High-Intensity Interval Training (Hiit)
Why This Workout Will Burn Fat Fast

HIIT: The Cardio Workout That Will Change How You View Fat Loss
Written by Isaac

Whether you’re currently on a mission to lose fat, improve your fitness, or simply look and feel healthier, chances are, cardiovascular exercise is making its way into the picture. When someone says the word ‘cardio’ to you, what comes to mind?

Pounding away on the treadmill? Using an exercise bike in the gym? Or perhaps you think of taking in a game of squash with a fellow fitness enthusiast.

The definition of cardio exercise is any form of movement that gets your heart rate up and keeps it there for a period of time. There are many ways that you can do this, however some ways are simply more beneficial than others.

Today we’re going to talk about what may just be the most beneficial cardio method out there: high intensity interval training for women and men.

You may have heard this term tossed around before in fitness circles or in books or magazines you’ve read. Today, you’re going to learn the details of what this exercise is all about, how to do it properly, the pros and cons, and a few important things you must know before you start (don’t begin until you read these!).

Ready? Let’s me introduce you to high intensity interval training (HIIT).

What Is Hiit?

So what is high intensity interval training (Hiit) all about?

This form of exercise is going to have you alternating between periods of very intense, all out bursts of exercise with active rest periods that are usually one to three times the length.

For example, you might do 30 seconds of exercise, going as hard as you possibly can, and then back off and perform 60 seconds of active rest. Think going from a sprint to a walk.

This is then repeated, 10-20 times (or however long you want that interval training session to last), always starting with a brief warm-up and finishing with a cool-down.

Woman doing HIIT workout

Think about which exercise you enjoy doing!

Your work intervals will typically range from 15 seconds up to 60 seconds in length, however take note that the shorter the interval, the more intense it should be. If you are doing intervals of 60 seconds, you simply can’t maintain your 15 second interval pace for that long.

Blue T-shirt with Resting gym face sign

The value of rest.

This doesn’t mean they will be low intensity, but on a scale of one to ten with ten being the fastest you can possibly go, your 60 second interval may be done at around an 8 where as your 15 second interval will be done at that 10 level.

Choosing which interval length to use is all based upon your goals.

If you want to really improve speed and maximum power, use the 15 second length, while if you want to improve muscular endurance at high intensity levels, try the 60 second length.

Your rest periods will be 2-3 times as long. The more intense the interval, the higher the ratio needs to be.

Use the following as a good guideline for structuring your intervals.

  • 15 second interval/45 second rest interval – repeat 10 times
  • 20 second interval/60 second rest interval – repeat 8 times
  • 30 second interval/60 second rest interval – repeat 6-8 times
  • 45 second interval/60-90 second rest interval – repeat 6-8 times
  • 60 second interval/60 second rest interval – repeat 6-7 times

Keep in mind the total number of repetitions you do will be dependent on your overall fitness level, so feel free to adjust those accordingly. Generally speaking though, these workouts should never be lasting much longer than 15-20 minutes. If they are, that’s a sign you aren’t pushing yourself as hard as you should be during them.

Which exercise is best to perform HIIT with? The answer to this entirely depends on your goals and preferences. The only one true requirement that the exercise must meet is that you can accelerate and decelerate quickly.

For example, doing intervals on the treadmill is less than ideal because by the time you get that treadmill up to your top speed, half your interval time is already over. Sprinting outside would be a much better option.

Best HiiT Workout Exercise Examples

  • check
    Outdoor sprinting
  • check
    Running stairs (using a normal staircase)
  • check
    Spinning bike
  • check
    Jump rope
  • check
  • check
    Clean and press (using a lighter weight)
  • check

Think about which exercise you enjoy doing and which targets the primary muscles you want to work. It’s important that whatever exercise you choose, you’re comfortable as well as that will ensure that you are able to exercise at maximum intensity level.

7 Benefits Of High Intensity Interval Training

Now that you know what interval training is, what benefits does it offer? Let’s look at a few of the major advantages of including this workout in your routine.

1. Improved Resting Metabolic Rate

Perhaps the biggest benefit that leads most people to try HIIT is the fact it improves your resting metabolic rate. When you do HIIT, you’ll burn more calories not only during the workout, but for hours after the workout is completed.

Man resting at a gym

Don't forget to take time to rest.

This is a process known as excess post-exercise oxygen consumption (EPOC). When this occurs, the body will spend a great deal of energy after the exercise is completed, returning the body back to a state of homeostasis.

