The (Surprising) Truths About Fitness Trackers

Just How Accurate is Your Fitness Device?

The use of fitness trackers has become increasingly popular!

Think about it: if you are an avid fitness tracker type of person, you never leave home without it and probably are checking it several times through your day.

Now, if you are new to the fitness tracking phenomenon, here’s what you need to know:

Fitness trackers come in a variety of forms, from wrist-worn devices and rings to smartphone apps and chest straps. While Fitbits and Apple watches are most popular, several other devices and apps exist that you can wear or, downloaded to your phone.

These devices use different forms of technologies like accelerometers, heart rate monitors and algorithms to estimate your physical activity and energy expenditure.


So exactly what type of useful info can you get from these devices?

To name a few: total step count, heart rate, duration and intensity of exercise, sleep cycles, and nutrition.

Some people are using these devices to track ALL the things, others to hit daily step goals, gauge intensity levels when exercising or when working towards a weight or fat loss goal.

Now admittedly, you all know technology isn’t always perfect nor super accurate.

I hate to totally ruin your day BUT, this rings especially true for fitness tracking devices….whomp, whomp.

As both a training and nutrition coach, fitness trackers are a hot topic of conversation and have grown to be part of the conversations when coaching folks who use and reply on these devices:

“My Fitbit told me I burned 600 calories during my workout- I need to eat more food!”

Buuuuut, just HOW accurate are these trackers?

Just how accurate are the calories burned shown and to what extent, if any, should you be relying on these devices if you have weight or fat loss goals?

Today’s blog is teaching you everything you need to know about fitness trackers so that you can understand how to best interpret the data to effectively improve your health and hit your fitness goals:

  1. 4 Reasons fitness trackers are not accurate

  2. Why fitness trackers are ruining your goals

  3. 4 Ways to track progress + hit your goals!

The Problem with Fitness Trackers

While fitness trackers can provide valuable insights into activity levels and trends, their accuracy, especially when estimating calories burned, has been proven to be inaccurate upwards of 50%!

Uh, ohhhhhhh!

Here’s 4 reasons why there’s such a major discrepancy:

#1. Algorithm Limitations: Fitness trackers rely on algorithms to estimate calories burned based on input data like heart rate, activity type and duration. However, these algorithms may not accurately account for individual differences in metabolism, body composition (body fat and muscle in the body), current fitness level, and other factors.

#2. Heart Rate Variability: Some fitness trackers use heart rate data to estimate calories burned but fluctuations in heart rate are influenced by things like stress, hydration status and environmental conditions; leading to major inaccuracies in those calorie estimates.

#3. Movement Patterns: In fitness trackers, accelerometers detect motion to estimate activity level but, they may not accurately distinguish between different types of movement (e.g., walking vs. running) or account for activities like weightlifting or cycling that don’t involve significant limb movement.

Some devices are overly sensitive to the point that any hand movements such as clapping or waving records as steps taken, even though your feet never left the ground!

Side note: my device has racked up my step count an additional 300-400 steps while blow-drying my hair; showing in the app as “swimming”. This is a perfect example of how movement patterns can be misjudged.

#4. User Error: Inaccuracies in calorie estimates also stem from user error, such as forgetting to wear the device consistently, improper device placement or failing to add accurate personal information (i.e. age, weight, height) into the app.

How Fitness Trackers Ruin Your Goals

Now that you understand the reasons why these devices will never be 100% accurate, let’s talk about the impact of using this inaccurate data when workings towards your fitness goal(s):

Example: You want to lose weight or body fat and rely on your device to show total calories burned so you know how much to be eating.

Given what you now know, this is a big-time mistake that will significantly impact your efforts and completely derail your progress and results – here’s why:

Relying solely on these caloric estimates without considering other factors leads you to:

#1. Overestimate Your Caloric Deficit: A calorie deficit simply means you are eating fewer calories than you are burning, and is necessary to achieve weight or fat loss. The size of that deficit determines the speed in which you lose that weight and weight PLUS how much muscle is lost during the process (you want to avoid/limit muscle loss, regardless of your goal!).

When your fitness tracker overestimates calories burned during exercise, you are misled to believe you’ve created the calorie deficit necessary to hit your goals. You then end up of eating more calories than needed, taking yourself outta that deficit. If you are trying to lose weight or body fat, this will absolutely cause delayed or no progress. Remember, these estimates can be off by upwards of 50% – YIKES!

#2. Compensatory Eating: You may find yourself unconsciously consuming more calories or indulging in treats after seeing a high calorie burn because you’ve “earned” those extra foods/calories.

This WILL undermine weight and fat loss efforts and stall progress. If you are exercising as a means to eat more, guess what? You are fighting a losing battle: YOU CAN NOT OUT-TRAIN A POOR DIET!

#3. Misinterpretation of Results: Inaccurate calorie estimates cause you to misinterpret your progress and make adjustments to your diet or exercise routine that aren’t aligned with your specific energy needs. Again, this can potentially hinder weight and fat loss goals.

Along with that, popular apps (i.e. MyFitnessPal) used to track calories can give inaccurate calorie goals IF you’re solely using metrics from your fitness device. Once again, you may be eating far more than your body needs to achieve weight and fat loss.

4 Ways to Track Progress + Hit Goals!

While fitness trackers can be valuable tools for monitoring activity and providing motivation, it’s important you use the data wisely by adding in more accurate and effective strategies for managing weight and fat loss.

Here’s what I recommend:

#1. Focus on Consistency: Rather than fixating on calorie burn estimates, prioritize consistency in your exercise and nutrition routine. Consistency is KING and one of the biggest makers / breakers of your results. The longer you commit to and focus on making exercise a regular part of your routine and eating real, nutritious, the more progress you make and the better results you experience!

#2. Use as a Reference: Treat calorie burn estimates from fitness trackers as rough estimates rather than precise measurements; being mindful of potential inaccuracies.

#3. Listen to Your Body: Instead of using calories burned to determine what/how much to eat, listen to your body! Pay attention to hunger and fullness cues and fuel your body with nutritious foods that support your energy needs and fitness goals.

#4. Work with a Coach: There are many things that impact and health and fitness goal – far beyond what you get from looking at your tracking device. Work with a nutrition coach (that’s why I am here) so you get a fool proof, guaranteed strategy tailored to your individual needs and goals.

Understanding the limitations of these devices and using them in conjunction with other strategies can help you make informed choices so that you can stay on track with weight and fat loss goals.

By focusing on consistency, listening to your body, and working with a certified nutrition coach, you will better navigate your fitness journey with confidence and success!

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