Show Menu


Are HIIT and Tabata really worth the effort?

High intensity interval training (HIIT) has gained popularity in recent decades.

It refers to any form of activity that alternates high intensity activity with periods of lower to moderate intensity activity (eg, 20-second sprint intervals with 60 seconds of walking, jogging or even complete rest.

By contrast, aerobic or steady state training (eg, jogging) is where a reasonably steady intensity is maintained for an extended period (say, 20 minutes or more).

For some, HIIT is revered as the single best way to burn calories in a time efficient manner.

With numerous variations under the broad umbrella of HIIT methods (e.g. Tabata, a short interval training protocol), HIIT can indeed be a time-efficient way to improve conditioning and overall fitness.

Perhaps because it also shares a couple of metabolic traits with resistance training (short bursts of intense effort followed by a period of rest, and an ‘afterburn’ effect), it’s often sold as a way to burn fat with minimal loss of lean mass.

But actually, HIIT does not always translate to an improvement in body composition or fat-loss efforts.

Fat Loss
For a given amount of work, you will burn more calories with HIIT compared to aerobic or steady state training (because you are doing that work in a shorter period of time). There is also a greater ‘afterburn’ effect, meaning you will continue to burn more calories after you’ve finished the exercise.

In most instances, however, the amount of energy burned afterwards, known as excess post-exercise energy expenditure (EPEE) and related to post-exercise oxygen consumption (EPOC), is considerably overplayed.

When comparing a 20-minute high intensity interval session versus a 30-minute continuous running session at a lower intensity, the interval session resulted in 57 more calories burned. This figure included both the calories burned during the exercise session as well as those burned afterwards (EPEE) and concluded that the major contribution to weight loss from both steady-state jogging and HIIT was from the energy expended during the actual exercise. The afterburn effect was “of negligible physiological significance as far as weight loss is concerned.”

It’s well worth noting that the researchers in this study made sure that the total amount of work done was equal between the two sessions.

The main benefit of interval training (HIIT) for fat loss is not, then, the calories burned per se but rather the time efficiency. For those with busy lifestyles, HIIT may be a preferable method to expend more calories in less time but a true HIIT session (repeated all-out sprints for 30 seconds-plus) is not for everyone.

For what it’s worth, anecdotally Bodyscan has seen a decrease over the years in the number of DEXA scan customers reporting HIIT as part of their exercise regime. We can also report that, again anecdotally, practitioners of HIIT did not achieve DEXA scan results suggesting they retained more muscle than those who didn’t; though this is far from a scientific study. If you want to maintain or build muscle while losing fat (body recomposition), you’d do well to follow the simple advice here.

The problem with regular HIIT is that it is taxing on the body and may interfere with strength and muscle gain by causing too much fatigue. Higher intensity means higher recovery and thus may prevent effective, progressive resistance training over time.

Given the fact that steady state training involves far less recovery, a reduction in injury risk and a lower requirement for cardiovascular fitness compared to HIIT, it may be a more feasible approach for beginners or people who are overweight or obese. Similarly, for those looking to optimise muscle building, it may be prudent to steer clear of regular engagement in true HIIT sessions.

If you are considering HIIT as part of your exercise programme you would do well to get an accurate and precise measure of your current body composition by way of a DEXA body scan before you start. Combined with a calorie deficit (which the Bodyscan team will calculate for you and which will, itself, take into account your HIIT schedule), the high-intensity sessions will contribute to your total fat-loss that we’ll monitor with subsequent Progress scans. But as explained above, don’t expect HIIT to be a magic button. As your DEXA technician will explain, fat-loss is achieved primarily through calorie restriction (limiting what you eat and drink), not exercise.

One aspect of fat-loss where HIIT does seem to be superior to steady-state cardio is in the reduction of visceral fat (internal fat around the organs), linked with type-2 diabetes, stroke and other obesity-related diseases. As we explain in this DEXA information video, visceral fat is metabolically active and responds directly to vigorous exercise, just as muscle responds directly to the stimulus of being subjected to resistance (weights in the gym). Subcutaneous fat (the fat you can pinch) does not respond to exercise in the same way; exercise only contributes to subcutaneous fat reduction by virtue of the calorie (energy) deficit caused as a result of the exercise. Again, as we will explain with our DEXA calculator, that calorie deficit is achieved much more effectively by a calorie-restricted diet.

Both HIIT and steady state training are effective methods for increasing overall fitness and can be used as a fat-loss tool to complement your nutrition. In the context of fat loss, adherence is the primary predictor of success, so choose a training protocol that you know you can stick to rather than worry about what type of ‘afterburn’ it might give you.

Kevin Garde
Nutritionist and Bodyscan Consultant

How much is a DEXA scan in the UK?

Bodyscan’s DEXA prices are very affordable. A Baseline scan with in-depth, personalised face-to-face consultation is £169, and you can make significant savings by buying a pre-paid DEXA package upfront. All DEXA costs are on our pricing page, both single scans and packages. Take a look and make your booking now!