You create what’s called a ‘metabolic disturbance’, meaning you place so much stress on the body that it leads to a rise in all the normal reactions taking place. The end result is you expend calories at an increased pace for up to 48 hours after the workout is completed, giving you an edge on fat burning.

Studies confirm this. Research published in the Pars Journal of Medical Science noted that when test subjects performed 3 interval sessions per week for 6 weeks, they showed decreases in total body fat percentages, body mass index’s (BMI), as well as waist to hip ratios.

Additionally, it’s been shown that regular HIIT also improves total body and skeletal muscle capacity for fatty acid oxidation during exercise as well. This means that you may be better able to burn fat during exercise after completing HIIT sessions.

2. Decreased Gym Time

Feel like you never have enough hours in the gym? You aren’t alone. Lack of time is one of the top reasons that people state they have for not being able to perform their workout sessions.

Fortunately, HIIT helps you get past that. Because these workouts are so very intense, you’ll be in and out of the gym in no time. Including the warm-up and cool-down, you’ll be looking at no more than 20-30 minutes.

So not only are you reaping better benefits than you would doing a very low intensity, long duration workout, but you’re spending less time overall exercising.

3. Enhanced Lean Muscle Mass Retention

If you’re looking to lose weight, one key component of success is eating in a hypocaloric state. If you don’t consume fewer calories than you burn off daily, you’ll struggle to see any progress at all. Sadly, this puts you at risk for the loss of lean muscle mass tissue.

Dog running on a beach

Lean and mean!

Many people who diet lose a combination of fat mass as well as lean muscle mass. HIIT can help prevent this. When subjects perform either HIIT or lower intensity, long duration exercise, those who do HIIT lose less muscle overall.

This is important to note because in addition to making you appear more fit, your muscle mass tissue is highly metabolically active and will help you maintain a faster metabolic rate 24/7.

Those who lose too much lean muscle while dieting often find it becomes very challenging to maintain the weight loss because once they stop dieting, their metabolism has slowed down so significantly.

4. Improved Cardiovascular Fitness Level

While all those hours spent on the cardio machines will help you improve your cardio fitness level, HIIT really stands above the rest.

With this type of training, you’ll improve your VO2 max level, which represents how much total oxygen your body is able to use during intense physical exercise. As this improves, you’ll notice you become far less fatigued while doing everyday activities.

Regularly performing HIIT, despite the fact you are resting so often during the workout session will still help to lower your blood pressure levels, decrease bad cholesterol levels, and lower your risk for cardiovascular disease.

One study published in the Applied Physiology, Nutrition, and Metabolism journal noted that after just 3 sessions of less than 10 minutes per week, test subjects were noticing a reduction in disease risk after just a few weeks time.

5. Elevated Strength And Power Output

One thing you can be sure of about HIIT is that it’s not easy. You’ll have to go from very little effort to maximum effort in mere seconds, which will really go a long way towards boosting your overall strength and power output.

This can provide excellent transfer benefits if you participate in any team sports (as one trait of almost all successful athletes is that they are very powerful) as well as to any other fitness related activities you are doing such as weight lifting.

Simply put, HIIT training helps you become a more well-rounded athlete.

6. Improved Mood

Ever notice the high you get when you walk out of the gym after an intense weight lifting workout? That same feeling can be achieved with HIIT as well. When you do this form of exercise, your body will release feel-good endorphins in the body, which help combat stress and boost your mood.

Black and white photo of a smiling woman

Feeling good?

Stress is one of the biggest hindrances on optimal health in today’s world, so if you are experiencing it, HIIT is a great solution.

7. Increased Bone Density

Finally, provided you are selecting a weight baring form of exercise to perform while doing HIIT, you’ll also experience increased bone density benefits as well. Regular HIIT training can decrease your risk for stress fractures and osteoporosis.

While this may no be so much of a concern now, it will be later on as you get older. Studies have illustrated that adding a high intensity resistance training program to a diet plan helped subjects both increase their lean mass and prevent a decline in bone mineral content.

As you can see, there are many great benefits to including HIIT training into your workout program. When you stack it up against long duration, moderate intensity exercise, it simply comes out ahead.

High Intensity vs Low Intensity Training

After covering all the good about HIIT exercise, does this mean there is no place for low intensity training (LIT), defined as moderate intensity exercise performed for 20-60 minutes? Not necessarily. In some cases, LIT can be a superior choice.

The first case is if you are injured in any way. Because high intensity training is so intense, it’s much more likely to aggravate an injury so using a lower intensity form of training is a far superior choice.

HIIT or a nice, leisurely walk?

