LISS Cardio vs. HIIT Exercise: Which Is Better For Burning Fat?

Dave Smith

By Dave Smith

Social media has changed the way we get advice about exercise. Nowadays, any personal trainer (or anyone with a great body, really) can easily put their workouts on display for everyone to see. The result? 

A lot of really fit "Insta-famous" people are teaching us that we need to exercise like they do. If you want to be fit, lean, and healthy, you have to endure gruelling workouts; the more intense, the better.

But, is it true?

Are all those pop-fitness workouts really the best way for you to change your body? 

Dave Smith
Dave Smith

Chosen as Canada's Top Fitness Professional

In my nearly 2 decades as a personal trainer and weight-loss coach, I've seen too many people invest time, energy, sweat, and tears into exercise that is never going to give them the results they want.

My goal with this article is to compare two opposing styles of exercise, HIIT and LISS. Which is really better for fat-loss?

After reading this, you will understand how each type of exercise works, the pros and cons of each, and which one is going to help you lose weight and build the body you'd like to have.

Ready to get started?  

What Is HIIT?

HIIT stands for High Intensity Interval Training. There are many ways to perform a HIIT workout, but they all stem from the same 2 principles:

  1. Alternate between short work and rest periods
  2. Work periods are intended to be "all-out" exercise

Practically, this might mean that you sprint on a treadmill as fast as you can for 30 seconds, then walk for 30 seconds before sprinting again. This would be an example of a 1:1 HIIT ratio (i.e. you doing 1 period of hard work followed by an equal period of rest).

The work to rest ratios can be changed to form a huge variety of workout routines. One popular example is called Tabata training. It uses 20-second work periods, followed by a 10-second rest. This would be a 2:1 HIIT sequence. And here's a third HIIT timing ratio example: 

HIIT Pros: Why People Love HIIT

HIIT has become a staple for personal trainers, in boot camps, and even for people who want to get in shape at home. What's the big deal?

There are 4 primary reasons why people seem to love HIIT: 

1. HIIT Provides Shorter Workouts

Who has time for long workouts these days? If I offered you a workout that produced great results in half the time, how could you refuse? That's the primary draw to HIIT workouts:

HIIT takes less time.

One research study (of many) showed that a workout consisting of four 4-minute HIIT intervals outperformed traditional long-distance training by as much as 10% when looking at the cardiovascular benefits.

Imagine that: Put in 16 minutes of work and get better results than if you had gone jogging for double or triple the amount of time. Pretty incredible.

2. HIIT Burns More Calories

HIIT also does more than just strengthen your heart. It burns calories. HIIT burns a lot of calories.

Research shows that HIIT workouts burn between 6-15% more calories than traditional steady-state exercise. Some of these calories are consumed during the workout itself, but not all of them. HIIT triggers an effect known as Excess Post-exercise Oxygen Consumption (EPOC).

EPOC simply means that your body is restoring itself to pre-exercise levels. Because HIIT is so, well, intense, your body has to work harder to replenish itself after the workout is finished. This replenishment period requires energy, therefore you may continue to burn calories for hours after your workout is complete. A great bonus!


This graph depicts how long EPOC can last after an intense exercise session

3. HIIT Improves Athletic Performance

Athletes love HIIT because it provides them with game-style conditioning. Think about sports like soccer, basketball, football - they all require short bursts of energy followed by periods of recovery.

HIIT does a great job of training many aspects of an athlete's game. As we've discussed, it improves cardio conditioning, but it can also be used to increase speed, quickness, and power, which are all elements of fitness that will improve an athlete's performance.

4. HIIT Is Very Accessible

People have gravitated towards HIIT because leading companies in the fitness industry have made it so accessible.

At-home workout programs like P90-X or Insanity were built squarely on HIIT exercise. The same goes for CrossFit. It's exciting. It's competitive. It's intriguing. And, it has become a viewing stage from which HIIT can be promoted to the masses.

When average Joe or Jane sees the physiques of famous HIIT users, it can be hard to resist the urge to try if for themselves. Also, the fact that many HIIT workouts require no equipment makes it even easier for anyone to step up and give it a try.

HIIT Cons: Why HIIT Isn't For Everyone

Right now you might be thinking that HIIT sounds pretty good. Burn more calories in less time, while becoming more athletic like the CrossFit pros you see on TV? Sign me up, right?

