’re challenging yourself. The key is progressive overload: gradually increasing resistance, reps, or sets over time. A beginner can make gains with bodyweight exercises or resistance bands. Heavy weights aren’t required - just consistent effort. Focus on form, not how much you can lift.

What’s the best time of day to exercise for weight loss?

There’s no magic time. The best time is the one you can stick to consistently. Some people feel more energetic in the morning and burn more fat on an empty stomach, but studies show total weekly calorie burn matters more than timing. If you’re more likely to exercise after work, do it then. Consistency beats timing every time.