Three Cardio Myths Sabotaging Your Fat Loss (And How to Fix It)

Cardio is great for your health, and I recommend almost everyone include some in their fitness program.

But, there are some persistent myths out there that can really sabotage your efforts. 

These myths can cause all sorts of problems, from struggling to see tone or definition, to mental burnout, to muscle loss, and even continuous cycles of weight regain. 

If you have ever added cardio in, but still felt soft or ‘skinny-fat’ despite putting in hard work, it feels frustrating. 

You’re not alone, and it doesn’t mean you are broken.

Many of these habits are encouraged all over the place in the fitness world. They sound logical, but the problem is, they don’t actually hold up in practice. 

So let's clear them up, and replace them with a smarter approach. This is the same balanced approach we use with our personal training clients.

1. You Can Eat Back the Calories You Burn From Cardio

This one applies to all exercise, but is especially pertinent with cardio. Apps or wearables often exacerbate this one by adding in calories burned to your calorie intake allotment for the day. Please turn that setting off if you are tracking food intake; it will do more harm than good!

According to research, us humans tend to overestimate the calories we burn when doing cardio or other exercise. Often by about 2-3x as much as we actually burned. Wearables are not much better, having estimates with as low as 30% accuracy, and at best around 80% depending on the type of exercise. 

We’re also quite bad at estimating our caloric intake, typically under-estimating it by around 20-50%. 

Yikes…pretty easy to see why giving yourself even just what seems like a little extra treat to reward a hard workout can backfire quickly. 

But, there is more. When we do a hard cardio session or another type of workout, our body tries to make up for it by reducing unconscious movements we do like fidgeting, pacing, etc. That type of exercise is called Non-Exercise Activity Thermogenesis (NEAT), and when it goes down we burn even fewer calories. (British Journal of Nutrition, 2018)

This is a big reason why people say,

“I added cardio but the scale didn’t move.”

What works better, is to use exercise primarily for health, fitness, and muscle retention. Not solely for a calorie burn, and definitely not with the intent to eat more food or make up for past cheat meals (or cheat days…been there). You can also help counteract the natural drop in NEAT by using those wearables to hit a daily step target. That is one thing that they are great for. 

Speaking of step tracking, that brings us to the next myth. 

2. You Need 10,000 Steps Per Day

The 10,000 step count target came from marketing, not science. It was used as a benchmark to advertise the very first step trackers, and it just kind of stuck. No surprise, it’s catchy and it’s a challenge, so it feels like it’s doing something. 

But do you really need that many?

The research does show that 10,000 is better than 2000. But, health benefits actually start to level off around 7000 steps. (The Lancet Public Health, 2025) So past that the returns you get are diminished.  That said, going past 7000 steps is not bad, and can be a great way to burn extra fat without a whole lot of extra stress or to keep NEAT from dropping during fat loss phases. 

So, if you are hitting 7k regularly, you're getting the majority of the health benefit already. More can help with fat loss, but it's optional, not required. 

3. Cardio Is Better For Fat Loss Than Strength Training

This one is a bit nuanced, because you will burn more calories (and fat) during a typical cardio workout than you will doing a typical strength training workout.

According to research from Harvard Health, stationary biking at a moderate pace burned around 250-300 calories over 30 minutes. Biking at a vigorous pace burned 315 to 450 calories over that same time frame. Moderate strength training burned just 90 to 126 calories in 30 minutes, and even vigorous strength training topped out at 250 calories in 30 minutes. (Harvard Health Publishing)

So, it’s true that you’ll burn more calories from cardio than you will from strength training, when comparing a single bout of exercise. 

But, calories burned in a given workout is not the only consideration when it comes to fat loss.

Here’s why it’s not that simple: 

Studies looking at weight lost using just cardio show that around ¼ to ½ of the weight lost comes from muscle. I don’t know about you, but losing half the weight I lose from muscle does not sound like a good prospect. 

Losing muscle has a myriad of negative effects, including: 

• Being weaker

• Lacking tone or definition despite a low body-fat percentage

• Lowering your metabolic rate, which makes it harder to maintain weight loss

• Increasing your body-fat percentage

The last two are particularly detrimental for those that are trying to lose fat and keep it off. Increasing your body fat means you’ll have to work harder and lose even more total fat to get to your goal body fat percentage. Lowering your metabolism again makes it tougher to lose the fat and even more difficult to keep it off. This is why cardio alone for weight loss very often leads to regain. (Journal of Clinical Endocrinology & Metabolism, 2021)

A Smarter Approach to Cardio

Instead of using only cardio for fat loss just because it burns more calories, you should combine strength training and cardio to get the best effect. Strength training will preserve or even build muscle while you drop fat, making you look lean and defined, bumping up your metabolism, and making losing fat and keeping it off much easier. (BMJ Open Sport & Exercise Medicine, 2025)

Cardio is great for heart health, extra calorie burn, and, if you’re one of the rare people who love it, enjoyment (yes, runners, talking about you).

If any of this sounds familiar, take it as clarity, not criticism. You do not need to chase cardio calorie burns or punish yourself to get results. A smart balance of strength, cardio, and sustainable habits is what will build a body that looks and feels lean and strong. Focus on consistency and let cardio enhance your program, not dominate it.  

Want help applying a smart balance of strength, cardio, and sustainable habits so you can look and feel your best?

Click here to book your initial personal training session in Austin or online from anywhere.

Sources

Kahan, S., & Manson, J. E. (2021). Long-term weight loss strategies for obesity. The Journal of Clinical Endocrinology & Metabolism, 106(7), 1854–1866. https://doi.org/10.1210/clinem/dgab091 

Binmahfoz, A., Dighriri, A., Gray, C., & Gray, S. R. (2025). Effect of resistance exercise on body composition, muscle strength and cardiometabolic health during dietary weight loss in people living with overweight or obesity: A systematic review and meta-analysis. BMJ Open Sport & Exercise Medicine, 11, e002363. https://doi.org/10.1136/bmjsem-2024-002363 

Harvard Health Publishing. (n.d.). Calories burned in 30 minutes for people of three different weights. Harvard Health. https://www.health.harvard.edu/diet-and-weight-loss/calories-burned-in-30-minutes-for-people-of-three-different-weights

Ding, D., et al. (2025). Daily steps and health outcomes in adults: A systematic review and dose-response meta-analysis. The Lancet Public Health. https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667%2825%2900164-1/fulltext

Silva, A. M., Júdice, P. B., Carraça, E. V., King, N., Teixeira, P. J., & Sardinha, L. B. (2018). What is the effect of diet and/or exercise interventions on behavioural compensation in non-exercise physical activity and related energy expenditure of free-living adults? A systematic review. British Journal of Nutrition, 119(11), 1327–1345. https://doi.org/10.1017/S000711451800096X

Lopez, P., Taaffe, D. R., Galvão, D. A., Newton, R. U., Nonemacher, E. R., Wendt, V. M., Bassanesi, R. N., Turella, D. J. P., & Rech, A. (2022). Resistance training effectiveness on body composition and body weight outcomes in individuals with overweight and obesity across the lifespan: A systematic review and meta-analysis. Obesity Reviews, 23(5), e13428. https://doi.org/10.1111/obr.13428