New Study: HIIT is Not What it Claims to Be


Dear Reader;

Are you shocked by my title?  Me too!

In the fitness community lately, there is an undertone of sorts, villainizing (is that a word?) cardio.  I’ve heard it over and over again, the opinion that cardio is a waste of time and that strength training is best for losing weight.  I wrote an entire blog post about this, last year,  TRUTH About Exercising to Lose Weight.

But then there are combos that give you strength training AND cardio at once, in 20-minutes.  What could be better than that?  These are built for the people who need to save time!  Things like HIIT are claiming to be the end all to fitness goals, accomplished in less than half the time, each week.

Well, there was a small but significantly interesting study, that was published this month, about HIIT.

The actual publicized results are here at PUBFACTS.


If you’d like translation, I can help you with that.

I’m a pretty big fitness / nutrition researching dork who takes pleasure in reading all these findings that are published.  It’s where I get most of the content for my blog (studies).  I don’t base things on hunches or what I read in another blog.  Science is pretty hard to argue with and it’s what I think should guide all of us.  Not gym goer opinions.

Not that I don’t state my hunches or opinions, I just don’t state them as fact.

Furthermore, when I hear of new studies out and proving something I’ve said wrong, I correct it.

When you read the study, know that android fat is referring to those of us who have what we call the “apple” shape.  We carry our fat in the upper body with an emphasis on thicker in the middle.  Unlike the “pear” shape, who are thicker through the butt and hips.

The study had three groups HIIT group (HIIT), cardio group (CONT) and the placebo group (PLA).  The placebo group didn’t do anything; they didn’t change their habits – they are the control group.

The group consisted of 38 inactive and overweight adults.

Visceral fat is the fat that is located in our abdomen, underneath our organs.  THIS is the dangerous worrisome fat that is linked to increased risk of cardiovascular disease and events (like heart attacks).

Trunk Fat vs. Visceral Fat = trunk fat is the entire upper body with a high concentration of abdomen fat; visceral fat is only the abdomen fat, but more specifically, it’s the fat UNDER the organs only visible with scans, and visceral fat does not include chest, back, neck like the trunk does.

The study took place over 12-weeks.

The Results in a nutshell:

Trunk Fat

– 1.6% for CONT

+1% for HIIT

-.4% for PLA

This means the trunk fat decreased for those only performing cardiovascular exercises.  Trunk fat INCREASED for those performing HIIT.  The placebo group actually lost trunk fat, but who knows why.  We all naturally lose/gain weight in a set amount of time.  Our bodies regulate.

Android Fat

– 1.3% for CONT

+.7% for HIIT

-.8% for PLA

This means the android fat decreased for those only performing cardiovascular exercises.  Android fat INCREASED for those performing HIIT.  The placebo group actually lost android fat, again, like the trunk fat study, who knows why.

What it ACTUALLY Means

This study was pretty small.  I want to see these results duplicated in a much larger group of individuals where their information about their ages, body size, body type, background, etc… is made available.  Also, I’d be interested in a study that used a group who did both cardio and strength training, but on different days, not combined like the HIIT workouts.

Does this prove definitively that HIIT is not what it claims to be?  No, but it sure does make me less likely to run out there and subscribe to the claims, especially since they GAINED fat around the middle!!

The official statement of this study is that HIIT claims efficient strategy for comparable results, but this study DOES NOT CONFER.

So, in a nutshell, HIIT should be regarded as a hypothetical, but not likely, truth.  Until further study comes along proving HIIT’s claims, do something that is proven to work for your goals.  Good old-fashioned eating well, performing cardio and strength training.   We all wanted to believe you could combine cardio and strength training (an hour and a half worth) into a 20 minute workout, but sorry, it’s just not backed by science.

Like this poster’s claim; don’t believe everything you read:



There Are Good Uses for HIIT

HIIT isn’t all bad.  If you throw it into your routine occasionally, I bet it would help you with your goals, in combination with other proven strategies.  The body needs to be confused.  That is scientifically backed.  Cross-training (doing different kinds of cardio) is how to avoid boredom and keep the body guessing too.  HIIT may be one form of cardio in your arsenal.

I’ve also read a very small research study out there that states HIIT was showing to increase testosterone levels.  I was actually researching this for a client with low testosterone levels.  She is female.   So, if you’re low in testosterone, maybe HIIT is for you.  BUT this study makes me tread lightly for those of us (both male and female) who have sufficient testosterone…


4 thoughts on “New Study: HIIT is Not What it Claims to Be

  1. I think they leave out A LOT OF INFORMATION. My comments at the end included. But I’d also like to know what body types were involved in the study; how many were apple vs. pear. Bodies react differently. I think they used untrained because most people looking to burn fat in 20-minutes are the general public who are out of shape, looking to lose weight. I don’t think they would recommend anyone to do HIIT outside of their lab. They were probably doing it in a very controlled environment. Plus, really fit people don’t have the fat burning goal, typically. Their goals are strength or definition. So I can see why they used that particular population. HIIT is relative, so their “all out effort” is much less than someone who is fit, too. Even fit people are not advised to do HIIT on their own. I wouldn’t recommend HIIT to someone right out of the gate either, but after 2-3 weeks of working with them, I would have considered using it as a means to boost fat loss. I will probably take this off the table for use with my clients though, after reading this study.

  2. Interesting. To me I think the big factor here is that they used untrained overweight subjects. Untrained overweight subjects are not generally cut out for HIIT. The HIIT group probably was unable to perform the way it’s necessary to get the benefits from it (not to mention it’s dangerous for them.) I would never suggest HIIT for a beginner. So I’d definitely agree with the study that it’s not effective for untrained overweight individuals. They also make no mention of diet, did the subjects eat whatever they wanted? Was it the same? What were the macro ratios? Etc.

    However I’m just like you that I like to see all the data out there and I’m not attached to any idea. But I’ve seen a lot of evidence that in trained individuals the EPOC and fat burn is higher in HIIT than steady state to think it’s not true. At the same time, all forms have their benefits and none should be considered king IMO. I just want to clarify I’m not disagreeing with anything, just chatting about it! :) Thanks for the info! Fascinating stuff, I love science!

    If interested, btw, here is a research analysis done with LOADS of research if you have time. One thing they did say, which is what this study did do, was “The effects of HIIE on subcutaneous and abdominal fat loss are promising but more studies using overweight individuals need to be carried out.” Perhaps it just further shows that HIIT is better for trained and steady state is better untrained. Who knows, but I’m sure there will be more research done!

    • Meant to hit reply on the last comment and instead, posted an entire new comment…

      I totally agree about the diet too. They left out a lot! I’ve always had my doubts about the HIIT claims though. I think anything that is too good to be true, typically is. Especially in this industry.

      • Yeah studies often leave out a lot and make me wonder. Of nothing every really “proves” anything, just gives us more to debate about. :)

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