Well, there are some drawbacks to HIIT that might not get mentioned as often as they should. Here are 4 main issues to consider:

1. HIIT Is a Lot of Work

Do you enjoy sprinting as hard as you can, even if it's just for a 30 seconds? While the benefits sound appealing, many people don't enjoy it or don't have the resolve to push themselves that hard. 

It's one thing if you're an athlete looking to improve your performance at any cost, but it's a completely different story if you're just trying to drop a few pounds and stay in shape.

Remember, true HIIT training requires you to push with 100% effort during work periods. That's something many people aren't interested in doing. HIIT might be an option now and then, but for most, it's too much mental and physical effort to use HIIT regularly.

2. HIIT Can Be Dangerous

While the health benefits of HIIT are well-documented, there's a flip side to the coin. HIIT can be very dangerous, especially for people who aren't in tip-top shape when they first give it a try.

One study found instances of a muscle and kidney condition called rhabdomyolysis among newcomers to HIIT. This condition is often seen in military training camps where soldiers push their bodies to the extreme. With HIIT, exercisers experience nausea, fever, and vomiting before being diagnosed with the stress-induced rhabdomyolysis:

The more common danger that comes with HIIT is injury. Since the HIIT embraces a "work till you drop" mentality, it becomes easy for a person to lose proper exercise form as the body approaches exhaustion. Poor form leads to injury.

In addition, HIIT is often performed in large group exercise classes where it's difficult for an instructor to give each participant the coaching they might need. The same goes for at-home HIIT programs. No coaching equals less safety.

Finally, there is often a level of competition associated with HIIT. When someone tries to keep up with others around them, the risk of injury goes up.

3. HIIT Requires More Recovery Time

Taking your body to its exercise edge is stressful on your muscles, joints, and even your heart. Your body needs a lot more rest time after a HIIT session than it might after less-intense exercise.

Some researchers suggest that HIIT be performed no more than 40 minutes in total per week, and that at least 24 hours of recovery be built in between HIIT and your next workout.  

Unfortunately, many people think a quick 20-minute HIIT workout wouldn't be that taxing on the body: "It's only 20 minutes! I'm fine." But that couldn't be further from the truth. Heading back to the gym the following day increases the risk of overuse injury (see #2 above).

4. HIIT Can Cause Hormonal Issues

Pushing your boundaries during a HIIT workout can help you condition your body to become stronger - a good thing. But training this hard is physically stressful, and stress is not something most people need more of.

When you exercise at your maximum capacity, production of several hormones increases; growth hormone, testosterone, endorphins, epinephrine (adrenaline), norepinephrine (noradrenaline), cortisol, and aldosterone are the most notable. 

Your adrenal glands produce cortisol to tell your body to break down muscle in order to generate more energy to power your muscles. This is necessary during exercise, especially HIIT, since your muscles need energy to move.

The problem arises when someone who is already under a lot of stress (e.g. emotional stress, relational stress, environmental stress, etc.) adds stressful exercise like HIIT to their routine. This can result in overactive adrenal glands, overproduction of cortisol, and eventually a condition known as adrenal fatigue, which can cause poor sleep, low energy, weight-gain or weight-loss, and a host of other undesirable symptoms.

What Is LISS Cardio?

LISS stands for Low-Intensity Steady State, or Low-Intensity Sustained State, depending on who you talk to. LISS is simple: Do any aerobic activity at low intensity for a prolonged time period.

What does "aerobic activity" mean? Well, that's up to you. The goal is to get your heart rate elevated (slightly), so you can walk, cycle, swim, dance, or do anything else that gets your blood pumping (a bit).

What does "low intensity" mean? Ideally, your heart rate will stay between 50-60% of your max heart rate. To calculate your max heart rate, subtract your age from 220.

For example, I'm 38 years old, so 220 - 38 = 182. Sticking between 50-60% of my max heart rate means I would aim for 91 to 109 beats per minute. This certainly counts as exercise, but it's definitely no HIIT workout!

What does "prolonged time period" mean? LISS cardio workouts typically last between 30 to 60 minutes.

LISS Pros: Why You Need More LISS Cardio

When compared to HIIT exercise, LISS cardio might not sound super exciting, but there are 5 reasons why it's worth taking a second look at:

1. LISS Cardio Will Get You Results

You don't have to move quickly in order to burn calories. In fact, the speed at which you move is far less important than the distance you travel, as you can see in this chart:

LISS Cardio Calories Burned

Increasing your walking speed has little impact on the number of calories you burn over the same distance

Additionally, you have likely heard that exercising at a lower heart rate will put you in the "fat-burning zone," whereas exercising at a higher heart rate will be more beneficial for cardiovascular conditioning.

