3. Best Type of Cardio for Fat Loss
- Kate Philpott
- Apr 9, 2018
- 6 min read
HIYAAAAA! Want to know which type of cardio is the best for fat loss? Well this week’s blog post will look at the two very prevalent types of cardio; high intensity interval training (HIIT), which is a combination of very high intensity spurts and active rest intervals, and low intensity steady state (LISS), which is just one steady pace cardio session for a longer period of time (usually 30-60 minutes). Both types have their reasons for their popularity in terms of fat burning, so I’ll go into that in detail and then try to determine if one is ‘better’ than the other for burning that demon fat!
First things first, one of the main benefits of HIIT is the ‘afterburn effect’ or E.P.O.C. (Excess Post-exercise Oxygen Consumption), which basically means that it allows your body to burn more calories AFTER the cardio session is done, as opposed to only burning calories DURING the session itself. Now, I’m pretty interested in the extent of this afterburn effect. Laforgia, Withers & Gore (2006) suggested that 80 minutes of high intensity cardio (ahem.. that is more than I’ve probably ever done in any given 2 week period) only burned an extra 80 calories in the 7 hours post-exercise. Realistically, nobody in their right mind is going to be able for 80 minutes of high intensity cardio.. most people will do 20 minutes at MOST, so if these proportions are right, that would amount to an extra 20 calories being burned over the post-workout period.. and yes, that’s just as depressing to me as it is to you. What’s even worse is that Keating and colleagues (2017) suggest that overall, E.P.O.C. is unlikely to amount to any greater fat loss, when it comes to HIIT. So basically, HIIT and LISS (no evidence of E.P.O.C.) don’t even differ significantly on this front.
The next thing I’d like to consider is one of the main reasons for the popularity of LISS, and it’s that, when you’re working at a lower intensity, your body is using more fat for fuel, as opposed to using more glucose or glycogen (carbs). It is pretty well established in the research that generally, the highest rates of fat metabolism are found at exercise intensities of about 33% - 65% of max effort, which is relatively low to moderate (Romijn et al., 2000). However, while this is true, you still won’t burn more fat in general unless you’re in enough of a caloric deficit (see blog post 1 for more on this and fat loss). So, maybe LISS would have a slight edge in terms of the fact that more fat will be burned as fuel DURING the session, but in a 24-hour period, the calories (in AND out) matter so much more. In relation to calorie burn, it actually seems that both types of cardio will end up burning much the same amount of calories, when you average out the high intensity interval calories, active rest calories and E.P.O.C. of HIIT, and then the LISS calories in general (of course things like duration will play a role here too, so keep that in mind!). What’s interesting though is that with HIIT, you’re spending MUUUUCH less time actually performing the cardio, and that will mean you’re a hell of a lot less likely to eat into your muscle mass (the good stuff!). The more muscle mass, the better, due to 1. Body composition, i.e. a leaner, more toned look, and 2. Metabolism, because it takes more energy (in the form of calories) to maintain the muscle on your frame, than it does to maintain fat. On this topic, LISS is said to make you more likely to eat into your muscle mass. It reduces muscle glycogen (carb stores), which can impair weight training performance, thus impacting muscle building capacity (Nader, 2006). Basically, what this whole paragraph means is you want to hold onto as much muscle mass as possible, because it allows you to burn more calories throughout the day, and HIIT seems to have a slight edge when it comes to the maintenance of muscle mass. However, when you take recovery into account, this may change.
So, recovery - a pretty important aspect of this argument. Naturally, it is more difficult for the body to recover from something that causes it more stress. Of course in this case, that something is HIIT. Its higher intensity causes more stress to the body, thus making it more difficult to recover from. This kind of ties in with the last point, because if we’re not recovering properly from our sessions, our ability to lift weights may be impacted, which may in turn, impact muscle maintenance also. This can be hacked however, by keeping HIIT sessions apart from each other, keeping HIIT sessions apart from heavier/more intense lifting days (like leg day), and by doing your cardio AFTER your weights, because then you’ll likely refuel your body on several occasions (through meals and sleep) before your next weight training session. This is why nutrition and sleep are so important when it comes to recovery too, but that’s a whooooole other conversation in itself.
Next up – adherence. What good is a training program or type of cardio, if you’re never going to stick with it?! I’ll tell you what, it’s about as useful as a waterproof towel. Points in favour of consistency with HIIT; less boring (always looking forward to the next interval/rest), you can get it over and done with in just a few minutes. The negative side of HIIT however; it takes a lot more mental strength to really push yourself to the high intensity that’s required, and basically some may just find it ‘too hard’.. I know I’ve been there when I’ve just finished a tough weights session and the idea of doing HIIT makes me want to curl up in a ball and cry! Points in favour of LISS; you don’t have to try that hard or get into the right frame of mind to do it, you can just throw on Netflix or a podcast on your phone and go into another world. On the flip side, it can be very damn boring, just walking on the treadmill etc. for up to 60 minutes. Realistically, when it comes to adherence, you’ll just have to pick a type that suits you and your schedule best, and the one that you prefer, so that you know you’ll stick to it long-term, if you’re looking for real fat loss results. This part is very much based on your personality type, when it comes down to it.
Before I give my final thoughts, I’ll also add that a recent systematic review (Wewege et al., 2017) actually came to the conclusion that there is no significant difference in the effect of HIIT and LISS in terms of what it does for body composition, it’s just that HIIT takes a lot less time. In general when it comes to picking a cardio method to suit you for fat loss, it’s important to note that there are SO many other factors that play a role, such as calories in vs. calories out, NEAT (basically, calories you burn when you’re doing any activity that isn’t specifically exercise, e.g. amount of steps, fidgeting, etc.), cardio timing, nutrient timing, and so on. But, if we’re looking at cardio type alone – and we are – it’s probably best to fit both into your schedule, or at least to just fit in whatever type you are most likely to remain consistent with, as unsatisfying as that conclusion is!
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References
Keating, S. E., Johnson, N. A., Mielke, G. I. & Coombes, J. S. (2017). A systematic review and metaanalysis of interval training versus moderate-intensity continuous training on adiposity. Obesity Reviews, 18(8), 943-964.
LaForgia, J., Withers, R. T. & Gore, C. J. (2006). Effects of exercise intensity and duration on the Excess Post-exercise Oxygen Consumption. Journal of Sports Sciences, 24(12), 1247-1264.
Nader, G. A. (2006). Concurrent strength and endurance training: from molecules to man. Medicine and science in sport and exercise, 38(11), 1965-1970.
Romijn, J. A., Coyle, E. F., Sidossis, L. S., Rosenblatt, J. & Wolfe, R. R. (2000). Substrate metabolism during different exercise intensities in endurance-trained women. Journal of Applied Physiology, 88(5), 1707-1714.
Wewege, M., van den Berg, R., Ward, R. E. & Keech, A. (2017). The effects of high-intensity interval training versus moderate intensity continuous training on body composition in overweight and obese adults: a systematic review and meta-analysis. Etiology and Pathophysiology.
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