Last updated:

25 July 2023

Which training style is better for fat loss – Insanity or HIIT? They both have merits, but today I must crown a champion!


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7 min read

Which training style is better for fat loss – Insanity or HIIT?

They both have merits, but today I must crown a champion!

Website subscriber Candice emailed in last week to ask about this comparison, check out her message below.

“Hey Russ,

Every time I see my friend she tells me how great Insanity is, and says I’m missing out on results by only going to the gym. Is that true?”

– Candice
insanity vs hiit

Before we get stuck into the research, I’d like to give Insanity props for those late night infomercials.

Man, they’ve got that s**t down to a “T” (no pun intended).

If you’re sat in your underwear at 3 A.M. holding a scrumpled up chocolate wrapper and an overbearing feeling of regret (we’ve all been there), you’re primed and ready for the moment these guys explode onto your TV screen and tell you they can make everything awesome again for three easy payments of $99.99.

High fives… burpees… cheering for the next exercise to start… it has it all!

It’s no wonder it caught fire, but how effective is Insanity when we take away all the glossy packaging and hype? Is it better than HIIT for fat loss?

Let’s get stuck in.


In order to compare Insanity vs HIIT we must first understand the key differences between them.

After all, many people believe Insanity is HIIT.

It’s not.

There are slight differences between these two training styles, and one in particular is crucial in determining the winner.

hiit vs insanity


HIIT is a very old training style.

It shot to popularity after being used by sprint coaches prepping their athletes for the 1992 Olympic Games, and one of the best studies on the benefits of HIIT dates back to 1994. (1)

It is based around one concept – heart rate manipulation.

The goal is to perform short bursts of maximum effort followed by a slightly longer recovery phase. Rinse and repeat this for the duration of your workout. It’s as simple as that.

However, what’s happening inside your body is crazy.

Those short bursts of explosiveness will jack your heart rate to sub-maximal levels, and the recovery phase should be long enough to allow your heart rate to recover before the next burst takes place. This high/low approach forces our body to burn through carbohydrates for fuel, meaning it has more in common with a weight training workout than a cardio workout.

This creates a phenomenon called EPOC (excess post-exercise oxygen consumption), otherwise known as ‘The Afterburn Effect’, which puts the body into a state of accelerated fat burning for up to 14 hours. (2)

The 1994 study I touched upon earlier showed participants who performed high intensity interval training burned almost 9x more calories (and more fat) than those performing regular aerobic cardio, despite the HIIT group’s shorted workouts.

interval training vs max interval training


If you’ve ever done Insanity you’ll already know it isn’t structured the same way. Insanity is based on something they constantly refer to as Max Interval Training.

But here’s where things get wierd…

There is no such thing as ‘Max Interval Training’.

They’ve merely repackaged an old training style known as HISS (high intensity steady state), and made it sound way cooler. As a training style HISS is like the bigger, stronger brother of aerobic cardio.

It’s based on much longer intervals with very brief recovery periods to allow the trainee to catch their breath before the next round begins. This actually works in the opposite way to HIIT, as it flips the work/rest ratio to favor more activity and less recovery.

Now you know the key difference, which one is better?

insanity workout review
Action movie star Adam Baroni stops by for an outdoor sprint session based on the principles you see above.


HIIT wins and it’s not even close.

I’m not saying Insanity is ineffective. Providing you stay consistent and work hard, you can get great results with it. I’ve used it myself in the past.

But the reason HIIT wins comes down to one crucuial factor; adaptability.

We know the body will adapt to any training program over time, and in order to see continuous results we must find a way to increase the difficulty. So while the first 2 months of any decent program will unlock pretty good results, beyond that we need a plan which takes it up a notch. (3)

This is where programs like Insanity get it wrong.

“The definition of Insanity is doing the same thing over and over, and expecting different results.”

Rita Mae Brown

With Insanity your only option is to start over and try training even harder while hoping not to get injured in the process.

Eventually, the risk of injury overtakes the potential reward of results due to the sheer amount of high impact exercises (burpees, jump lunges, power squats, etc). Knee issues are easy to come by and ACL tears (caused by twisting awkwardly while trying to land a rep at high speed) are common among Insanity users.

insanity vs hiit

Meanwhile, HIIT allows for much safer progressions to be made.

When the time comes to make things harder, you simply restruture your recovery phases to match your new ability. In the past you might’ve needed 3 minutes to recover from an all-out 30 second blast, but now you can recover in 2 minutes. So the work is not getting harder, which keeps you clear of injuries, but the recovery is getting better.

Make sense?

Also, as HIIT is purely time-based, as opposed to following a preset list of exercises, this unlocks another potentially huge factor in helping you stay consistent in the long-term; variety.

If we take a look what’s happening inside your body during training, we’ll see another reason to go with HIIT.

We have 3 types of muscle fibers:

  • Type 1 muscle fibers (endurance).
  • Type 2a muscle fibers (hybrid).
  • Type 2b muscle fibers (explosive strength).

Those type 2a muscle fibers can either be transformed into additional type 1 muscle fibers or additional type 2b muscle fibers depending on the type of training we do on a regular basis, and can make ALL THE DIFFERENCE with your physique.

Regardless of its intensity level, steady state cardio tells our body to create more type 1 (endurance) muscle fibers in order to handle all the endurance work we are doing.

HIIT and weight training will tell your body to build more type 2b muscle fibers. It’s also got greater muscle sparing capacity. (4)

is insanity hiit
Team GB Olympic athlete Amanda Lightfoot slams a 40kg bag during a HIIT session at the gym.

So there you have it.

The long-term adaptations, ability to safely apply progressive overload, and the growing body of academic research to verify it’s effectiveness are the reasons why my male and female clients base their cardio routines around HIIT.

Occasionally they’ll run a program like Insanity to provide a fresh stimulus. I believe that’s the best way to use it.

I hope you’ve enjoyed this breakdown of Insanity vs HIIT for fat loss results.

Jump on my free email list for more tips (be careful not to tear your ACL!), and get workouts by whacking the button below.

Who Is Russ Howe PTI?


Russ has been a personal trainer in the UK since 2002, and provided both training advice and full programs on this website since 2011.

His work has been featured in Men’s Fitness magazine, and the content on this website led to him being voted one of the world’s top 50 fat loss coaches by HuffPost.

Russ spends his time coaching men and women inside the legendary Powerhouse Gym, South Shields, and writing training tips for the 114,301 members of his popular free training e-mail (join it below).


  1. Trembalay, A., et al. Impact Of Exercise Intensity On Body Fatness And Skeletal Muscle Metabolism. Metabolism. (1994)
  2. Knab, A. M., et al. A 45 Minute Vigorous Exercise Bout Increases Metabolic Rate For 14 Hours. Med Sci Sports Exerc. (2011)
  3. Mangine, G. T., et al. The effect of training volume and intensity on improvements in muscular strength and size in resistance-trained men. Physiol Rep. (2015)
  4. Wilson, J. M., et al. Concurrent Training: A Meta Analysis Examining Interference Of Aerobic And Resistance Exercise. J Str Cond Res. (2011)

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