November 29, 2021
Everyone wants to improve their body composition. Therefore, in the pursuit of weight loss, everyone wants to find the most efficient way possible. The quickest, most effective method of weight loss is the # 1 priority. In fact, some people will actually waste time researching which method is the best rather than actually training.
Two of the most common cardio training styles are HIIT (High-Intensity Interval Training) or MICT (Moderate Intensity Continuous Training). There seems to be a ton of debate on which is better to improve body comp with HIIT training usually taking the win. This begs the question, is it? Is this just gym bro talk, or is it backed by science?
Luckily for us, famed sports researcher Brad Schoenfeld and his team did an exhaustive systematic review and meta-analysis on all the studies they could find and found the answer. What they found might be surprising to some, but we can learn a lot from it.
As mentioned, this meta-analysis was conducted by Brad Schoenfeld and his team and was published in November of 2021. This makes it the most up-to-date analysis with the latest information there is. In total, the research team examined 54 studies that looked at the effects that interval training (HIIT) and steady-state (cardio like running or cycling) training had on body composition as well as other factors. In totality, the variables that were compared were:
We’ll take this one by one and go over the significant findings and points of interest.
When it came to which method was better for fat loss, the winner was....neither! Yes, that is correct. Both forms of training illicit similar reductions in fat mass loss, with any difference being insignificant.
Further, when the fat loss was examined as a whole, both methods of cardio training had a minimal effect on fat loss! In other words, neither method created significant amounts of fat loss. This may be surprising to some people due to the marketing tactics seen in the industry, but cardio training does not generate massive deficits in calories. To be clear, both are awesome, and even a little bit adds up over time; however, the most effective means of losing weight is your diet. Boring but true.
To be clear, technically you can burn thousands of calories a day doing cardio. However, we’re assuming you’re not doing a full Ironman triathlon. Therefore, keep in mind we are speaking about the typical lifter who just throws in some cardio to burn some extra calories.
One reason trainees usually point to HIIT-style training is for EPOC or excess post-exercise oxygen consumption. In a nutshell, this is the number of calories that you burn after your workout as your body tries to recover and bring your body’s physiological systems back to homeostasis. Since HIIT training is more intense, it’s believed to cause massive EPOC or’ extra calories,” as many proclaim. However, EPOC has been greatly exaggerated and is actually quite small. While studies do show that HIIT will cause greater EPOC, when compared to total calories, it is a modest amount at best.
So changes in fat mass were equivalent, but what about muscle preservation or even muscle gain? One claim that is often made is that HIIT is better at preserving muscle while steady-state can result in the breakdown of muscle. Or, some claims even suggest that cardio can build muscle if it’s intense enough. Therefore, the team compared which method is best to maintain muscle mass. What they found was really interesting.
For all intents and purposes, there was zero difference. However, somewhat surprising is that both groups saw an increase in muscle mass. While trivial, this dispels the myth that a steady-state will destroy your gains. To be specific, HIIT saw an increase of 0.11kg of fat-free mass, and MICT saw an increase of 0.07kg. Again, a very tiny amount, but that is a world of difference compared to “you’re going to destroy your muscle”.
There is some nuance involved. These sessions were not extreme, meaning they were not spending “hours on the treadmill,” which likely would cause some muscle loss. However, this retort that is often given to explain steady-state cardio does not mesh well with reality.
One drawback of HIIT is that many people will claim that it’s too intense for people to do long-term. When speaking of MICT, the claim of it being “too boring” is often used. Therefore, which style are you likely going to stick with?
When comparing the drop-out rates of these methods of training, you would be most likely to drop out of neither! Not only were the drop-out rates very similar for both groups, but they were also very low in general. Both groups completed about 90% of their sessions with a 13-17% drop-out rate. The conclusion is that both styles of training are appropriate, and it likely comes down to psychological preferences to determine which is right for you
Adverse effects were the last variable to be compared. Are you more likely to get injured with one method over the other? Interestingly enough, this was the only variable to get a different outcome than “everything’s the same”.
After reviewing injuries and health problems, the team discovered that the method most likely to cause injury was….inconclusive! This was primarily due to such a low number of studies that actually reported injuries in any meaningful way.
Their conclusion here was that researchers needed to start documenting injury rates.
