“I’m feeling a like I’ve gained a little weight.”
“Oh, just do a ton of cardio to burn it off.”
This conversation has been had in gym locker rooms everywhere ten bazillion times over. For some reason, we have it stuck in our collective mind that strength training is great for toning and giving our bodies shape, but to really lose weight the only answer is more cardio.
And while you might know better—after all, we’ve all seen the effects of strength and resistance training programs like Kayla Itsines’ BBG and The Body Boss Method—your workout routine might unwittingly contain too much cardio for your own good.
Doing too much cardiovascular exercise causes hormonal imbalances
More isn’t always better, especially when it comes to low-to-moderate intensity exercise like jogging or cycling. Just because you might technically burn more calories in a 90-minute spin class compared to an hour long Pilates class doesn’t mean you’ll actually lose more weight. That’s because there’s a lot more involved than “calories in, calories out” when it comes to burning fat and building muscle.
A study published in the European Journal of Applied Physiology found that participants who engaged in longer sessions of low-intensity cardio had suppressed levels of T3, the important hormone that’s responsible for burning fat, compared to their short duration, high-intensity counterparts.
Long, sustained bouts of cardio cause muscle loss
Decades ago, some marketing exec had the brilliant idea to add a “Fat Burning Zone” option on workout machines. The myth of this magical fat-busting workout zone perpetuates, and it’s likely one of the factors that contribute to our obsession with medium intensity cardio exercise.
Surprisingly, completing a long session of low-to-medium intensity cardio actually causes muscle loss—instead of using fat as fuel to burn calories, your body will work through it’s limited glucose stores and then more on to using lean muscle as fuel. Eventually, you’ll be left with more fat than muscles … which is why it feels like even when you do two back-to-back Soulcycle classes, you still don’t feel like you can see muscle definition.
Overexercising can cause an increase in cortisol production
Finally, exercising too intensely too often has its own set of repercussions—in the short term, not taking the time to rest means that your body never fully recovers, and you’ll see fewer results from your workout. More seriously, if you overwork your body for long stretches at a time, you can exhaust and deplete the adrenal system. One side effect of adrenal fatigue is the inability to lose belly fat, even if you’re eating well and exercising daily. Why? Because your body is stressed it releases and overproduces the hormone cortisol, which makes it difficult to burn excess fat.
So how do you know if you’re doing too much cardio? Unless you’re training for a specific race or event, you need just three days of cardiovascular exercise per week, in addition to strength and resistance training. That being said, everyone is different—your body might prefer just one to two days of cardio instead! If you really feel like your body has plateaued and you’re not seeing results from your workouts, try cutting back on the cardio just a little. You might be pleased with how your body reacts!