Last Updated 3 years ago
High-Intensity Interval Training (HIIT), has risen to prominence lately as the ultimate trick for burning fat and the fastest way to a lean body.
The ardent supporters of HIIT believe that standard steady-state cardio is a waste of time and energy.
The belief is that HIIT can get you the results you want much faster and more efficiently.
But how much truth is in that claim?
In this article, we will try to take a more objective, sober look at the actual benefits of HIIT, based on scientific evidence.
Let’s start by getting a clearer picture of HIIT itself.
HIIT – What Exactly is It?
High-intensity interval training, also known as high-intensity intermittent exercise (HIIE) and sprint interval training (SIT), is a cardiovascular exercise strategy that seeks to optimise results by alternating short periods of intense anaerobic exercise with less-intense recovery periods.
The workout must continue until the person is too worn out and is unable to continue.
There are several HIIT workouts of various session durations, but most of them last around 30 minutes or so.
Naturally, intervals and intensity of the workout largely depend on the person’s fitness level. In most cases, the more intense the exercise, the smaller the duration of the workout.
HIIT workouts have indeed been found to improve athletic performance and increase glucose metabolism.
Several studies have also proven that it can deliver truly great results in fat loss in all parts of the body. Still, there are a few other things we need to keep into account.
HIIT – Is it for Everybody?
HIIT is very different from your typical workout. Its intensity demands high levels of concentration and determination.
In fact, several studies have pointed out that HIIT requires high levels of “subject motivation”, thus coming into the conclusion that a significant number of people couldn’t actually keep this type of training up for long.
Still, for those who are determined to follow it through, results are guaranteed, right?
Let’s see.
HIIT – Is it for Everything?
First, of all, we must make clear that HIIT is great for boosting performance and burning fat, but it is hardly a panacea.
For example, some studies have suggested that it may not prove as effective for treating obesity or hyperlipidaemia, the state of abnormally elevated levels of lipids or lipoproteins in the blood.
In addition, while HIIT produces fantastic fat burning results, it hasn’t proved so great at building muscle or improving bone mass.
Nevertheless, HIIT is indeed very effective in improving cardiometabolic health, producing similar results with those of a five-fold bigger exercise volume and time in standard aerobic exercise.
This means that HIIT can save you a great amount of time or get you faster to the desired results.
Yet, the snare of exaggeration always lurks out there.
HIIT – Some Truths you Need to Know
There all sorts of claims about the HIIT’s fat-burning efficiency and a great number of them are indeed greatly exaggerated.
First of all, studies have shown that cardio training is not exactly ideal for losing fat. This is hardly a scientific break or a stunning revelation; research done almost 30 years ago have shown that aerobic exercise barely expedites weight loss in people following a low-calorie diet.
Sure, there are benefits in other areas, but when it comes to fat burning and weight loss, cardio’s contribution is much inferior to that of a well-balanced diet.
Let’s dig a little deeper.
The famed HERITAGE Family Study, one of the largest and most reliable studies on the matter, assessed the results of a five-month exercise program in more than 500 adults and found that after 60 workouts, the average amount of fat loss was no more than a couple of pounds.
The conclusion seemed inevitable: researchers admitted that cardio exercise does not actually play such a big role in weight loss as is generally believed.
If we want to be more accurate, we would say that aerobic exercise can help greatly in weight loss, but only if you devote a significant amount of time in it.
For example, another study focused on obese adults that walked or jogged for 60 minutes on a daily basis.
They did lose, on average, 13 pounds of fat, which is pretty impressive. Still, they had to do that every day for three months!
Another factor is the extra bodily weight they carried around, which obviously demanded much more energy than it would in a standard-weight person.
So, one thing you have to keep in mind is that, while cardio is indeed beneficial to our health and body, is not the best way to lose weight.
HIIT proponents claim that it is the best way to lose fat, because of the “afterburn effect” it induces – that is, the fact that the body continues to burn calories at an accelerated rate after the workout session is concluded.
But this “afterburn effect” has come under scrutiny lately.
In a study performed by a research team of the Colorado State University, it was discovered that, on average, the number of calories burned during a HIIT workout and “afterburn effect” was 226.
In addition, the researchers did not spot any impact on resting metabolism 23 hours after the workout, which means that all calories were burned during and right after the HIIT training session.
Sure, you may say, but isn’t that much more effective than steady-state cardio? Well, yes, but not as much as HIIT fans actually believe.
For example, another study focused on the same results but for steady-state cardio this time. Again, they measured the calories burned during and after a 45 minutes exercise and discovered a total average loss of around 700 calories (519 during the exercise and 190 after its conclusion).
A 2017 meta-analysis from a group of Australian researchers that studied the effect of both HIIT and steady-state cardio in fat loss, pooling the results of 28 different trials and data from a little less than one thousand people, came to an almost astonishing conclusion.
According to them, there is no evidence that HIIT is far superior to steady-state cardio when it comes to fat loss. They are both similarly effective, with HIIT being preferable only because it produces the same results in shorter training sessions.
So yes, HIIT will indeed induce fat loss – but so will steady-state cardio. HIIT will just do it in shorter training sessions, saving you time. This is indeed a major advantage, especially for people with a heavy daily schedule.
Just keep in mind that HIIT will prove effective only if coupled with a proper diet. An intense workout that burns a lot of calories usually leads to increased appetite – and, possibly, to a bigger calorie consumption than usual. In such a case, the person just re-takes the same (or even bigger) number of calories he or she has just burned.
This actually happens quite frequently among the less experienced and careful ones, since intense training provides a “moral” foothold for eating more.
Last but not least, keep also in mind that, according to certain studies, burning a great number of calories while exercising could make a person much less energetic in other of his or her daily activities.
Simply put, your body understands that you have already burned more calories than you usually do, so it reserves energy and refuses to burn more throughout the day.
While there is no proof that this is always the case, keep in mind that burning more calories during your training session does not automatically mean that you will burn more calories throughout the day.
The Verdict – Is HIIT an Effective Way to Lose Fat?
Yes, it is but is not so effective as it is often claimed and it surely is not that superior to steady-state cardio exercise.
Its main advantage is that it can deliver the same results with steady-state cardio in much shorter training sessions, thus saving you time.
Still, always remember that the surest way to fat loss is a proper diet.