Your Watch Is Lying to You (A Little): Energy Compensation and the Calorie Myth

Your Watch Is Lying to You (A Little): Energy Compensation and the Calorie Myth

by | Sep 2, 2026 | Blogs

You train three or four times a week. You sweat, you’re sore, you’re showing up. Your watch buzzes at the end of class and tells you that you just torched 650 calories. So you do the math, and the math says the scale should be moving. It isn’t. Not the way it should.

So you start looking for what’s broken. Your metabolism. Your hormones. Your thyroid. Something.

Arnold’s Pump Club published a piece recently called “Energy Compensation: Why Your Body Burns Less Elsewhere,” and it’s worth a read, because it explains something we see in our own gym all the time. The short version: nothing is broken. Your body is just smarter than your spreadsheet.

What the Pump Club article gets right

The core idea is simple. Your body runs a budget. It gets comfortable with how much energy it spends in a day, and when you start spending big at the gym, it quietly trims spending everywhere else. You fidget less. You take the elevator without thinking about it. You sit a little longer. You don’t feel any of this happening, and you certainly don’t see it on a tracker.

The article leans on a 2021 study in Current Biology by Vincent Careau and a large team of researchers who pulled together measurements from over 1,700 adults. These weren’t wrist-watch numbers. They used the doubly labeled water method, which is the gold standard for measuring how much energy a person actually burns over a couple of weeks. What they found is that only about 72 percent of the extra calories you burn through activity actually show up as extra calories burned that day. The other 28 percent gets absorbed somewhere else in the budget.

And here’s the part that stings a bit. People carrying more body fat compensated the most. For the folks who most wanted exercise to move the needle, closer to half of their workout calories were being offset by reductions elsewhere.

The Pump Club framed it as “72 cents of every dollar counts,” and that’s a good way to think about it. The article’s conclusion is the right one too: don’t stop training. Exercise still works, and it works for a hundred reasons beyond the calorie number. Just stop treating each workout like a bank deposit that lands directly in the account you’re trying to drain.

Where I think the piece could push harder is on the tracker itself. Because energy compensation is only half the problem. The other half is that the number your watch gave you in the first place was probably wrong.

Your wearable is overcounting before your body even gets involved

Back in 2017, a team at Stanford put seven popular wearables to the test, including the Apple Watch, Fitbit, and Samsung Gear, against lab-grade equipment. Sixty people walked, ran, and cycled while the researchers measured heart rate with an EKG and energy expenditure by analyzing the oxygen and carbon dioxide in their breath.

Heart rate came out fine. Six of the seven devices were within about 5 percent, which is good enough for real training decisions.

Calories were a different story. Not one device came within the 20 percent margin the researchers considered acceptable. The best of the bunch was off by an average of 27 percent. The worst was off by 93 percent. Read that again. Some devices were reporting nearly double the calories that were actually burned.

That was 2017 and the hardware has gotten better since, but the fundamental problem hasn’t changed. A watch can measure your heart rate and your movement. It cannot measure how much oxygen you’re consuming, which is what actually determines calorie burn. So it guesses, using an algorithm built on averages of people who are not you. Your body size, your fitness level, your muscle mass, your training history, and the type of activity all change the answer, and the watch has a rough estimate of a couple of those at best.

Martial arts is especially rough on these algorithms. A wrist-worn device is fine at estimating a steady jog. It has no idea what to do with a round of pad work, a grappling exchange where your heart rate spikes but your arms barely move, or a kata where the effort is real but the wrist motion is nothing like running. It just sees an elevated heart rate and starts adding calories.

Stack the two errors together

Now put these two things side by side.

Your watch says 650 calories. In reality, the number might be closer to 450, and that’s being generous. Then your body compensates, and only about 72 percent of that 450 shows up in your daily total. Now you’re at roughly 325 real, net calories from a workout that your watch, and probably your brain, logged as 650.

That’s the gap. That’s why the math on your phone doesn’t match what’s happening on the scale. It’s not your metabolism. It’s an inflated number getting fed into a body that’s actively working to balance its books.

And it gets worse if you eat back the number your watch gave you. A hard session can genuinely increase hunger. If you reward a 650-calorie estimate with a 600-calorie meal, you’ve just spent more than you actually earned, and the tracker told you it was fine.

So what do you actually do with this?

I’m not going to tell you to throw your watch in a drawer. Heart rate data is legitimately useful. Sleep tracking is useful. Watching your resting heart rate trend down over months of training is one of the best motivators there is. Use your wearable for what it’s good at.

Just stop using the calorie number as a budget. Treat it as a rough gauge of effort, not a receipt. If you want a mental shortcut, take whatever your watch says and cut it in half. That’s closer to what you can actually count on.

Then do what the Pump Club article recommends, because it’s the right advice: protect the movement that has nothing to do with the gym. A walk after lunch. Standing during phone calls. Taking the stairs. These small things are exactly what your body quietly trims when you start training hard, so make them non-negotiable. Your training session shouldn’t buy you a lazier afternoon.

And keep your food honest. If fat loss is the goal, the workout is not permission to eat more. It’s a tool for building strength, conditioning, confidence, and the kind of body that can do hard things. The scale gets handled in the kitchen and in the hours between classes, not in the 60 minutes you spend on the mat.

Show up. Train hard. Move all day. Eat like an adult. Ignore the calorie number on your wrist.

That’s the whole formula, and none of it requires anything to be broken.

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