How does a fitness tracker calculate calories?

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It’s important to understand how fitness tracker calculates calories to determine how accurate your daily calorie consumption is.

For many people, utilizing a fitness tracker is a great way to keep track of your activity levels, calories burned, and how much you’re consuming; however, some people rely solely on the figures they see on their fitness tracker.

Therefore, accuracy is extremely important. In this article we’ll focus on how a fitness tracker works to calculate calories, the accuracy of fitness trackers, and other metrics they track, to help you determine how much you should rely on the information your fitness tracker is producing.

How does a Fitness Tracker Calculate Calories?

Fitness trackers calculate calories in different ways. For example, some will

  • Use BMR (which includes the information you enter when setting up the fitness tracker)
  • Utilize your heart rate (strap monitor or wrist)
  • Calculate calories if you move your arm excessively or swing it throughout the day

You’ll quickly learn that from one fitness tracker to the next, the calories burned will vary greatly. For this reason, you shouldn’t rely solely on your fitness tracker as a means for tracking calories, but instead, as a gauge as to how much you’re burning throughout the day.

One of the primary reasons fitness trackers aren’t an accurate representation of calories burned is that the number of calories burned varies greatly based upon the type of activity you’re engaged in.

Furthermore, some fitness trackers overcalculate while some undercalculate calories burned excessively. This can result in wearers over or under-doing it at the gym, and overeating because they believe they’re burning more calories than they are.

A majority of fitness trackers calculate your calories burned on averages. For example, the Fitbit combines your BMR (resting metabolic rate) and activity-based upon the figures you put into the tracker (weight, age, height, etc).

Some devices also track heart rate, which will increase accuracy a little, but isn’t 100% accurate either. And, fitness trackers calculate a base rate of calories while you’re sleeping based upon your weight. But, this doesn’t account for the region, movement at night, or other external factors.

Note: As you can see, inconsistencies are possible. Therefore, use your fitness tracker as a gauge/guide, rather than an accurate representation of how many calories you burn each day.

What is the best way to Track Calories Burned?

This isn’t to say toss your fitness tracker, quite the opposite, you should use your fitness tracker as a daily average. But, you’ll want to pay attention to other aspects as well.

For example, use online calorie-tracking apps to help you get a better idea of how much you’re moving.

Also, wearing a heart rate monitor is going to increase accuracy immensely. The reason for this is that it takes into account the work your body is doing, not just an average person of the same age/weight/height. MET (metabolic equivalent) charts are also beneficial. Again, these are just averages.

Think of it this way. Use these charts, trackers, and online apps to help you get a basic idea of averages. It’s nearly impossible to determine what your body is doing 100% of the time.

And, in one workout you might be a little more intense than in another, even if you’re going at the same rate/speed.

So, this will also cause differentiation in your results. Rely on these guides and devices for averages, as opposed to thinking of them as 100% precision.

Is the Fitbit Accurate for Tracking Calories?

According to a recent study, the Fitbit Surge had the best accuracy in tracking calories. The Fitbit does utilize your BMR, however, inaccuracies are possible in these calculations.

Think about it. If you put in 200 pounds, instead of 202 pounds, this will result in inconsistencies. The same with your height and age. Everything matters when it comes to tracking calories.

The Fitbit also has it’s own “averages” in place based on the type of activity you’re performing. Therefore, a 10 MPH run may indicate you’re burning 20 calories per minute as a 150-pound runner. If you look at an online MET chart, however, this same speed might state you’re burning 22 calories per minute.

Although the differences are small, the difference can be large at the end of the day. What this suggests is that your Fitbit can serve as a guide to help you achieve weight loss and fitness goals.

But, utilize the figures loosely, and don’t eat more just because you ran a little extra today. Don’t think of the calories you burned as “extra,” as this will lead to weight gain.

Instead, focus on averages, and using the fitness tracker as a guideline for planning your fitness goals.

How Does a Fitbit Track Calories You’ve Consumed?

Fitbit utilizes a Food plan to track your caloric consumption. It’s similar to MyFitnessPal and other online-tracking apps. Again, these figures are used as averages, not absolutes. To track your food you will

  • Create a food plan
  • Input your weight, goal weight, and activity (including intensity)
  • Fitbit will then determine your daily “calorie goal” based on this information
  • You’ll input the foods you eat every day and drinks you consume
  • Fitbit has some stored foods (again, these aren’t 100% accurate) for quick additions
  • You can create meals and save them if you eat the same foods daily

The best way to guarantee you’re eating the right amount is to read nutrition labels and manually input the information into the Fitbit plan. Otherwise, you’re relying on averages and information entered by other users.

If you use the same numbers every day, this won’t be a problem. But, if one day you manually input 110 calories for 4 oz of chicken breast, and some days use the 100 calories (which another user entered), this will result in inconsistencies in your diet. So, maintain the same formulas and information daily, for the best results and accuracy.

Final Thoughts… Should you Listen to your Fitbit?

Here we’ve covered how fitness tracker calculate calories. For those who rely on their fitness tracker for daily tracking, it’s going to give you a good idea of how much you’re burning, and how much you’re consuming.

However, you shouldn’t solely rely on your fitness tracker, as the results aren’t 100% accurate. Even those fitness trackers with heart rate monitors can give incorrect information and readouts.

Ultimately, you should rely on your fitness tracker as just that… a tracker! Don’t allow it to consume your life, nor should it dictate your diet and exercise regimen 100%.

It’s a good gauge as to how much you’re burning throughout the day, how many calories you’re consuming, and what your daily activity level is. If you use it every day, it can help you achieve your fitness goals.

But, the figures should be viewed as a loose representation of your caloric burn, intake, and daily expenditure.

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