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  • Writer's pictureJoshua Banning

Are You Overestimating the Calories You Burn During Exercise?

Fitness devices have come a long way.

I feel like Inspector Gadget sometimes with all I can do with my Apple Watch. I've even experimented with a Whoop Strap and Oura Ring. Both of these devices track your heart rate variability and sleep. Very useful pieces of data. I loved my devices. I was curious one day and I decided to test some of the devices against each other. What I found was very interesting.

None of them all.

Some days weren't even close. This piqued my curiosity even more. So I dug even deeper into one aspect of the trackers available.

How do these devices compare for calories burned?

It seemed crazy how many "active calories" I burned during a typical fitness class. I felt like I had a good idea of how many calories I was eating and if the active calories data was correct I should be in a pretty large calorie deficit each day!

...but I wasn't losing weight.

The ACE (American Council of Exercise) estimates the average caloric burn for high-intensity exercise is about 12-15 per minute for women and 15-18 per minute for men. For moderate to low-intensity exercise, the rate is about 10 calories per minute.

This means most fitness classes will probably only burn 300-500 calories. Most classes are around 60 minutes which typically involves 10-15 to explain the movements and some light warm-up and cool down. Then less than 20 minutes of actual high-intensity exercise.

This low-calorie burn is crazy because my watch often states that the same hour burns over 1000 calories.

So why would we see such a difference?


Through the many articles I reviewed on this topic and why companies overestimate calories, the consistent answer was that they know it's wrong but it's "close enough". When you think you're burning more calories, you'll move more and it's the device that helps you with the motivation.

However, there's another impact that happens as a result. The 300-calorie cupcake isn't so bad when you supposedly burned 1400 calories in your 75-minute gym session. But, when we look at the actual caloric burn the one cupcake essentially negated the entire workout.

We justify our decisions based on the data we are provided.

So what about the "afterburn" effect?

I thought maybe the watch was factoring in the caloric burn that occurs after we complete our exercise for the day. Well, that didn't pan out either. The "afterburn" effect only accounts for about 20cals per hour. At most, we could include 150-200 more calories. So it still didn't add up.

In the end, fitness devices have a place in our health journey. They are great for motivation, but we should probably ignore the calorie data. It's impossible for these devices to be accurate without the proper equipment. ACE has conducted these tests and Apple just has tried to mimic the data through algorithms. Obviously, the data isn't at a place where we can trust it.

So should we factor in calorie burn from workouts into our daily calories?

Yeah, sure. However, put the workouts into a proper calculator, and then regardless of your workout, make that caloric estimate your target.

We have a great calculator on our website to help find out how many calories you could target.

What about sleep data?

As for sleep and some of the other metrics the watches, straps, rings etc. provide. Well, Matt Walsh, one of the chief scientists for the Oura ring and expert sleep researcher, stated that at best these devices are around 60% accurate on this data as well.

What device would you recommend?

So, personally, I can't wait for researchers to understand the data but for now, we'll have to use the best tool we have... our body. Listening to our body and tuning into how food and exercise make us feel is still the best tool we have to understand caloric burn.

Stay tuned for more helpful tips and delicious recipes to help you on your journey.



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