By now I’m sure you’ve heard about high-intensity interval training (HIIT). It’s one of the best exercise protocols for fat loss, as it allows you to get more work done in less time all while burning the most fat possible.
HIIT combines short periods of intense exercise with short periods of rest. For example, one minute of sprinting followed by one minute of walking, and then repeating that cycle for 20 minutes.
You don’t have to do sprints though. Any exercise that works a large part of the body can be adapted to a HIIT protocol.
I personally use HIIT with many of my clients with great success. And I have a feeling that if you’re physically capable of doing HIIT, you’re going to be hooked for life.
Benefits of High-Intensity Interval Training (HIIT)
So why is HIIT so effective for fat loss?
Besides the numerous intangible benefits like added variety, enjoyment, time efficiencies, and the fact that you don’t need gym equipment to do it, there are also many scientifically proven benefits to HIIT.
If you’ve ever wondered how HIIT promotes fat loss, here’s how it works its magic…
Improved Insulin Sensitivity
Insulin sensitivity, or how well your cells respond to insulin, has a big impact on how well you tolerate carbohydrates, and whether those carbohydrates will affect your ability to mobilize fatty acids.
Reduced insulin sensitivity means you need more and more insulin to do the same job. And since insulin is a storage hormone, when it’s high, it’s more difficult to lose fat.
Following just 2 weeks of HIIT, in which there was a total of only 15 minutes of exercise, insulin sensitivity was improved by 23% .
Produces the Afterburn Effect
Excess post-exercise oxygen consumption (EPOC), is the increased oxygen your body uses after an intense workout to erase its oxygen debt. It uses this oxygen to return the body to homeostasis.
That means it uses additional calories to perform tasks such as muscle repair and replenishment of fuel stores. EPOC is better known as the afterburn effect, which is the process of burning extra calories long after your workout is over.
When comparing HIIT to low-intensity exercise, your exercise intensity positively affects both the magnitude and duration of EPOC . In other words, the greater your intensity, the greater the afterburn effect.
Specifically Targets Stomach Fat
Yes, we all know that you can’t target fat loss per se. However, that’s not what we’re talking about here. Doing sit-ups isn’t going to target belly fat.
However, there are things you can do that will change the way you store and mobilize fat. The way you store fat is determined by many factors – genetics and hormones being two big ones. And the type of exercise you do affects your hormone profile.
Doing HIIT can create a metabolic environment that stimulates a higher proportional release of abdominal fat. You still lose fat all over, but a higher proportion comes off in the midsection.
High-intensity interval exercise three times per week for 15 weeks was compared to the same frequency of steady-state exercise, and only HIIT produced significant reductions in total body fat, subcutaneous leg and trunk fat, and insulin resistance .
Improved Vo2 Max
VO2 max is your body’s max capacity to transport and use oxygen during exercise. It is a great measure of physical fitness. Generally speaking, the higher your VO2 max, the better your fitness level. A higher VO2 max also means that you can exercise at greater intensities for longer periods of time.
Creation of New Mitochondria
Mitochondria are little cell powerhouses that produce energy (ATP). In simple terms, they take the fat and carbohydrates you either eat or store and convert them to usable energy. The more mitochondria you have, the better your body utilizes the calories you consume.
Boosts Favorable Hormones
High-intensity interval training does more than just burn calories. It primes your body for fat loss by creating a favorable metabolic environment.
Internally, your body undergoes many hormonal changes in response to intense training. Specifically, HIIT boosts growth hormone and testosterone levels after just 10 minutes, and the amount secreted is correlated to your exercise intensity [10, 11, 12].
Growth hormone and testosterone are a potent combo for both fat loss and muscle growth. Engaging in HIIT will provide you with this amazing benefit.
Burns More Total Fat Compared to Endurance Training
Did you know you can burn more fat doing HIIT than your typical steady-state endurance training, even when burning a fraction of the calories? It’s true.
A study comparing a 15 week HIIT program to a 20 week endurance-training (ET) program showed that despite its lower energy cost, the HIIT program induced a more pronounced reduction in subcutaneous fat compared with the ET program .
Builds Muscle While Losing Fat
Many people say you can’t build muscle and burn fat at the same time. While it can be difficult to put on a large amount of muscle mass while in a calorie deficit, you can certainly accomplish both goals concurrently.
In fact, a 12 week HIIT program has been shown to increase lean body mass, while at the same time reducing total body fat, abdominal and trunk fat, and visceral fat .
The additional muscle will pay dividends by increasing your resting metabolic rate so that you’re burning extra calories at all times of the day. Build muscle and lose fat, all while exercising for less time. Seems too good to be true, but it is.
Increased Capacity for Fat Oxidation
During exercise our bodies undergo all kinds of chemical reactions and stress adaptations. Our bodies literally change from the inside out. During HIIT specifically, we make changes to our physiology that enable us to burn more fat.
Just seven sessions of HIIT over 2 weeks induced marked increases in whole body and skeletal muscle capacity for fatty acid oxidation during exercise in moderately active women . HIIT causes changes to your body that increases its ability to burn fat.
Sample HIIT Workouts
Now that you know why high-intensity interval training is so effective for fat loss, it’s time to look at some real world applications of it.
To better help you visualize what a HIIT workout looks like and how to structure the exercises and work/rest intervals, I’ve put together a bonus.
Click here to access 10 different HIIT workouts. I’ve broken them down into beginner, intermediate, and advanced, and also included bodyweight, kettlebell, weights, and traditional cardio options.
Tips for Making HIIT More Effective
While engaging in HIIT it’s important you follow some simple guidelines in order to get the most out of its fat loss qualities:
- Keep the intensity high during your work intervals. Many of the fat loss benefits of HIIT come from the higher intensity levels.
- To progress with HIIT you want to work towards increasing the length of your work intervals while decreasing the time of your recovery intervals. If you’re combining strength training with HIIT then you can also work towards using more weight or doing more reps.
- To keep HIIT workouts from getting stale you can vary the work/recovery intervals. For example, instead of doing 1 minute of work followed by 30 seconds of recovery, you could do 3 minutes of work with 1 minute of recovery.
- Use exercises that incorporate as much of the full body as possible. The more muscles you can work during HIIT the more you’ll receive its fat loss benefits.
- Since you’re training at a high intensity you also need to be focused on recovery. Keep HIIT workouts separated by 48 hours of rest to allow for muscle and nervous system recovery.
- Eat to fuel your workouts. Since intensity drives progress you want to make sure you’re eating for performance. A small meal 60-90 minutes before your workout can be beneficial.
So what do you think? Have you ever experimented with high-intensity interval training? How did it work out for you?