The Worst Cardio Mistakes Most People Make For Fat Loss (Avoid These)

No one wants to be inadvertently making mistakes that compromise results or worse still, cause injury. This is certainly true when it comes to cardio training. Since I’m a big fan of cardio traini...

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No one wants to be inadvertently making mistakes that compromise results or worse still, cause injury. This is certainly true when it comes to cardio training.

Since I’m a big fan of cardio training that’s done in the right context and performed in the right way, I think it’s worthwhile to lay out the five most common cardio mistakes that people make when trying to lose fat.

Contrary to what some gym bros might tell you, cardio work has some serious benefits worth tapping into. Cardiorespiratory Fitness, which is basically your body’s ability to give your muscles oxygen when they need it, is a major predictor of death from all causes (All-Cause Mortality), including Cardiovascular Disease.

In a 2009 meta-analysis, when it came to both all-cause mortality, coronary heart disease, and cardiovascular disease, nearly every study favored high cardio fitness over low cardio fitness. Aside from the obvious health benefits, having better cardio can also help with your training goals by improving overall work capacity and recovery between sets.

To really grasp this, simply think about how much harder three sets of eight reps on the squat feel when your cardio is lacking. If you’ve been skipping cardio, it’ll likely feel as if you will need to rest forever between those sets. In fact, you may even struggle to get all the volume in. However, when your cardio is on point, you can get all that work done much more efficiently.

It’s also worth mentioning that Physical Activity is an important factor for long-term weight maintenance.

Research shows that individuals who are more active tend to be more successful in keeping the weight off after a period of dieting.

Despite these more obvious upsides of cardio training, there's still a lot of misinformation circulating around the gyms, locker rooms, and social media. So, let’s dig into some of the biggest mistakes that I see people make, and then lay out some practical recommendations.

Mistake #1

Thinking that cardio is as effective for fat loss as diet is

Even though being physically active is uncontroversially important for health, cardio isn’t required for fat loss. This is because, at the most fundamental level, fat loss ultimately comes down to the difference between the number of calories that you consume and the number of calories that you expend.

Sadly, the number of calories you expend in a typical cardio session is pretty depressing.

To illustrate, consider that if you weigh 170 pounds (77 kilograms), it would take you roughly three hours of brisk walking to burn a thousand calories, but you can eat a thousand calories in less than a minute if you really tried.

Actually, fitness model Steve Cook showed this disparity well. In response to a 10,000-calorie food challenge, he tried to burn 10,000 calories the next day. Despite being one of the most physically fit guys in our industry, and despite his greatest effort, he still couldn’t do it. Exhausted and frustrated, he ended up getting to just over 7,000 calories burned.

As you can see from this example, it’s definitely much easier to eat calories than it is to burn calories. If that isn’t disappointing enough, further insight reveals an even grimmer reality.

New research shows that when you do the math, weight loss from cardio still only amounts to 20-50 percent of the weight loss you’d expect to see from the number of calories burned alone.

To illustrate, let’s say that you burned 2,500 calories over the course of a week through cardio (approximately five hours of brisk walking on the treadmill) and did nothing with your diet. Based on the math, you’d expect to lose about 0.7 pounds, but would only actually lose 0.14 to 0.36 pounds. That’s a mere quarter to a half of what you’d expect!

There are 2 possible reasons for this.

Compensatory Overeating - Basically, when people are told to just do cardio but not to do anything with their diet, they’ll often subconsciously start eating more.
Metabolic Adaptation - Your body is “smart” and when it notices that you’re burning more calories through cardio, it tries to preserve more energy by burning less calories through the other metabolic components. It isn’t perfectly clear exactly which component of metabolism is most responsible for this, but some evidence points toward it being due to reductions in NEAT or Non-Exercise Activity Thermogenesis (your regular daily activities that aren’t formal cardio stuff, including fidgeting, moving around at your desk, bringing in the groceries, and so on).

It seems then, that as you increase the number of calories burned through exercise, your body subconsciously starts moving around less. This results in fewer calories being burned through NEAT, and thereby less weight loss than what you’d expect.

