“Your treadmill is making you fat.” The first time I saw it, I did a double take. “Did I read that right?” I asked myself. A second look confirmed that I had. “That’s the stupidest thing I’ve ever heard!” I thought. “Hopefully it doesn’t last long.” That was months ago, but this nasty myth is still here. Actually it’s everywhere – in the headlines, on Dr. Oz, in the blogs of your favorite Crossfit-loving, Paleo-eating fitness gurus. As more and more people take this absurd concept and spread it like some kind of weight-loss gospel, this myth has turned into an ugly hydra, growing more heads and becoming more difficult to defeat. So hand me my sword, because it’s time I took a swing at this monster.

Actually, treadmills are just a representative of the real victim of this myth, which is long, slow, distance cardiovascular exercise (LSD cardio, for short), or cardio performed at an easy to moderate effort for an extended amount of time. Perpetrators of this myth assume that this is the type of exercise you are using the treadmill for, although treadmills can also be used for sprints, intervals, hill work, and many other types of cardio workouts besides LSD.

Let me be clear – LSD cardio is not making you fat. It’s actually scientifically impossible for exercise of any kind to cause you to gain fat because the body must burn calories (often from fat) in order to function. It’s as simple as that. Why do marathon runners hit the wall? Because they have been exercising for so long and they have burned so many calories that their body is running out of fuel. If this myth were true, marathons would be frequented by Jabba the Hut look-alikes, and the elite marathoners (who train more) would be the fattest. Instead, consider that the average elite male marathoner has a body fat percentage of 3-5%, while a male in the average American population weighs in at around 25% body fat.

So why has the “treadmill = fat” myth grown so popular? For starters, I think it’s what people want to hear. Many people hate LSD cardio, believing it to be boring or difficult or both, so they latch on to any excuse for why they should no longer have to do it. Perpetuators of this myth even make their reasons sound quasi-scientific. Supposedly LSD cardio throws your hormones out of whack, devastates your metabolism, causes your body to cannibalize muscle in an attempt to generate energy, and wastes the time you should be spending on “more important” exercises like weight-lifting. But if you listen to the science rather than the hype, you will learn that LSD cardio burns calories, reduces blood pressure, improves cardiopulmonary health, aids brain function, and strengthens bones. In fact, if everyone in America spent more time on their treadmills instead of less, I believe our country would improve in ways we cannot even imagine.

So if you are doing LSD cardio as a regular part of your exercise program (awesome!), but aren’t seeing the weight-loss results you hoped for, don’t blame your treadmill. Instead here are a few other possible culprits:

• Diet – Most people over-estimate their calories burned during exercise, yet under-estimate the number of calories they consume in a day. A 150 lb person will burn about 100 calories for every mile they jog (if you weigh more or less, you’ll burn slightly more or slightly less accordingly). So if you jog two miles, but then celebrate that accomplishment by scarfing down a large Oreo Cheesequake Blizzard with extra stuff, you can expect your net calorie intake to be a little out of balance. Even if you’re not guilty of so obvious a nutritional grievance, you can still re-evaluate your diet to see if you’re eating too much sugar, too little protein, too few fruits and veggies, or too big of portions.
• Sleep habits – Getting too little sleep has long been associated with weight gain because it increases both stress hormones and cravings for sugar, fat, and salt. Make sure you get 7-9 hours every night.
• Sitting time – Even if you get your recommended 30 min of activity every day, if you spend the other 23.5 hours of the day on your butt, your overall calorie burn will not likely be an impressive number. Find ways to be more active throughout the day (such as by using the stairs, walking the dog, or riding bikes with your kids) to help jump start your metabolism.
• Muscle mass – You know the saying, “Muscle weighs more than fat?” It’s true. So if you’ve been diligent in other areas, but the number on the scale is not going down, it may be because your body is burning fat but building muscle. Invest in a scale that measures body fat percentage or look for other signs that your body composition is improving, such as waist measurements and how your clothes fit. Remember that the number on the scale is probably the least important indicator of how fit and healthy you actually are (instead you should look to other factors such as your strength and endurance, as well as blood chemistry, resting heart rate, and body fat percentage in addition to your weight for a better picture of your overall health).

In the end, the most beneficial kind of exercise is the one you’ll actually do. So if you truly hate LSD cardio, then don’t do it. I give you permission. But do find something else to keep you active every day in its place. All exercise is beneficial, so there is no need to demonize any one kind. It’s time to stop this hydra and kill this myth. Your treadmill is not making you fat, so hop back on and keep moving, my friends!

– Alan