What cardio to lose weight?

We’ve always known it: when it comes to losing weight, people talk about cardio. And it’s true, cardio will make you “lose weight.” But be careful, cardio isn’t just about running for miles hoping to melt away fat (and often, that’s where the mistake begins).

Because ill-suited cardio, instead of boosting your metabolism, can actually slow it down. Yes, you read that right: poorly calibrated, it can actually hinder your progress and produce the opposite effect of what you’re looking for.

The two main types of cardio: high vs. low intensity

So, we have different cardio choices that will depend primarily on you, your pace, and the type of effort you enjoy making, much more than the result it will bring. (Because an effort you enjoy, you repeat. And that’s precisely the real secret to progress.)

Choosing the optimal cardio for weight loss therefore depends on your goals and especially your ability to persevere. Let’s break down the two main approaches together.

High-Intensity Cardio (HIIT)

HIIT (High-Intensity Interval Training) alternates intense efforts (85 to 95% of your maximum heart rate) and very brief recovery phases. For example, the Tabata protocol requires 20 seconds of maximum effort followed by 10 seconds of rest, repeated 8 times. This format is commonly found in CrossFit, a training method that heavily relies on interval work and intensity variation. These short but explosive sessions can include burpees, bike sprints, or step-ups.

The major advantage of HIIT is the EPOC effect (excess post-exercise oxygen consumption). Even after your workout, your metabolism remains activated for several hours, continuing to burn calories. It’s comparable to compound interest: you invest intense effort, and your body continues to “grow” that expenditure by burning more after the session. (In short, you keep gaining even after you stop sweating.)

A well-structured 20-minute workout can thus surpass a traditional cardio session in terms of total calorie expenditure. But be careful: this type of effort requires a solid physical foundation and a true sense of regularity. The “miracle” 10-minute protocols you see online often don’t exceed 70% of maximum heart rate, limiting real fat-burning effects.

Low-Intensity Cardio (LISS)

LISS (Low-Intensity Steady State) maintains a moderate effort (60-70% of max heart rate) for 30 to 60 minutes. Inclined walking, breaststroke swimming, or cycling at a constant speed are concrete examples.

Its strength lies in its ease of integration into a routine. You can listen to a podcast while walking, watch a video while cycling leisurely, or follow up a weightlifting session with it for active recovery. Unlike HIIT, it doesn’t exhaust your nervous system, allowing for regular practice without risk of overtraining.

By primarily burning fat rather than carbohydrates, LISS preserves your muscle mass. A study shows it more effectively improves fat distribution in overweight individuals. However, it takes two to three times longer to achieve a calorie expenditure equivalent to a HIIT session.

• Better suited for muscle preservation goals
• Ideal for active recovery
• Accessible to all fitness levels
• Can be combined with other daily activities

Which cardio to choose according to your main goal?

Now that we know the two main forms of cardio, you’re probably wondering: which one is most effective for you?

Let’s look at two typical profiles to better understand.

Goal #1: lose weight as quickly as possible

Want to lose weight quickly? High-intensity cardio (HIIT) is clearly your ally. By alternating phases of maximum effort and short recoveries, you can burn more calories in 20 minutes than in an hour of brisk walking.

But this efficiency has a downside: HIIT heavily taxes your nervous system and depletes your glycogen stores. Combining weight training and HIIT on the same day can impact your muscle progress… or not, depending on how you structure your sessions.

For example, in CrossFit, interval work is practiced, but sometimes with heavy loads. The result: you can gain muscle while burning fat. Why? Because calorie intake is often high alongside, and the exercises incorporate real muscle intensity. (It’s this subtle balance between load, nutrition, and recovery that makes all the difference.)

However, for someone starting out, this type of training will inevitably require a lot of energy. HIIT is demanding: it must be measured, respected, and given time to work without rushing. (It’s better to go gradually than to burn out in the first week.)

Goal #2: lose fat while preserving muscle mass

So, you’ve understood, if HIIT allows you to lose weight very quickly. LISS offers a more gradual, slower loss, but often more stable over time. And above all, it allows you to better preserve your muscle mass. (Provided, like with HIIT, you do some weight training on the side.)

Unlike HIIT, LISS doesn’t deplete your energy reserves. It helps you burn calories without tapping into your muscles, making it a perfect option to refine your silhouette without compromising your gains.

This type of effort also promotes active recovery between two more intense sessions. It helps you maintain good circulation, better oxygenation, and thus constant progress. To track your progress and adjust your training, use our IMM calculator.

Between these two approaches, a compromise exists: combining 1 to 2 HIIT sessions with 2 to 3 LISS. But this strategy is reserved for experienced practitioners. Beginners should prioritize LISS, a solid foundation for progressing without discouragement.

Remember the essential equation: a controlled calorie deficit remains key. Your best ally is the cardio you practice without frustration, week after week.