Obviously HIIT and MICT are vastly different so there were something to consider as each had their own special benefit that may make them more appealing,
When it comes to HIIT, the workouts took less time. Therefore, you can the same amount of calories in less time. However, when considering the fact that you need to warm up really well for HIIT, the difference in time shortens. On average, you would probably be looking at a 10-15 minute difference. This might be useful for some trainees and should be taken into account
However, often times trainees underestimate HIIT training. HIIT is extremely intense which is why you can burn more calories in less time. This intensity not only requires more rest, many trainees simply don’t have the work capacity to perform HIIT effectively.
Considering MICT, it is much more accessible for the average trainee. It may take a little longer to perform but the recovery period is much shorter and doesn’t require such high levels of athleticism.
All of these variables should be taken into account when deciding what’s best for you.
As seen, this meta basically told us that neither method of cardio was superior for fat loss. Further, in terms of the general effectiveness for fat loss, neither are even that effective in the first place.
This may sound confusing at first due to all the marketing, but you need to consider the actual numbers. All kinds of ads speak about “torching fat” and losing an obnoxious amount of pounds in 30 days. However, training doesn’t work like that.
First, let’s take a logical look at how many calories you need to burn to lose fat. An approximation has you burning 3,500 calories to get rid of 1lb of fat. Now we take the average of calories burned in a typical cardio session. If you do something like a Tabata, you can expect to burn maybe 50 calories. With a more typical HIIT or 30min MICT session, you’re looking at 100-200 calories dependent on a lot of factors. To be conservative, we’ll give you 200 calories per session.
After doing the math, that means you need to perform 17.5 sessions to burn 1lb of fat through a typical cardio session. Assuming you’re not working out every day, that would take you almost 1 month to burn an entire pound of fat from cardio. Sure, you could do longer cardio sessions and burn more calories, but again, we’re assuming the average lifter who is just throwing in some cardio to burn extra calories.
Next, we can take a look at the recommended caloric deficit you need to be in to lose weight. Most nutritionists will recommend a very modest 300-500 caloric deficit daily. That is not a lot. To get this range, we need to remember that you will still burn calories from your weight training. We then add in your diet on top, and suddenly you don’t need to have a cardio session to burn 1,000 calories. There is this idea that you need to be able to burn “800 calories an hour,” which is ridiculous. In reality, if you burned 800 calories, you would need to actually eat an extra 300 calories to get to the recommended 500. The reason the recommended number is at 300-500 calories is because if you go higher, you increase the risk of breaking down muscle.
From these two numbers above, we find two things:
This is actually another “thing to consider,” but we think it deserves its own headline. There is the misguided belief that the purpose of cardio training is to burn fat. How many times have you heard “go do some cardio” when someone asks about burning calories? To be honest, even we say that as cardio is a great way to burn up some calories. That being said, we speak of it in its correct context as it’s excellent at contributing to extra calories. Compare this to suggesting that cardio is the most crucial aspect to improving your body comp.
While cardio is an excellent way to improve your caloric deficit, burning calories is not its sole purpose. In fact, burning calories isn’t even its primary purpose.
The purpose of cardio training is to improve your cardiovascular system. This includes improving fitness variables such as;
For example, I’m sure you have heard how great Tabata's are for burning calories in a short period of time. Creating a “fat furnace” was never the intended purpose of the original sports researcher, Izumi Tabata. Yes, Tabata workouts are named after the Japanese researcher who originally designed the protocol. His study in 1996 was actually intended to find a more effective protocol to train elite ice skaters. In fact, Tabata’s studies don’t even mention calories as their main purpose was to improve things like VO2max and work capacity. It wasn’t until small group training became more popular that gyms started using marketing gimmicks to showcase their “new” fat loss workout.
To be clear, cardio does burn calories, but that is a secondary benefit. You would be better off if you looked at training practices for their intended purpose. Here is how you should look at your training pillars:
The one thing that you need to understand when it comes to weight loss is that there is no magic bullet. No method of training exists that is so obviously superior that you’d have to be an idiot to not be doing it; which is often implied in some circles. Sometimes there seems to be this notion that trainers hold this weight loss secret that you can only discover if you buy their program.
Here’s the real secret. There are no secrets.
Yes, cardio can contribute to your overall body recomposition, but the calories burned from a single session are minuscule. This means it’s only effective if you are consistent with it over a long period of time. And that is the common theme in all of fitness. Nothing happens overnight. To be successful, you must be patient and disciplined.
All of this being considered, the best style of training is what’s suitable for your circumstances. Something that you enjoy and can push yourself. Other than that, you’ll just need to trust the process.
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