To be clear, even though you could theoretically completely offset your cardio through compensatory overeating, that’s not very likely to happen if you’re actually making an honest effort to regulate your diet as well. You’ll certainly never see so much compensatory NEAT reduction that you start gaining weight as a result of cardio.

My simple point is that the more and more you rely on cardio for fat loss, the more and more diminishing its returns become as your body compensates and adapts.

I’m putting this mistake at the No. 1 spot, not because I think cardio isn’t effective, but rather to help prevent people from setting unrealistic expectations about what cardio can do on its own. In addition, from a fat loss standpoint, I think cardio should be used like a supplemental tool that assists your diet, rather than the engine of fat loss itself.

Mistake #2

Poorly timing cardio around weight training

One of the most important things to consider with cardio is whether or not it’s likely to impair your weight training performance. You may see this referred to in the literature as the dreaded Interference Effect. This interference effect is the reason why there are so many memes that cardio is killing your gains.

While I do think the idea has been overblown by bodybuilders who just don’t like doing cardio, there’s still some truth to it. There is a well-established conflict between the aerobic endurance pathway and the muscle-building pathway.

It’s reassuring to know that there clearly are smart things you can do to help squash that interference. Perhaps the simplest way is just by doing your weight training first.

A 5 to 10-minute warm-up on the stairmaster, or whatever machine you like, has been shown to improve subsequent weight training performance. However, doing a formal cardio session that takes longer than 10 minutes or so should be done either after weights or at a separate time altogether.

A 2017 systematic review and meta-analysis on concurrent training pulled the results of 13 studies and found that placing cardio immediately before weights resulted in significantly worse improvement in one rep max strength and that strength training is compromised for at least 6 to 8 hours following endurance training.

Obviously, the extent of that compromise depends on how long and how intense the endurance training is. Yet, these authors suggest that separating endurance and resistance exercise by 24 hours, when realistic, could be a useful strategy to optimize concurrent training adaptations and avoid acute interference.

I should also say that the interference effect is more of a concern for advanced trainees than it is for beginners.

A brand-new 2021 meta-analysis found that concurrent cardio and weight training had no impact on strength for untrained and moderately trained individuals but did significantly impair strength in more well-trained individuals.

The bottom line is that if you really want to knock out your cardio and weight in the same session for convenience, you should do your cardio last. Furthermore, the more advanced you get in your training, it wouldn’t be a bad idea to create more separation between your cardio and weight training. This could mean doing them on separate days or doing one in the morning and the other in the evening.

Mistake #3

Falling into the high-intensity trap

As we dig into this third mistake, I want to make certain that we are all on the same page with two important terms. You likely know that coaches tend to break up cardio into two categories: LISS and HIIT

LISS - Low-Intensity Steady State or MISS - Moderate Intensity Steady State

This is when you do cardio at a steady pace, like walking on an incline treadmill or Stairmaster.

HIIT - High-Intensity Interval Training

This is when you go all out at a high exertion for 20-30 seconds or so, and then switch to a light pace for 2-3 minutes. The pattern gets repeated for five or six intervals.

Many people seem to think that HIIT is more effective at burning fat because of the so-called Caloric Afterburn Effect (When more calories are burned in the hours following exercise - Excess Post-exercise Oxygen Consumption)

While the afterburn effect certainly is real in that you will indeed burn ‘extra’ calories after high-intensity exercise and after low-intensity exercise, I still think its practical relevance for fat loss has been overblown.

One study showed that even after 80 minutes of high-intensity cardio at 80 percent max heart rate, only an additional 80 calories were burned from the afterburn effect.

A more recent systematic review stated that the afterburn effect is unlikely to account for any apparent extra fat loss potential.

However, even if we put the afterburn idea aside, HIIT still has the appeal of being more time efficient, since you can burn the same number of calories in as much as 40 percent of the time commitment.

Another upside of HIIT is that some people do find it to be less boring, which seems to be a perfectly sensible reason to use it.

Although the time efficiency and enjoyability of HIIT can count as upsides, the biggest downsides are that it does tend to interfere with weight training more and it takes longer to recover from.

You could also argue that HIIT is more redundant since weight training and HIIT are quite physiologically similar. With typical moderate to high rep weight training, you go at a high exertion for 20-30 seconds, rest for two or three minutes, go at a high exertion again for another 20-30 seconds, and repeat.

