The Fallacy of “Calories Burned”

Written by Dave Thomas

There isn’t a person in the world who hasn’t graded the effectiveness of their workout via the amount of calories it burned, whether it be from a treadmill, a watch, a heart rate monitor, or the witchcraft sorcery some new gyms are employing (ahem, “Splat Points”).

The reality is that many folks, hell, the majority of folks still use this measurement as the singular determinant of a workout’s “effectiveness.” That is a major mistake on many levels and it makes my heart sad.

I wear a fitness watch in the gym from time to time. I know many other people that do, and this blog isn’t setting out to bash that. In fact, there’s absolutely nothing wrong with it. I’ll wear it when I want to get a general idea of a conditioning workout’s ability to drive adaptation for folks. I also find that when I wear the watch, it creates other healthy habits for myself. I tend to eat better, go on more walks, and live healthier. Might sound silly and a little pathetic, but it’s true.

I digress.

The point is not to trash the ideology of why you use fitness wearables.

What I do want you to be careful of is the practice of using ‘calories burned’ to dictate the overall efficacy of your fitness program, and brainwash your decision making by only attending high “calorie burning” workouts. A lot of fitness pros are snobs and make fun of people for this without taking the time to explain why it is limited. That annoys ten times more than training for calories burned so today, I will illustrate why it’s a very misleading primary indicator of effectiveness.

1. It’s Progressive Overload is Singular and Limited

Will you lose weight with a focus on calorie burning? Potentially. If you’re getting off your ass for the first time then yes, very good chance that forty five minute boot camps, treadmill workouts, or any regular exercise will create initial stages of modest weight loss. But as with any weight loss, if it’s not happening with a developmental portion: strength training and developing lean muscle, it is a weight loss program that is destined for plateau and long term failure.

Why?

Varied Progressive overload. Or specifically, a gaping lack thereof.

Light weight at a shit ton of volume in the name of calorie burning will work initially, until it doesn’t.

Progressive overload is the single most important aspect of changing one’s body when it comes to time spent in the gym. Simply explained, progressive overload principle states that you must make your workout harder than it was before if you want to drive physical adaptation in your body, and that most commonly and effectively occurs in the following areas:

  • Increased weight on a given movement (most common).
  • Achieving more volume in the same amount of time.
  • Lifting the same weight with better efficiency. 
  • Lifting the same weight with more power and greater contractions.
  • Less recovery needed at the same weight. 

Here’s where I may surprise you. If your efforts are exclusively calorie based, you can absolutely achieve all of those in the name of progressive overload. You can. In a long duration circuit you could go up a small amount of weight and achieve a few more reps, and you’d continue to make some progress. Only a fool would deny that. Hell, sometimes we write a workout because we want it to burn a lot of calories. Gasp.

But…

If it is ALL THAT YOU DO AND YOUR ENTIRE FOCUS, you’ll only be exposing yourself to a very singular, shitty, watered down access of progressive overload at only very small levels of benefit because your approach is singular and non-varied. The law of diminishing returns will hit you like a ton of bricks. Think of the it like caffeine. At first, it works. Too much, and it’s intended effect stops working and you get the jitters and crash. It’s the difference between one espresso and four. That’s diminishing returns.

An approach that has your heart rate at that level of caloric output for that long is inherently far more focused on aimless volume and pace than it is with taking the time to balance all that cardio with the requisite strength and muscle focus needed to actually change your body. Your increased efforts would not provide the same ratio of return because you have adapted to the single stimulus you’re giving it: light weight, super high volume.

You will quickly fail to keep making progress.

Sure, your “calories burned” would still be sky high because of what your heart rate is telling the machine, but it is not taking into account why and how your heart rate is elevated, and whether or not you are adapted to it and need variation. It’s just a number. I could tell you to chase tennis balls around a court for forty five minutes and you’d get the same result. High calorie output. You can only make progress on light weight performed for a ton of reps for so long before your body says, “Okay, what’s next? What else can you give me to force me to keep changing?”

If varied progressive overload is not at the foundation of your fitness plan then your approach only cares about volume. Volume is a variable. It is not the variable. Vary your training inputs. Some days long and steady, some days short and intense, some days in between. You don’t need a thousand different movements. You need a few dozen effective compound movements, performed regularly at varying loads, speeds, and formats.

The amount of calories you burn in a workout is a piece to a much larger puzzle. You also need to be building strength, developing muscle, eating well, sleeping, drinking water, recovering, and many other things that can never be effectively aggregated by a single caloric output measurement.

2. Wearables Aren’t Accurate

Do you think that in some crazy scheme to turn a profit, these manufacturers made their devices overestimate the amount of calories you burn so that you’re happy with the outcome and want to keep using them?

Nooooo wayyyy.

Stanford University studied the Apple Watch, Fitbit Surge, and five other popular brands of fitness watches and discovered that not a single one of them had below 20% rate of error when it came to measuring calories burned in its users. Not one.

Twenty percent is fucking massive, y’all. Who knows if the intent behind the error is nefarious or if it’s a technology that’s still just developing, but does it matter? It’s not correct.

That can also have a very damaging carryover effect to your food consumption. If the amount of calories you are burning is being misrepresented, it may lead you to make poor food choices because you think you burned a certain amount in your workout and in fact did not. This is a sneaky reason why a lot of calorie chasers don’t change their physiques much at all (that, and the fact that muscle isn’t being developed).

Tread carefully here in that supposed 600 calorie workout you’re doing. And that one thousand calorie workout your boot camp gym says you did? Hate to tell you this, but total bullshit. Science does not substantiate that kind of output for the human body in sixty minutes, and even if a workout allows you to maintain that kind of pace, it’s a terrible workout physiologically.

If you are a calorie addict who needs a place to rehabilitate yourself, start with this: go heavier, and slow down a gear.  Vary your load. Vary your pace. The best plan is one that respects all aspects of a fitness program without overdosing any one of them.