I saw a post on Threads recently where someone asked, “Where is everyone getting this ‘Cardio is useless/overrated for fat loss’ from? I’m so confused.”

The comment section immediately erupted into war. People are incredibly passionate about their fitness beliefs, and seemingly, the more wrong they were, the more passionate they became. I was tempted to add my two cents, but the topic requires a lot more nuance than a two-sentence social media reply. Based on those comments, there is a massive misunderstanding out there, which makes it a great topic for a blog post.

The core question is this: Why do we hear more fitness professionals and influencers claim you don’t need cardio for fat loss, or even say it can be detrimental? Personally, I have been hearing this claim for years from popular bodybuilding channels. I follow online fitness voices closely, and truth be told, I’ve actually been seeing the tide turn back toward common sense lately. For years, doing cardio was heavily frowned upon in those circles.

I’m going to preface all of this by saying that I am a running coach and I love running. Everyone should be getting cardiovascular exercise as part of a well-rounded fitness routine.

The Cardio Bunny Era and Historical Muscle

I think this whole no-cardio trend began as an overcorrection to how the general public perceives cardio. A generation ago, it was common for women to adopt a "cardio bunny" routine. This persona revolved around dance classes, step classes, power walking, and jogging to lose weight. All cardio, all the time.

As a brief aside, I am watching Outlander for the first time, and I apologize in advance if this becomes my whole personality because I am obsessed. It reminded me how women in the 18th century never had to worry about lifting weights because their entire lives were spent doing manual labor. Even if you fast-forward to the 1940s, people were just more active. It wasn’t until modern life got easier that we had to intentionally strengthen to stay fit.

As modern life increased sedentary lifestyles, women gravitated toward cardio. Because of that, we experienced a generation or two who did everything they were told to stay fit, yet still ended up weak and frail in old age. Luckily, it does seem like the tide is turning and we see more and more women see the true value in lifting weights for longevity. Because of that, I think we will see fitter elderly people than ever before.

The Problem with an All-Cardio Approach

When cardio is the only exercise you do, you may lose weight, but you also lose muscle. This makes you smaller overall, but your body fat percentage may stay the same or even increase. This is a poor result. A person who weighs less but has less muscle is weaker, more susceptible to injury, and has a lower metabolism, which makes it harder to keep the weight off long-term.

I know about this firsthand. For the first few years of my fitness journey (20 or so years ago), I ran a lot, ate very little, and never touched a weight. My weight fluctuated constantly. I was sick or injured just as often as I was running, but I had it stuck in my head that running worked because I dropped thirty pounds in a few months.

What I didn’t understand back then was that a big part of those thirty pounds was muscle. Losing that muscle was the main reason I had such a hard time maintaining my fat loss. The struggle I faced for years could have been avoided had I taken a slower, more balanced approach that included strength training with my cardio.

The Bodybuilder Bias and the Interference Effect

The initial industry overcorrection was aimed at people like me. Bodybuilders knew muscle was the key to sustainable fat loss. So, the message became, "You don’t need cardio for fat loss,” which morphed into, “If you do cardio, you’ll lose muscle.”

There is also a distinct bodybuilder bias at play here. Many bodybuilders simply prefer the weight room. They stay lean without cardio, so they fail to see the perspective of those of us who genuinely enjoy it.

Secondly, there is the concept of the interference effect. The idea is that you cannot lift weights and do cardio at the same time because they create two opposing stimuli in your body. While this is true to an extreme extent, meaning you shouldn't train for a marathon and a strongman competition simultaneously, it doesn't mean you shouldn't do both at all.

It is much better to have a main priority and a supplement. For weightlifting goals, focus on muscle building and sprinkle in some cardio, which can actually help build your endurance for lifting. If you're a marathon runner, focus on running, but add a few strength days to maintain your muscle mass. The fear of losing muscle by doing 30 minutes of cardio a few times a week is unfounded. Unless we are talking about excessive mileage, cardio will only help your strength goals by improving your overall conditioning.

Why Cardio Progress Stalls For Long-Term Fat Loss

So, does cardio help with fat loss?

The answer is yes, but there is nuance to it. Fat loss depends on energy balance: how much you eat versus how much you burn in a day. When you take in less energy than you use, you lose weight. If you start running for thirty minutes a day, you will burn approximately 200 to 300 calories. Do that a few days a week, and that extra calorie burn can compound into meaningful weight loss.

The issue arises with continuous fat loss over time. The more weight we carry, the more calories we burn. In addition, the less efficient we are at an exercise, the more energy it requires. When we start out weighing more and moving inefficiently, we burn a lot of calories, which is why we see a drop in weight in the first four to eight weeks.

But if we are not actively preserving muscle, we lower our metabolism as our body sheds muscle as part of that weight loss.

Then, things slow down. When we weigh less, we naturally burn less. Combine that with less muscle and a slower metabolism. Also, the more cardio we do, the more efficient our bodies become. That is why it felt like a total sufferfest to run to the corner and back when you started, but now you call a five-mile run an easy day. Your body adapted, meaning you now burn fewer calories during that exact same workout.

To keep your initial burn rate, you either have to run farther or faster. After six months to a year, you would have to run farther or faster than what makes sense in a normal life just to continue losing weight. A lot of people realize at this point that it is easier not to eat an extra 500 calories a day than to try to burn them manually through cardio.

This is exactly why building muscle is so helpful. Like cardio, your body adapts to weightlifting. But unlike cardio, that adaptation enables you to get stronger and build more muscle over time through progressive overload.

Balancing the Heart and the Muscles

This is why cardio can be great for fat loss initially and is excellent for maintenance, but becomes less effective for increasing fat loss the better you get at it. Of course, this doesn't mean you shouldn’t do it. Cardio is vital for your health, mental health, and social connections. The American Heart Association recommends 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous activity per week, plus two strength sessions.

Ultimately, the best fitness programs feature a mix of strengthening for both the muscles and the heart.

When you build muscle, you boost your metabolism, which means you burn more calories just to exist. A lifetime of muscle-building activities is the most effective thing you can do for your health, longevity, and fat loss.

The great news is that you don’t have to choose a side in this internet war; the most fit and consistent people do a little of both. If you prefer cardio, lean into your strengths and build out a small strengthening program to balance your approach. If you prefer lifting, just a couple of moderate cardio days can help you reach your goals. If you enjoy both, adjusting your main focus every quarter or half a year can help maintain a strong, well-rounded fitness routine.

Never Miss A Blog Post!

Lea

There is no greater compliment than a referral!

Lea Genders is a board-certified health coach, personal trainer, and workplace wellness consultant based in Fort Worth, TX. She offers corporate wellness programs for employee health and productivity, as well as in-person and virtual training / coaching for individuals worldwide. Her blog shares expert guidance on strength training, running, and sustainable nutrition @fortworth_trainer