The mistake not to make: neglecting strength training

Well, we’ve talked a lot about cardio for weight loss, but one of the biggest mistakes many people make is neglecting strength training. It’s actually very simple to understand: the more muscle mass you have, the more energy your body needs to function daily.

Every 500 g of muscle burns about 100 kcal per day, at rest. Yes, you read that right: even without doing anything, your body consumes more if you’re muscular. Result: you may not necessarily lose more weight on the scale, but you are leaner, more toned, because your metabolism works for you all the time.

The best way to preserve this muscle is simply to do strength training. Only doing cardio (especially LISS) will likely make you lose weight, but there’s a risk of looking what we call skinny fat: thin, but without tone or visible muscle shape.

Every time you lift heavy weights, you create micro-tears in your muscles. These small tears are normal: your body then repairs them, and it’s precisely this process that makes the muscle grow and strengthen. And this repair work also consumes energy. (In other words, you keep burning even after the session.)

So yes to cardio, but not without strength training. And conversely, strength training alone won’t be enough either: the two complement each other perfectly if your goal is to burn fat while sculpting your body.

Calorie deficit, more important than cardio

Cardio is just a lever. As its name suggests, in cardio there’s cardiac, so heart. Cardio is not primarily for weight loss, but to improve your heart health, strengthen your endurance, and support your body in its daily efforts.

Weight loss depends on one factor: burning more calories than you consume. Your body acts like a bank account: meals are deposits, energy expenditures are withdrawals. A deficit occurs when withdrawals exceed deposits, forcing the body to use its fat reserves. So you understand, whether in finances or your diet, you’ll need to carefully analyze these expenditures and deposits.

And to help you calculate all this without hassle, we have created a basic metabolism calculator which will be your initial tool to avoid starting off on the wrong foot.

So you understand, a too marked deficit (for example, 700 kcal less per day) can harm your body: fatigue, muscle loss, slowed metabolism… Opt instead for a moderate deficit (around 200 to 500 kcal per day), compatible with preserving your muscle mass. You can, for example, eliminate about 300 kcal daily through a mix of physical activity and a slight dietary reduction. Cardio enhances expenditure, but without dietary control, its effects remain limited. A sustainable deficit is always better than an extreme one-time effort.

Perseverance always wins over intensity. A light but regular deficit is more effective than a drastic diet. A daily 30-minute walk, combined with balanced meals, already creates a sustainable deficit. A professional can then help you adjust your intake according to your metabolism.

So, you got it, cardio without a good diet for weight loss won’t do you… Hmm… much good.

The FAQ of “Why am I not losing weight despite doing cardio?”

Here’s a little reminder of the main reasons why you might not be losing (or no longer losing) weight despite your cardio activity.

• Your calorie deficit is no longer ensured: your body has adapted to your efforts and is burning less energy than before. Solution: reassess your intake with a reliable method (like the Harris-Benedict equations) and introduce intensity variations in your sessions. Tip: alternate between low-intensity cardio (brisk walking) and short but intense sessions (sprints).
• You’re doing too much intense cardio: too many demanding sessions increase cortisol, the stress hormone, which promotes water retention and cravings. Solution: reduce the frequency a bit, and favor gentler activities like swimming or the elliptical, which limit muscle catabolism. Tip: keep 1 to 2 high-intensity sessions per week maximum.
• You’re stressed or lacking sleep: these two factors disrupt leptin (satiety) and ghrelin (hunger), which hinders your results. Solution: sleep at least 7 to 8 hours per night and take active breaks (walking, stretching) to lower your cortisol level. Tip: avoid screens an hour before sleeping.
• You’re neglecting strength training: without muscle stimulation, your metabolism slows down. Solution: add 2 to 3 strength training sessions per week (with dumbbells or body weight). Tip: focus on compound exercises like squats or pull-ups to maximize the afterburn effect.
• You’re confusing weight with body composition: the scale can be misleading. You might be losing fat while gaining muscle. Solution: rely on more concrete indicators (waist measurement, photos) and make sure to include protein at every meal.

Calorie deficit and rate of loss

• “Effect of two different rates of weight loss on body composition and strength” (Slow loss ~0.7%/week better preserves lean mass than rapid loss 1.4%/week) DOI: DOI

Protein and muscle preservation

• “Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain” (High protein intake during a deficit favors maintenance and even gain of lean mass) DOI: DOI
• “A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training–induced gains” (Beyond 1.6 g/kg/day, benefits plateau for hypertrophy under normal conditions) DOI: DOI

Cardio, HIIT, and interference

• “Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises” (Cardio can limit strength if too frequent, especially running) DOI: DOI
• “Effects of high-intensity interval training vs. moderate-intensity continuous training on body fat” (HIIT as effective as continuous cardio, but more time-efficient) DOI: DOI