A few years back, Jim Karas, personal trainer, dropped a bomb on the health and fitness world with his formal denouncement of “cardio” for weight loss. While promoting his new book, Lose the Cardio, Lose the Fat, on Good Morning America, Karas challenged the conventional wisdom that cardio training is the key solution to weight loss.
Rather than provide a clear solution backed by logic, evidence, and experience, Karas instead contributed to the murkiness that clouds most people’s understanding of effective weight loss.
I agree with the general premise of Karas’ claim. However, I have two big problems with how he delivered and defended his message. Understanding these two issues will take you one step closer to learning about truly effective weight loss strategies, and allow you to better understand whether the information you hear is the real deal, or just more garbage.
First, Karas makes a claim that will certainly create a buzz, but fails to come clean with defining the term at the center of the debate, “cardio”. And this is a big deal. You see, most people associate cardio with using the treadmill, bike, elliptical trainer, or a step class for 40-60 minutes at a steady pace.
But this doesn’t make any sense! Cardio literally refers to the heart. Muscles need blood, and high amounts of it, to transport oxygen and other nutrients essential for work. And the heart is responsible for pumping the blood. So an increased heart rate means that you are working the heart, right?
Do you think your heart has any idea if you are on a bike, swinging a sledgehammer, or performing squats? All it knows is that it needs to pump to supply working muscles with blood. So resistance training is cardio. Take your pulse after 3 sets of squats alternating with 3 sets of chin-ups. That ticker is really kicking! And some resistance training can be more intense than riding an elliptical trainer.
So when Dr Weil, an exercise physiologist, and Karas are debating about the importance of cardio for weight loss, the more logical argument would have been to first determine what they mean by “cardio”. The real debate is not about how effective cardio is, but what role does resistance training (high intensity, long rest, or lower intensity, low rest) play versus low intensity, long duration aerobic training (what the term cardio implies). The answer to this is clear: resistance training is more effective for fat loss than this form of “cardio” training.
Unfortunately, Karas does not make this distinction, probably because it would ruin his marketing hook.
Here’s the second big problem: Dr Weil stated that Karas had no evidence to support his claim that cardio was ineffective for fat loss. Karas merely resorted to his success with clients, and his own personal experience. The problem here is that there IS strong evidence showing that prolonged, low intensity “cardio” is less effective than weight training and/or high intensity interval training (HIIT). And there is even some evidence to suggest that prolonged low intensity “cardio” is not effective for weight loss. Many studies depict that not only are HIIT and weight training more effective, but they also require less time and frequency! Less work, better results! One major caveat: it is much more difficult work, and it’s more complex. There’s always a catch!
So why did this issue have to get so complicated? Well, many exercise physiologists don’t make their living based on the results they provide for clients. And Mr. Karas, well he likely gets results for many, but he is more of a marketing expert within the trenches of experience in the fitness industry, and no formal education pertaining to health or fitness. Professionals need both academia and real world experience to qualify as experts. Absolutes (no carbs, no fat, not cardio, etc) are rarely true, and there are always circumstances that dictate why one option may be appropriate for some, and not for others. A professional comes clean about these distinctions, rather than hide them to sell a more digestible message.