How Much Cardio is Too Much for Weight Loss?

“You have to do cardio” is a phrase that I as a personal trainer grit my teeth at whenever I hear people talking about losing weight. For as long as I can remember, “gurus,” magazines and the media have drilled into our heads that the key to weight loss is cardio, cardio and more cardio. Now, don’t get me wrong. Cardio is a wonderful thing for general health (especially heart health) and can be an amazing tool for burning fat…when done correctly. However, it is possible to get too much of a good thing and, if you overdo it, you could end up even fatter than when you started, studies show.


Out of all of the crazy stuff you see in the gym from powerlifting to boxing to agility and super-fit people lifting super-heavy weights, not only is cardio the least intimidating (especially if you are just starting a fitness journey), but there is research that supports the power cardio has on weight loss, especially in the form of high intensity interval training. There are numerous studies that show that this short, but intense exercise burns more body fat lower intensity, but longer exercise and is most effective at getting rid of stubborn body fat. Sounds great, huh?


However, before you start lacing up your sneakers for a 1-2-hour cardio session at the gym, keep in mind that overdoing it can not only stall your weight loss, but can be hazardous to your wellbeing. The general recommendation for cardio of any type is about 2-3 hours a week. However, this recommendation is usually for people that are sedentary and not doing much physical activity at all. Not for those that only need to lose about 10-20 pounds and are already active. So, by adding in another 2-3 hours whether that comes in the form of throwing in a cycling membership, signing up for a marathon or going to every cardio class they can fit in their schedule, isn’t necessarily going to help them lose more weight.


But why? If moderate cardio is effective, wouldn’t a lot of cardio be more effective? Unfortunately, the body doesn’t work that way. If you start overloading the body with exercise, whether it be too much of just cardio or too much of a combination of cardio and resistance training, you get a rise of the hormone cortisol which causes you to hold onto fat as a defense mechanism and this fat is usually stored in your belly. It also causes you to retain water and bloat which at this point people freak out and start to do more cardio to lose their belly, creating a vicious cycle.


If you really start pushing the limits, you’ll experience symptoms of overtraining. Basically, if you are having trouble sleeping or waking up, getting sick easily, are sore all of the time or feel more irritable than usual, then your body is breaking down from too much cardio. Another thing to note is that cardio does not preserve your muscle which, believe it or not, is just as important as losing fat. When we set out to lose weight, we want to lose fat, not muscle, right? However, excessive cardio causes us to break down both which is not only another cause of a rise in cortisol which stalls weight loss, but muscle loss also causes a drop in metabolism which will also hinder your weight loss in the long term.


The bottom line? More does not always mean better. You should cap your cardio at no more than 3-4 sessions a week and no longer than 20-25 minutes per session, no matter the intensity. Signing up for marathons and iron man competitions or spending hours on a treadmill is not going to drive weight loss, especially if you are eating away your calorie deficit or overdoing it with your workouts. In the end, my recommendation for a more effective, but healthy fat loss is weight training along with high intensity interval training to get the best of both worlds.  

To read much more about fitness and sports nutrition, visit Destini’s blog, The Athlete’s Dietitian.

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