5 Myths about Cardio and Fat Loss

A woman performing cardio exercise on her bike.
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The topic of cardiopulmonary (heart and lung) fitness is much maligned and often misunderstood. We’ve all known a few “cardio junkies” in our day – gluttons for punishment who are constantly doing workouts that us mere mortals wouldn’t touch with a 100 foot pole. However, the fact remains that using exercise to maintain heart and lung function mitigates our risks of some of the most serious diseases and dysfunctions that affect Americans (not the least of which is heart disease, the leading cause of death in the United States).

When it comes to exercise, most of us have a “favorite”. That is to say that while some people love pumping iron and the thought of walking a mile makes them want to puke, others live for the next marathon while turning their nose up at the thought of lifting a dumbbell in their spare time.

The fact is, if we want the physical and emotional health benefits that being in shape provides, we need to be doing both. Let’s look at the physical activity guidelines for Americans where cardio is concerned:

  • 150 minutes per week of moderate-intensity physical activity (read: walking, light biking, dancing, light swimming), OR
  • 75 minutes per week of vigorous-intensity physical activity (read: running, hiking, HIIT, playing sports)

Let’s take a look at some of the most common myths about cardio that are pervasive in our society:

Myth #1: Effective cardio is time consuming

Where cardio is concerned, many of us feel pressure to complete an hour of cardio a few times per week. With our current fitness culture, it’s easy to have an “all or nothing” mentality about exercise. We think that in order to be “fit”, we need to go to the gym six days per week or train like a triathlete. However, as we saw when investigating the Physical Activity Guidelines for Americans, two resistance training sessions per week and some cardiovascular training is all we really need.

The Truth: Cardio can be done in as little as 5-10 minutes

As we saw in our micro-workouts series, effective training sessions can be completed in as little as 3-5 minutes. The same goes for cardiovascular training. Note that walking is one of the most underrated forms of exercise – if we spent 10 minutes walking in the morning and evening each day, we’d have accounted for 140 minutes of moderate-intensity exercise per week. Just this minor lifestyle adjustment would make a world of difference in our mental and physical health, as well as our waistline (as long as it’s paired with a good diet). In fact, daily 10-minute walks are one of the primary fat loss supplementation strategies used by professionals!

Recent research has even suggested that walking sessions as short as five minutes can be effective for health and fat loss. Hopefully, that’s a far cry from the sweat-fest you had in mind. A few ideas:

  • Take a 5-10 minute walk each morning before you shower.
  • When you get a work call, take the call outside and walk for the first 15 minutes of the call.
  • Take a 5-10 minute walk each evening after you get home from work or after dinner.

Yes, short duration cardio is effective. In fact, if the goal is to hit 150 minutes per week, you’d be hard pressed NOT to make that happen if you’re using this approach.

Myth #2: High intensity training (HIIT) is better than jogging or walking

While we think there’s nothing particularly wrong with doing HIIT training, there is a dedicated cadre of fitness experts who bill high intensity interval training as a silver bullet for fat loss. They cite the “afterburn effect”, wherein a person becomes a “fat burning machine” and receives extra calorie burning benefits for many hours after the session is finished. This afterburn effect is known as excess post-exercise oxygen consumption, or EPOC.

The Truth: There’s basically no difference

The reality is that low- or moderate-intensity cardio typically takes more time and will burn more calories during the session. In contrast, high intensity cardio typically takes less time and burns less calories during the session but more calories after the session. In the real world, this means there’s almost no practical difference between the two and you should just pick whichever form of cardio you like more.

While the EPOC effect is a real phenomenon supported by the research, its benefits have been wildly overblown:

  • One 2006 study found that in subjects who performed high intensity interval training for 80 minutes straight, the EPOC effect lasted about seven hours and resulted in around 80 extra calories burned.
  • A 2017 systematic review of 31 studies concluded that There were no differences between HIIT/SIT and moderate-intensity cardio training (MICT) for any body fat outcome. Analyses comparing MICT with HIIT/SIT protocols of lower time commitment and/or energy expenditure tended to favor MICT for total body fat reduction.”