Considering this similarity, some experts have said that you already get most of the benefits of HIIT through weight training. I’m not sure I completely agree with that. In my experience, although HIIT does increase heart rate more and present a greater cardiovascular challenge than typical weight training, it’s similar enough to knock the unique value of HIIT down a few notches.

In summary, if you’re going to use HIIT, use it more sparingly. In my decade of coaching experience, because of its higher recovery demand, I rarely prescribe HIIT sessions more than once or twice a week, and often only if the client prefers it.

Mistake #4

Doing too much cardio

Even if we do everything else right, in terms of timing and intensity, it’s still possible to do too much cardio. To give us some idea on this, let’s take a look at the results of this NSCA Meta-Analysis on the interference effect.

When it came to cardio frequency, although the correlation wasn’t that strong, researchers noticed a drop-off in hypertrophy around the three to four-day-per-week zone. It seems then, that while this is a trend to be aware of, I don’t think you need worry that your muscle is going to melt away if you do cardio more than three to four times a week. Note how the graph also shows a negative correlation between hypertrophy strength and power and the length of endurance exercise per day. Additionally, in the second graph, we can see that the higher you get above 30 minutes per day the more interference occurs.

In gaining perspective on this effect, we shouldn’t look at this frequency and volume data in a vacuum. After all, taking your dog for a walk isn't comparable to running suicide sprints. What I recommend for cardio will be highly individual and depend on the type of cardio you’re doing.

Mistake #5

Banking on fasted cardio for extra fat loss

Since fasted cardio has become such a hot topic in recent years, allow me to get right to the point. The bottom line with fasted cardio is that just because you will burn more fat during the session itself, doesn’t mean you’ll lose more fat overall.

In fact, this 2011 study found that when you burn more fat during a cardio session, you burn less fat over the next 24 hours.

This systematic review found that performing exercise in a fasted state did not influence weight loss or changes in lean and fat mass, and that a meaningful caloric deficit is more important than exercising in fasted or fed states.

Recently, a review paper from Escalante and Barakat looked at the research on fasted cardio in the context of competitive Physique Athletes.

While the authors once again acknowledge that there is no conclusive evidence on the superiority of fasted cardio, they do point out that research on physique competitors hasn’t been performed. Thereby, they leave open the question whether or not it might be beneficial in the final stages of fat loss.

They also suggest that protein-enhanced cardio, where one consumes about 25 grams of protein beforehand, might have a slight edge in some advanced cases.

Still, I think that for the most part, simply do your cardio at a time when you can stick to it the best, whether that means you’re doing it fasted or fed.

Although this is not an exhaustive list of the mistakes one can make while participating in cardio training, it does represent the most common and salient, especially for weight trainers.

As we conclude, let's quickly pull all these mistakes together with some PRACTICAL RECOMMENDATIONS:

Volume

Include cardio as needed to keep up with your desired pace of fat loss.

Generally, losing 0.5 to 1 percent of your body weight per week is a good range. If you’re able to do this with weight training and diet alone, then you don’t need to do any cardio.

With that noted, I almost always suggest at least some cardio because it will allow you to keep calories slightly higher, improve weight training work capacity (as long as it’s not excessive), and set up good activity habits for weight maintenance after the diet is over.

Intensity

Keep HIIT between 1-2 sessions per week, lasting about 15 to 30 minutes per session, and simply add in low-intensity cardio as needed.

Of course, this recommendation will depend largely on your occupation and lifestyle outside the gym. Folks who work a chair-bound desk job might only burn 300 calories per day, while those working a more strenuous job in agriculture could burn up to 2,300 calories per day through NEAT alone.

So, depending on the client, I may prescribe anything from 0 to 5 low-intensity steady-state sessions per week, lasting 20 to 40 minutes per session, while monitoring their strength and recovery in the gym.

Because of lower interference, for most, I generally favor lower-impact cardio, such as walking, cycling, swimming, and the elliptical over higher cardio, like running on pavement. But, if the client simply prefers the higher impact options more, that certainly can be balanced by considering the other interference variables that we talked about.

If you’d so enjoy, a summed-up video of this blog is also available on my YouTube channel.