The concept of the "fat burning zone" is often misunderstood, but is actually very simple to understand: When you exercise with less intensity, your body is able produce energy aerobically (i.e. using oxygen), which allows it to burn a higher percentage of fat for fuel.

This doesn't mean that you'll burn more fat in total, but LISS cardio will put you in a heart rate range that burns a greater percentage of calories from fat as you exercise. You don't need to move quickly to burn calories or fat.

2. LISS Cardio Is Super-Safe

Unlike HIIT, which often relies on fast movements like sprinting and jumping, LISS cardio is slow and under control. That's why walking is deemed one of the safest forms of exercise you can choose.

Nothing stops progress like injury. What good is HIIT exercise if a pulled hamstring, bad knees, or a sore back forces you to take time off. All of that work you put in can quickly be undone by an injury or two. LISS is a much safer alternative.

3. LISS Cardio Requires No Recovery Time

As we looked at earlier, HIIT exercise can only be done in small doses, ideally for no more than 40 minutes per week. This might give you enough time for two workouts before your body can't safely handle any more HIIT.

LISS, on the other hand, is gentle enough that you can do it every single day. Because your muscles and joints aren't taking a beating, and because your stress hormones aren't being triggered, you can exercise daily without worrying about recovery time

This is very helpful for anyone who thrives on having distinct routines. You can build a habit of doing daily LISS at a time that works perfectly for you.

4. You Can Do LISS Cardio Anytime, Anywhere

LISS is the ultimate "convenience" exercise. You don't need a gym. You don't need any equipment. You don't need an instructor. You can just get up and move whenever you have time.

For example, if you have an hour for lunch break, it might be tough to schedule a run. You'd have to change your clothes, and you'd be all sweaty afterwards. You would need to shower before heading back to work. The process is just inconvenient enough that it could be easy to talk yourself out of running most days.

LISS cardio removes those barriers. Slip on some good walking shoes and head out the door. Exercising at 50 to 60% of your max heart rate likely won't have you sweating too much, so you can easily return to work without needing to shower. Any 30-minute window is a perfect time for LISS.

5. You Are More Likely to Stick with LISS Cardio

Not only will LISS cardio help you avoid injury, but it will also provide you with a form of exercise that you can literally do for life.

As we discussed, HIIT exercise is not only physically taxing, but it requires a lot of mental fortitude to push your body to its max capacity. There are many days, and stages of life, when that sort of "Go go go!" exercise is not going to be what you want to put yourself through.

Here is one of my favourite HIIT cardio workouts. It's great, but I can only do it on days when I'm full of energy, otherwise it's just too mentally and physically demanding:

Sure, there may be days when you don't want to do LISS either. Going for a walk when it's raining or getting into the pool on a cool day aren't easy, but research shows that people enjoy lower-intensity exercise much more than HIIT.

And, do you know what type of exercise is going to get you the best results? The type that you will do with consistency. If you enjoy LISS, you're much more likely to stick with it for life.

LISS Cons: Why LISS Cardio Isn't the Perfect Exercise Solution

LISS is sounding pretty good right now, isn't it? Well, there are some drawbacks that you need to understand before you dedicate yourself to LISS training:

1. LISS Cardio Leads to a Plateau

One of my favourite exercise mantras goes like this: "In order for your body to change, you need to give it a reason to change."

A lot of people get stuck in an exercise rut. They do the exact same routine, week after week, and then wonder why they never see any physical improvements in their body. 

The Progressive Overload Principle states that you must give your body new challenges in order to force it to adapt and change. In other words, if you want to lose weight and to tone your body, you have to do something different from what you're already doing.

This is the major downfall of LISS. It's hard to continually challenge your body in new ways. Here's an example:

  • Say you start walking for 30 minutes every day. This is a fantastic choice! It doesn't take long before you start losing some weight, your clothes start fitting better, and you feel great. 
  • Weeks go by and you're still walking 30 minutes every day, but you've noticed that you're not losing weight any longer. Your body has gotten used to doing that 30-minute walk each day.
  • No problem. You begin walking for 45 minutes. That will give your body a new challenge and will spark the weight-loss you're looking for!
  • It works... for a while. But then you hit another plateau.

