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The Truth about HIIT

The Truth about HIIT: Are You Getting the Benefits You Think?

High-intensity interval training (HIIT) has become a buzzword in the fitness world. Touted as a miracle workout for burning fat and increasing fitness levels, HIIT involves short, intense exercise and recovery periods. Yet, many people who think they’re doing HIIT are actually engaging in moderate-intensity interval training (MIIT). And here’s another surprise: the reputed fat-burning advantage of HIIT might not be as effective as marketed. 

The biggest attraction is the promise of HIIT (high-intensity interval training), which has been marketed to burn the most fat and improve cardio faster than all other exercise methods. Research has demonstrated that properly programmed and properly applied HIIT can improve cardiovascular fitness. However, the fat-burning promises are exaggerated and used to attract clients.

Let’s first take a look at what HIIT truly entails. High-intensity interval training is, as its name suggests, intense. HIIT involves short and very intense bursts (90% of maximum intensity) of exercise (5-20 seconds) with brief (30 to 90 seconds) intervals of rest in between. When done correctly, HIIT is very physically demanding and can be quite taxing on the body. By the end of the intervals, you should feel exhausted and unable to do more, which is why this training style can only last 7-15 minutes (not the 45-60 minute HIIT classes marketed to you). 

The problem? 99% of the time, people are not doing actual HIIT training as tested in scientific research. Real HIIT training means your heart is working at 90% of your max capacity for a very brief period. Bootcamp and HIIT classes do not get participants’ heart rates anywhere close to this. And if your class lasts 30-60 minutes, that cannot be HIIT training because you would literally be dead. So let’s be honest – you are doing moderate intensity interval training (MIIT) (where your heart rate is getting to more than likely upwards of 70%), which is still valuable and beneficial to overall fitness and health, as long as your form is good and you are not hurting yourself. (I also note that you do not need to do MIIT daily to get in shape.)

Let’s debunk the myth about HIIT being the ultimate fat-burning solution. A common belief is that HIIT burns more fat because it produces a higher post-exercise oxygen consumption (EPOC), in which the body continues to burn calories at an accelerated rate even after the workout. While this is true to an extent, the difference in calorie burn between HIIT and other types of exercise is smaller than one might think. Remember, this is based on actually doing actual HIIT sessions, which you are more than likely not doing. 

Research shows that while true HIIT may lead to a slightly higher EPOC, the overall caloric expenditure is heavily influenced by the duration of the exercise. In other words, a longer, moderate-intensity workout can burn as many, if not more, calories than a shorter, high-intensity one. Additionally, your body can only maintain high-intensity activity for a limited time, which means HIIT workouts are often shorter, potentially leading to less overall caloric burn. 

Bottom line:  the caloric expenditure of any exercise is NOT what you think, and the marketing is always exaggerated to reel you in. It is false and misleading advertising. 

First and foremost, fat loss starts in the kitchen. Fat loss will happen when nutrition is addressed, and for that, you need to seek the advice of a registered dietitian, not a weekend certified nutrition ‘coach’ who only knows how to starve you and create disordered eating. The process of burning fat is multifaceted and involves more than just crushing fake HIIT workouts. 

Check out our blog that breaks down fat loss:  “Exercise Won’t Give You a 6-Pack”.


Most people need to learn how to move correctly before attempting to do anything moderate to high-intensity. The complete mismatch between low readiness for movement and high workout intensity is why and where injuries happen. Unfortunately, most people that do boot camp style HIIT either:

1) don’t stick with it long enough to see any results and/or

2) get hurt, so they don’t stick with it. 

These common outcomes can completely deter well-meaning people from exercise because HIIT or boot camp classes are gruelling, not enjoyable, and now comes with a fear of injury. However, the goals of improved endurance, strength, and cardiovascular health can all be improved without risking injury and crushing your soul, but you likely won’t hear the boot camp or HIIT instructor tell you that.

When programmed and coached correctly, moderate-intensity circuit training has a place! Moderate-intensity exercise is safer and more sustainable in the long run, allowing for consistent progress and reduced injury risk. MIIT is where you work 60-70% of your maximum heart rate during active intervals. While this is still beneficial and can improve cardiovascular health and conditioning, it is notably less intense than an actual HIIT workout. However, the confusion lies in the broad interpretation of “intense.”

For someone not accustomed to high levels of physical activity, a moderate workout might feel very intense, thus leading to a misunderstanding about the true nature of their workout. MIIT is still a great way to work on conditioning and endurance. But let’s move past the marketing hype that it is a fitness panacea and past the belief that almost puking after every workout is the ticket to being in shape. Exercise should build you up, keep you injury-free, and not consistently crush you and prevent you from enjoying its benefits in life.

While true HIIT can be an effective workout strategy for some, it’s essential to understand what it truly involves and not be swayed by the hype. Many who think they’re doing HIIT are probably doing MIIT, which is an excellent form of exercise. And when it comes to burning fat or fat loss, there’s no shortcut or magic formula; it starts in the kitchen (nutrition).

A well-rounded workout regimen and a healthy, balanced diet are essential. Finding a workout routine, you enjoy and can sustain will always be the most effective route to your fitness goals.

We offer a Metabolic Conditioning Class.  This moderate to high-intensity interval training class uses structured and foundational whole-body exercises with specific rest periods to MAXIMIZE fitness fun while crushing some cardiovascular gains and increasing your ability to tolerate more work. This heart-pumping conditioning class is manageable for everyone, regardless of fitness level. YOU decide on the intensity and pace.  Want to push to 80 percent?  CRUSH IT.  Only feeling 70%?  CRUSH THAT. 

This class is perfect for those who want to reap the benefits of interval training but are too intimidated by random burpee boot camp workouts that only focus on making you tired, rather than making you better. Our approach allows for sustainable progress, making it a safer and more long-term exercise strategy.

Whether you’re a beginner or a seasoned fitness enthusiast, this class suits all fitness levels. The trainer will provide modifications and progressions, allowing you to tailor the workout to your individual needs and abilities.

Sign Up Here:  https://clients.mindbodyonline.com/classic/ws?studioid=35966

Try your First Class FREE using promo code:  firstclassfree

Shara Vigeant, BA, NSCA-CPT, CFSC