Does HIIT Create MORE Fat Loss?

It was the late ’90’s and my mind was being BLOOOOWN!!! I don’t say that lightly even though I know people love to use that statement about almost anything. The reason that I do find it appropriate to say something was mind blowing was due to the fact it would completely change how I train!

When I came across the information I am about to share with you I wasn’t new to training as I had already been working out for several years. Like so many people, I was using the strategy I just saw everyone else do. 

You do about an hour of strength training and 30-45 minutes of aerobic work (typically walking on a treadmill or the like). I never really questioned if this was best as it was just the same thing literally everyone in the gym did. 

Then I went to a continuing education seminar by a very new and who seemed to be rebellious strength coach named Charles Poliquin. During the seminar Charles dropped tons of research and put forth the ideas that high intensity interval training (HIIT) was far superior for fat loss than the more common moderate to low intensity but continuous aerobic training. 

The science seemed overwhelming and shocking. It was so big for me that during a college class when a professor asked, “we all agree that aerobic training is most important”, I was the only one that didn’t raise their hand. So, befuddled, he asked me my reasoning and even said that if I would write him a paper on why I believed so much in HIIT that he would change his mind. 

That next Monday, I handed him a 5 page paper with citations. I think he was surprised I did so and sadly I don’t really know if it actually changed his mind. Since then though, HIIT has become pretty much standard protocol. One of the big reasons that I fell in love with HIIT is it seemed like it could be the answer to why so many people workout, but do NOT get the fat loss results they want. 

Now, 30 years later of coaching has taught me no ONE thing is probably going to help our fat loss goals, but a collection of really good training and ideas can. Using HIIT with my clients though, I didn’t end up getting the impressive results that I thought would be the case. That has since caused me to go back over more current research and see if I have changed my mind about the effectiveness of HIIT. 

The Study That Inspired Me!

A 1994 study (PMID: 8028502) looked at comparing a 20-week endurance based training program or a 15-week HIIT program. What they found during the actual time of exercise, the endurance group burned almost TWICE as many calories, sounds like a slam dunk for endurance work right? 

The study actually found, “the HIIT program induced a more pronounced reduction in subcutaneous adiposity compared with the endurance training program.” This means HIIT was better at fat loss than the more aerobic based work. 

The researchers went on to say, “When corrected for the energy cost of training, the decrease in the sum of six subcutaneous skinfolds induced by the HIIT program was ninefold greater than by the ET program.” They concluded that HIIT was better for fat loss than longer more low intensity continuous training. 

Case shut right? Well….

More recent studies haven’t been as convincing as that 1994 study (PMID: 37927356, PMID: 37701124) showing very little to no difference between HIIT and moderate continuous exercise in fat loss. So, what gives?

It does appear that there could be many factors at play. The length and frequency of training time, the subjects fitness level, and even the type of exercise use could change the results. One study (you can read HERE) found that whole body interval training was more effective than jump rope interval training. So, it could be that we have to be careful about interpreting some of these results. 

One thing that the research seems to consistently show though is that when it comes to fat loss, HIIT is effective and could be MORE effective in reducing the amount of muscle loss during a reduced calorie diet (PMID: 37360303) and lowering cardiovascular risks ( PMID: 39076951). 

Don’t get me wrong, there is research that does show that HIIT produces greater fat loss but the research doesn’t seem to be consistent based on what I have shared. However, what IS repeated through all the literature is that at WORST HIIT produces the same bodyfat loss and cardiovascular benefits as more moderate and continuous forms. HOWEVER, the research says the absolute GREATER benefit of HIIT is that it does this in significantly less time. 

Since time can be such an obstacle for so many times, the research and my experience tells us that we should focus on more HIIT strategies in our training than more moderate and longer forms of training. I’m not saying you can’t do such things, but when time is a limiting factor and you want to optimize your time then HIIT is better.

Now, the key is HOW you perform HIIT which in our next article we will explain is often misunderstood and incorrectly performed by most people. 

Want to learn more? Don’t miss our upcoming FREE “Why Fitness Is Failing Fat Loss” Webinar October 7th HERE and save right now (only for limited time) 25% on our Fat Loss Masterclass with code “coach25” HERE

Some HIIT ideas for your training till next post!