Updated: Mar 25, 2022
If you want to lose fat, stop doing cardio. Yes, you read that correctly - traditional cardio can actually cause you to keep body fat. I recently listened to one of the best explanations of exercise physiology metabolism ever. Ever since I have been in fitness for over 20 years, so that is saying a lot.
Dr. Doug McGuff, MD, is an emergency room physician, personal trainer, and extremely well-read in exercise science and nutrition. In discussing his recent book, Body by Science, with Dr. Joseph Mercola, DO, he summarized what I have been teaching clients for years; your body is designed primarily for anaerobic exercise, NOT aerobic. Aerobic energy system work actually is a result of doing proper anaerobic work. If this article is getting too technical just stick with me, it will gel in a minute.
When you do traditional cardio you are mostly burning fat for fuel. Most of us plenty of fat stores, even those that are considered lean. Your body is not forced to tap into muscle energy stores called glycogen (stored glucose).
Why is this a problem? Because over time our bodies become conditioned to burning fat for fuel during exercise and therefore dietary calories from fats, carbohydrates, and even proteins, are shuttled to fat cells, in part, to help keep an energy reserve.
Your body is a very smart machine; if you tell it to burn fat for fuel it will want to conserve its body fat stores to ensure there is plenty of fat for when you do your cardio. Worse, when you ignore muscle glycogen a very nasty condition develops called insulin resistance. It's beyond the scope of this article to tackle, but suffice to say it precedes almost all cases of obesity, heart disease, and diabetes.
Further, "cardio" works your small, weak muscles, called slow fatiguing or type I fibers. They are designed to work all day burning fat for fuel. This conditions your body to reduce the larger, more powerful, muscle fibers, type II or fasting fatiguing, as they are seen as merely losing muscle mass, and slowing your metabolism all the while your body is guarding your fat stores like the Swiss Guard protects the Vatican.
This is why most long-distance runners have little muscle mass, are not as lean as they appear (averaging over 20 percent body fat), and do not have better morality than the average person. I am not stating that running or the elliptical is unhealthy. But how you perform the activity is what makes it healthy or not.
The long, moderate to slow cardio is the exact opposite of how your body was designed. Take a look at kids on a playground. Do they jog laps when they play tag? No. They dart back and forth in bursts of energy, then rest when they get pooped. Then they start the cycle over again.
They have the metabolism of an elite athlete! Do you ever see animals in their natural environment slowly jogging on a daily basis? No. They casually move when they migrate and feed but at the slightest sign of danger, they sprint for several hundred yards, then rest. They see if the danger is still present, then sprint and rest again.
Whether predatory or prey, just about all animals act in this way. We are merely another species in the animal kingdom. It's time to start acting like it.
The next time you do cardio, all you need is 12 to 15 minutes. Choose any modality (type) of movement you like: track sprints, hill runs, bike sprints, elliptical sprints, circuit training with weights (but the weight must be moderately heavy) chase your kid(s) around the yard...chase a greased pig...chase your spouse or the neighborhood cat that keeps getting into your trash bin at night. Just pick something you like and perform it at maximum effort for 30 to 60 seconds, take a minute or 2 breaks, repeat for 12 to 1 minutes. If you are not tired after that, you did not work hard enough. This anaerobic has been shown in studies to burn 10X more body fat than cardio.
Feel free to throw in the occasional 5K race, but most of your training should be sprint-rest-sprint-rest. Research continues to pile showing that marathoners have just as much heart scarring and elevated heart enzymes as the average pot-bellied couch potato! They may be thinner than you but it's unlikely they are healthier than you.
And for Pete's sake, please tell your body to keep muscle mass by lifting weight a few times a week. Muscle mass keeps you lean. Hire a professional though to do it the right way. Now, go get'em, tiger!
ABOUT THE AUTHOR
Jason McCammon, B.S., NFPT-CPT, is president of I.Q.FIT Fitness & Wellness Center.