High intensity interval training (HIIT), Low intensity steady state ( LISS), or moderate intensity for fat loss? This is a question I get asked many times and I’m here to give you my honest and professional advice based on many years as a PT and having worked with literally thousands of clients. I’ve also attempted to link into as much research on this confusing subject as I can.
Let’s start by defining the different types of ‘cardio.’
LISS (Low-Intensity Steady State) — Cardio done at around 50% of your maximum heart rate, at a steady pace, generally for extended periods of time. A strong power-walk is an example and it’s not unusual for LISS sessions to last an hour or more.
HIIT (High-Intensity Interval Training) — Cardio done in intervals of maximum intensity, with low-intensity rest periods in between. Generally sprinting flat out for 20/30 seconds with 45/60 second rest periods, then repeating for several rounds. HIIT sessions can last as little as a couple of minutes, and rarely exceed 10-20 minutes.
Moderate intensity — Cardio which is somewhere between LISS and HIIT in terms of intensity and length. Jogging or cycling at a strenuous but manageable pace are examples of this. Moderate intensity cardio sessions will often last around half an hour.
WHAT THE RESEARCH SAYS?
In truth, the findings on cardio and fat loss are mixed. Some studies reveal interval training as more effective than moderate-intensity cardio, while some suggest both forms are equally effective.
A 2008 study published in the International Journal of Obesity found that, compared to a steady-state cardio group, the research group performing HIIT lost significantly more fat, whilst also reducing insulin resistance at the same time. However, other research has found HIIT and moderate intensity cardio to result in a similar amount of overall fat loss.
Not exactly conclusive or helpful on the research front but encouraging for me as a trainer as it’s helped me form my own conclusions through my experience and quite frankly there are far too many variables to define which cardio rules! For example; on a given ‘cardio’ day, hormone imbalances, burnout, lack of sleep, lack of motivation, are all factors to take into consideration when deciding whether to HIIT or LISS it.
From a scientific standpoint, whilst you burn a higher proportion of fat when you exercise at a lower intensity (approximately 60% of calories burned come from fat versus 35% during high-intensity exercise), you’ll actually burn more total fat from interval training.
MY OWN FINDINGS BASED ON MY EXPERIENCE AS A PT
When it comes to weight loss, there are many ways to do it, and whilst the bottom line does equate to calories in vs calories out, there are other factors which influence this equation as mentioned above. Hence it annoys me slightly when PT’s continually bash on with the calorie deficit mantra. I strongly believe that strength training is key to long term weight loss (along with cardio) since muscle is so tightly coupled to metabolism.
HIGH INTENSITY INTERVAL TRAINING
I personally love HIIT and have witnessed favourable changes in my own body and many of my clients, with regular HIIT sessions (on average twice a week).
https://www.jennirivett-blog.com/home/sprintone8
The positives on HIIT;
Time efficient and bang for your buck: Short on time? HIIT is easily the most time efficient.
Can burn more calories in a shorter period of time.
Boosts metabolism for up to 24 hours post exercise.
It produces in abundance HGH (Human Growth Hormone), which is both a lean and youth hormone and significantly declines with age.
However, HIIT is not for everyone and is – as the name suggests – fairly intense and unless your’e feeling rested, fit and energetic I do not recommend it; it can’t be done daily. A huge part of getting fit and keeping up an effective exercise routine is to prevent over-training so that you stay healthy, motivated, and continue to make incremental progress towards your goals over time.
Hormonal disruption can literally wipe you out and going too hard during your workouts can trigger the stress hormone cortisol, especially if you’re already stressed. This sends your body into fight-or-flight mode, which slows some key functions in the body, including your metabolism and immune system. This can cause more frequent bouts of illness and encourage your body to store fat. Needless to say, you’re not likely to stay in good health and continue making progress in the gym if you over train yourself with too much HIIT, or any form of exercise.
MODERATE AND LOW-INTENSITY CARDIO
As lower intensity forms of cardio are less stressful on the body, they’re less likely to cause you to over train when used as the backbone of your cardio regimen. Benefits for LISS include, among other things, reduced blood pressure, heart rate, cholesterol, and severity of depression.
In terms of weight loss, accumulating 10 000 steps (or more) a day will have a significant impact on weight loss, and I can certainly vouch for this! After a move from South Africa to London and a massive increase in my walking, the weight fell off me. The only drawback to LISS is that it’s time consuming and does not pose enough of a cardio challenge done on it’s own.
Moderate intensity exercise such as running is really great for releasing endorphins and the ‘feel-good’ factor. It’s also a little quicker on the time factor, but not always easy for everyone to perform.
IN SUMMARY
There’s little doubt exercise is great for helping people lose their weight And interestingly enough, the most successful weight-loss maintainers — those who lose weight and keep it off — credit this to consistently sticking to a regular exercise regime as a key component to keeping the weight off.
Whilst all types of cardio are great forms of exercise, there are different benefits you can reap from doing different types of cardio. The best type of cardio is the one best suited to your goals and needs. So whether your’re aiming to lose fat, looking for a low-impact exercise, or looking to get a quick workout in, there are ways in which you can tailor your workout to meet your needs and get optimal results.
Your best bet is to perform a combination of moderate-intensity and high-intensity cardio — as long as you enjoy both forms of cardio.
