Why you can’t trust your calorie burn fitness tracker

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For a while, before Fitbits came along, no one knew how many calories they burned each day. Of course, you can make a rough estimate based on your size, gender, and age; you can choose whether to trust calorie readings on gym treadmills and bikes.But a gadget can tell you what to think you personally keep burning this whole, special day is revolutionary. This is also wrong. It’s still wrong.

How Fitness Trackers Calculate Calorie Burn

Before we consider the accuracy of fitness trackers, let’s see what they actually do. Most trackers use an accelerometer to determine when and how much your body moves. If you have a watch on your wrist that rhythmically swings back and forth while bouncing up and down, your gadget will guess that you must be walking. If there’s a quicker bounce and your wrists move less, you’re probably running.

This is the basic idea of ​​how trackers detect the steps you are taking. If you pay attention to your step count, you already know some of the ways this can be inaccurate. For example, if you’re shopping, putting your hand on the cart handle may result in no credit for the steps you take. (A wearable that clips to the torso would be more accurate, but manufacturers seem to be moving away from clip-on.)

Then there’s the heart rate sensor. Since your hands don’t always move predictably during exercise, it’s easier to just tell your watch that you’re going to be cycling or doing yoga or something. The gadget then uses your heart rate to make an educated guess about how much work your body is doing.

Regardless of the source of the data—heart rate, exercise, or a combination—the gadget uses a formula to calculate how many calories it thinks you’re burning. Your age, weight and gender may affect this equation.So fitness trackers don’t actually Know How many calories you’ve burned; instead, it’s a number based on incomplete information.

Factors That Can Affect Fitness Tracker Accuracy

If we were robots, all constructed the same and all moving in predictable patterns, this approach might work. But humans are complex, and technology is often confused.

For example, you may get a different number of steps If you put a gadget on your right and left wrist. Optical heart rate sensor used by many trackers Not very accurate on dark skin.

Those questions relate to the data the trackers collect, but there’s also how the algorithms put them together to get the numbers they show you when they say how many calories you’ve burned. Companies making fitness trackers don’t need to publish their algorithms or verify that their calorie counts are accurate. They just put the device on the market and you can compare wearables on shopping sites, there is no information about their accuracy other than the company’s statement.

Researchers are interested in the accuracy of fitness trackers, which seems like a good thing. They hope to be able to use wearables in research, or recommend them to individuals and healthcare providers.

But there are huge delays in actually getting this information, and it’s often posted too late to be useful. By the time a researcher buys a batch of the latest model, conducts research, writes an article, submits it to a journal, and finally publishes it, several years may have passed and the company has moved on to the next model.

With that caveat, I still think it’s useful to look at some research on fitness trackers to see what themes come up.Yes any Which of them are good at estimating your calorie consumption?

What the study says about the accuracy of fitness trackers

Well, it’s time for the bad news.One Learning from 2020A variety of gadgets, including Apple, Garmin, Polar, and Fitbit products, were studied and found to be more inaccurate than accurate across all devices. The authors considered the device to be accurate if it read plus or minus 3 percent compared to a more accurate measure of energy expenditure (i.e., calorie burn) in a lab setting. Here’s how some top brands fared:

  • Garmins underestimated calorie burn 69% of the time.
  • The Apple Watch overestimated calorie consumption by 58%.
  • Polar devices overestimated calorie burn 69% of the time.
  • Fitbits underestimates 48% of the time and overestimates 39% of the time.

Fitbits gets roughly the truth generally doesn’t mean they are useful. If your device is sometimes overvalued and sometimes undervalued, it’s not very helpful unless you know which is which.

One 2018 Special Review Fitbits Accuracy was found to vary widely depending on factors like wearing position (torso is more accurate than wrist), whether you’re uphill, and whether you’re walking at a constant speed or stop and start. Accuracy also varies by device, with Fitbit Classic underestimating calorie burn, and Fitbit Charge generally overestimating.These devices aren’t accurate enough to know how many calories you’re really burning

One A recent studyReleased earlier this year, comparing the Apple Watch 6, Fitbit Sense, and Polar Vantage V. The researchers had volunteers wear the three devices while sitting quietly, walking, running, cycling and doing strength training. For each activity, each gadget was rated as “Poor Accuracy,” with coefficients of variation ranging from 15% to 30%.

How do I know how many calories I’ve burned if none of these devices are accurate?

This is probably most useful if you treat calorie consumption as a number that cannot be directly measured.Think of it as a black box: I burn some unknowable numbers Calories, now what?

The only common reason you need an accurate estimate of calorie consumption is if you want to figure out how much food you need to eat.If you want to lose weight, you want eat less than you burn; if you want to gain weight, you want the opposite; if you want to make sure you keep the weight, you want to eat roughly the same amount of stuff you burn.

The cool thing is you can adjust how much you eat directly Your weight, instead of using calorie burn estimates as a middleman. Let’s say you’re training for a marathon and want to make sure you’re fueling properly. Well, if you eat less, you will start losing weight. When you start to see the scale trend down, that’s a sign that you’re adding a few hundred calories to your diet. If your weight remains stable after the adjustment, then you know you’re eating the right amount. You can always make more adjustments as you increase your training (or if you take a break to rest your sprained ankle).

We have here is a post Details on how to make these adjustments with a paid app, a set of free apps, or a DIY spreadsheet. If you’ve been using a fitness tracker and it worked for you, feel free to keep using it. However, if the tracker is no longer giving you the results you want, go ahead and leave it out of the equation.

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