Since high intensity training is extremely taxing, it’s reasonable to assume most of us won’t be doing HIIT for 80 minutes straight. This would further mitigate the benefits of the “afterburn” effect. Contrast this with basic forms of cardio like jogging, walking, or riding a bike, which can easily be sustained for 30-60 minutes at a time.

Make no mistake, high intensity intervals such as sprints are a fantastic (and time efficient) form of cardio, but as far as total calories burned, it has no real benefit over low intensity cardio like walking or jogging.

Myth #3: Cardio burns through muscle

There is a common sentiment among iron-heads who don’t want to become “skinny runners” by doing too much cardio. However, this doesn’t just apply to bodybuilders. We know that maintaining strength and muscle mass is important in preventing injury, pain, falls, and dysfunction as we age. If doing cardio “eats” through muscle, isn’t that doing the opposite of what we want?

The Truth: Doing cardio incorrectly burns muscle

This one is less of a myth as it is an oversimplification. These people will often cite the documented “interference effect” between the AMPK enzyme produced to replenish energy stores from cardio sessions and the enzyme mTOR which signals muscle growth after resistance training. In English, what that means is that the two adaptations are fundamentally at odds with one another.

However, it’s important not to throw the baby out with the bathwater on this one: this 2017 study showed that when a steady state cardio session was completed 24 hours after a resistance training session, normal adaptations were seen from both sessions. More recent research has shown that separating the two workouts by as little as six hours can achieve the same effect.

This has led many professionals to recommend a simple tweak: perform your cardio in the morning, and resistance training in the evening, or simply perform them on separate days. Much to the chagrin of cardio-haters, this approach seems to neatly sidestep the “interference effect”.

Myth #4: Fasted cardio is best for fat loss

There is a school of thought that when cardio is done first thing in the morning (on an empty stomach), the body will utilize fat and carbohydrate stores for energy, rather than the calories ingested in the pre-workout meal.

The Truth: It doesn’t make a difference

While there is nothing wrong with doing fasted cardio, or cardio first thing in the morning, studies have shown that it really doesn’t make a difference. For example, this 2014 study compared two groups of female volunteers who were randomly assigned to perform “fasted” cardio or “fed” cardio three days per week. All twenty volunteers received nutritional counseling and diet plans to induce a calorie deficit. After six weeks, both groups had lost similar amounts of fat mass with no significant difference between groups.

Myth #5: Gardening [or insert other general “moving around” activity here] is enough

There are two common categories of people who feel that their regular lifestyle negates the need for exercise:

  • Group 1: Those who engage in regular “moving around” activities (such as gardening, or walking to get the mail every day), and
  • Group 2: Those who say that their active job (such as construction) is enough physical activity.

The Truth: You still need to exercise

The first point is simple enough to make. In general, exercise should be somewhat challenging and provide measurable progress over time. I don’t know anyone who measures the intensity, duration, and progress of their gardening … do you? The problem with this argument is that (1.) the duration of the activity is usually grossly insufficient and (2.) there’s no real way to measure whether or not it’s working.

The second group’s point requires a little more insight. Interestingly enough, there is research on this topic. While at face value, it seems perfectly logical to conclude that an active job would provide the same benefits of getting regular exercise, the research suggests otherwise. This study found that “occupational physical activity (OPA) does not confer the cardiovascular health benefits that leisure time physical activity does.” The reason for this is not entirely known yet, but we do know that physical activity at work and physical activity in your spare time do not provide the same benefits.

In Conclusion

We hope you have taken something from the contents of this post. Did you believe any of the myths above? If so, it’s a great time to make tweaks to your routine in order to achieve better results! If you haven’t started a routine, check our post on how much exercise we should be getting to get started.

As always, if you have any questions, shoot us a call or contact us. We would love to hear from you!

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