What's next? Are you going to walk for an hour each day? Then what? Two hours?

Because LISS is limited in its variety, your body is going to become accustomed to your exercise routine and will eventually stop changing. With LISS, you will hit a plateau that will be difficult to overcome.

2. LISS Cardio Does Not Create EPOC

Remember EPOC? (If not, see the benefits of HIIT section above)

Excess Post-exercise Oxygen Consumption occurs after HIIT exercise or strength training workouts. Your body continues to burn up extra calories for hours after exercise as it replenishes itself. This is sometimes referred to as The Afterburn Effect

LISS does not create EPOC. 

Because the intensity of LISS is relatively low, your body is able to "keep up" as you exercise. There is no oxygen or energy deficiency that needs to be recouped when you finish, so your metabolism is not elevated for prolonged periods of time after you finish exercise. Bummer.

3. LISS Cardio Reduces Your Metabolism Over the Long-Term

Every pound of muscle that you carry on your body has a tremendous metabolic effect. Research shows varied results, but it's somewhere between 24-50 calories per pound per day. 

That might not sound like much, but it really adds up. If you added just 5 pounds of muscle to your body, you'd burn up to 1,750 calories per week without doing any additional exercise. That's significant. 

liss vs hiit metabolism

Marathoners or Sprinters: Based on their muscle, which runners do you think have higher metabolisms?

The opposite also holds true: If you lose 5 pounds of muscle, your metabolism will decrease up to 1,750 calories per week. 

LISS, while great for your cardiovascular conditioning, will not help your body build muscle. In fact, too much LISS will deteriorate your muscle.

You may lose weight initially, but because your muscle and metabolism are in decline, it will be hard to continue losing weight in the long-term on a LISS-only exercise program.


Without specific action to build or maintain muscle mass, metabolism steadily drops with age

This becomes especially problematic as you age because your metabolism will already be in a natural decline. Doing too much LISS can speed up the process of your metabolism slowing down.

4. LISS Cardio Doesn't Improve Athletic Performance

For those who are looking to perform better athletically, LISS is certainly not your best exercise option.

Yes, LISS can be used to help you actively recover after more intense workout sessions, but it will not improve your speed, strength, acceleration, or other athletic skills. More intense and more varied training is needed for athletic conditioning.

HIIT vs. LISS Conclusion

We've just covered a lot of information about the pros and cons of HIIT and LISS exercise. Let's look at a summary for each:

HIIT Exercise

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    Shorter Workouts
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    Burns More Calories Through EPOC
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    Improves Athletic Performance
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    Can Be Done Anywhere
  • Is Not Enjoyable for Many People
  • Can Lead to Injury
  • Requires a Lot of Recovery Time
  • Can Negatively Impact Hormones

LISS Cardio

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    Gets Weight-Loss Results
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    Is Very Safe Even for Beginners​​​​
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    Requires No Recovery Time
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    Can Be Done Anywhere
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    Is Enjoyable for Most People
  • Leads to a Plateau
  • Does Not Create an "Afterburn" Effect
  • Can Slow Down Your Metabolism
  • Doesn't Improve Athletic Performance

HIIT and LISS are nearly complete opposites. Some of the best benefits of HIIT are limitations of LISS and vice versa. It's up to you to determine what your goals are and how you want to approach those goals.

Low-Intensity Fat Loss (LIFL):
Your Alternative to HIIT and LISS

There is a hybrid form of exercise known as Low-Intensity Fat Loss (LIFL) that is gaining in popularity. It combines the calorie- and fat-burning potential of HIIT with the safety and gentleness of LISS. Here are the benefits of LIFL:

LIFL Exercise

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    Shorter Workouts
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    Burns More Calories Through EPOC
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    Can Be Done Anywhere
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    Gets Weight-Loss Results
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    Is Very Safe, Even for Beginners
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    Is Enjoyable for Most People
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    Speeds Up Your Metabolism
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    Doesn't Require a Lot of Recovery Time
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    Does Not Lead to a Plateau

If you're training for athletic competition, HIIT still may be your best option. But, for anyone looking to lose weight, get a toned body, and be all around more healthy, LIFL will definitely get you where you want to be. 

>> CLICK HERE to learn about the uniqueness of LIFL and how you can start using it today to safely burn more fat and change your body.