The second time LIT may be a better option is if you are already doing a number of other high intensity workouts. For instance, if you are hitting the weights hard four days per week, adding another couple days of HIIT training may be too much for your body to handle. You still need sufficient time to recover during the week and adding some lower intensity workouts to your protocol is a smart move.

In this scenario, doing a couple LIT sessions can keep your cardio up without overly taxing your body.

Finally, the last time you may want to shy away from HIIT is if you’ve never exercised before. While there is definitely a way to approach HIIT for beginners (which we’ll talk about in a second), if you don’t have any cardiovascular training under your belt, start off with LIT for a while first and then progress from there.

Tabata Training: HIIT Cardio on Overdrive

One particular variation of HIIT that’s worth mentioning here is referred to as the Tabata method and is an ultra-short, 4 minute long workout that basically takes HIIT to the next level.

With this workout, rather than using rest intervals that are two to three times as long as your work interval, your work interval will be the longer of the two.

Group of adults participating in a fitness class.

This particular HIIT cardio workout is not for those who are inexperienced.

With this protocol, you’ll structure your workout as follows:

  • check
    20 Seconds On
  • check
    10 Seconds Off
  • check
    Repeat 8 times

This takes four minutes total and will be the most intense four minutes of your life. Again, start with a warm-up and finish with a cool down and be sure to choose compound movements that allow for fast acceleration.

This particular HIIT workout is not for those who are inexperienced however. Be sure that you have at least 6 months of standard HIIT experience before you progress to this method.

If you are looking for maximum fat burning and the shortest workout possible however, it’s a great option to choose.

4 HIIT Advice For Beginners

If you are a beginner who wants to get involved with HIIT cardio training, there’s a specific approach to use. You’ll be best off easing yourself into it, gradually adding an interval or two into your standard cardio session.

Focus on picking up the pace for 30-60 seconds and then back down to your normal working pace until you feel fully recovered. Then repeat this process, doing it as often as you can. Over time, focus on adding more of these intervals.

Once you can do 5-6 intervals per session, then you are ready to move into a full-blown HIIT protocol as described above. Try starting with 30 second intervals, using 60 or even 90 seconds of rest in between.

From there, you can either choose to increase the intensity of your intervals, going for 15 seconds instead or increase the duration, moving to a 60 second interval to work on your muscular endurance.

Beginners should aim for no more than two HIIT cardio workouts per week to ensure they are giving their body enough recovery time between workouts. Don’t fall into the trap of doing too much, too soon.

1. Fuel Up Before Each Session

Does all of this have you excited to get going immediately? Hold on for a brief second! There are a few things you need to know to make your transition into HIIT both comfortable and successful.

It’s important that you treat every HIIT session you do like a weight lifting workout.

Attempting this on an empty stomach would not be a smart move as your body needs glucose in order to exercise at the intensity you’re going for here.

Try a simple snack of around 200 calories about 60 minutes prior to the workout.​

Stock up on some healthy, fuel-filled calories before you go hard on the HIIT.

Think a banana and some Greek yogurt, half a chicken sandwich, or a small bowl of cereal with low fat milk.

2. Avoid HIIT Workouts Before/After Leg Day

Let’s face it, leg day is hard. Don’t make it any harder on yourself. Avoid doing HIIT on the same day you have a leg workout scheduled. Instead, try and separate them by at least one day for rest. This will also help you avoid attempting HIIT while experiencing post-leg day soreness.

3. Gauge Your Recovery Often

Because HIIT workouts are so intense, it’s much easier to overtrain yourself doing it. Be sure to gauge your recovery often. Are you feeling recovered? Do you go into each workout full of energy?

If the answer is no, you may be doing too much. Consider backing off slightly, reducing how many sessions you are doing or the duration of the workouts.

4. Defend Against Injury

Finally, your injury risk during HIIT is much higher due to this intensity. Always watch that you are using good form on whatever exercise you are doing and never skip your warm-ups. Both of these factors can help greatly decrease your risk of injury and becoming sidelined.

Plush toy of a frog

Never skip your warm-ups!

Take care or you won’t be doing HIIT for long.


So there you have all the main points that you need to know about high intensity interval training. It’s one of the best forms of exercise you can add to your workout program provided you are of the fitness level to do so.

It’s quick, it’s great for fat burning, and once you get started, you might just find it’s a lot of fun as well.

About the author


I’m a personal fitness trainer and nutritionist living in sunny Indianapolis, IN. I’ve spent the last 8 years staying at the forefront of the health and fitness industry. In that time, I’ve helped hundreds of people shed the excess weight and get into shape, maintaining their healthy new lifestyle through proper training and eating habits.