A fitness tracker promises to be your health coach, sleep expert, and training partner—all in one sleek wristband or ring. With popular options like Fitbit, Garmin, Whoop, Apple Watch, and Oura Ring, it’s easy to believe these devices are essential for anyone serious about their health.
Is a fitness tracker worth it?
Maybe. But not for the reasons you were thinking of.
These devices offer an enticing sense of control. With a glance at your wrist or phone, you’re told how well you slept, how many calories you burned, and whether you’re “ready” to train today. It’s data-driven and seemingly scientific—but is it really helping?
Why a fitness tracker isn’t as useful as you think
Despite their popularity, the fitness tracker has significant limitations. Many people assume these devices offer objective, medically relevant insights. In reality, much of what they measure is inconsistent, oversimplified, or outright misleading.
The issue isn’t the idea of tracking—it’s the illusion of precision. A fitness tracker gives numbers, graphs, and scores, but these don’t always reflect what’s actually happening in your body.
Sleep and recovery data falls short
Most fitness trackers claim to monitor sleep quality and recovery status using heart rate, motion sensors, and sometimes skin temperature or oxygen saturation. But wrist-worn devices are not medical-grade sleep monitors. They often misclassify sleep stages and can’t reliably distinguish between deep sleep, REM, or just lying still in bed.
Recovery scores are another area where confidence outweighs accuracy. Many trackers provide daily readiness scores based on heart rate variability (HRV), resting heart rate, and recent activity. But HRV is highly sensitive to stress, hydration, alcohol, and even time of day—yet this complexity is rarely explained to the user. As a result, people may delay workouts based on a low score, or push themselves when their body isn’t actually ready, all because a device told them to.
Even worse, these scores can become a source of stress. Feeling like you “slept badly” or are “not recovered” based on a number can influence your mood and mindset for the whole day.
Calorie tracking is wildly inaccurate
Another big promise of the fitness tracker is calorie tracking. The idea that you can “burn off” what you eat or manage weight by hitting a certain calorie burn target is tempting—but deeply flawed.
Numerous studies have shown that fitness trackers can be off by as much as 40–80% when estimating energy expenditure. They rely on general formulas that can’t account for differences in body composition, fitness level, metabolism, or how your body responds to different types of activity.
If you’re using a fitness tracker to guide your nutrition decisions—whether it’s eating more or restricting intake—you may be operating on faulty information. And that can lead to underfueling, overtraining, or frustration when progress stalls despite your best efforts.
It can create more stress than progress
A common but less talked-about side effect of using a fitness tracker is anxiety. What starts as a fun tool can quickly become a constant stream of judgment. “You didn’t sleep enough.” “You haven’t moved enough.” “You’re not recovered.” For many users, especially those prone to perfectionism, this creates unnecessary pressure.
Instead of helping people become more in tune with their bodies, a tracker can do the opposite: teach them to ignore internal cues and trust a number on a screen. It can turn recovery into a game, rest into guilt, and progress into comparison.
When a fitness tracker is genuinely useful
Now, let’s give credit where it’s due. A fitness tracker can be incredibly helpful in one specific area: tracking speed, distance, and elevation.
If you’re into running, cycling, hiking, or endurance training, GPS-enabled trackers offer useful data. They help you measure pace, elevation gain, route details, and training volume over time. These are real metrics that can guide performance and help avoid overtraining.
For those sports, a tracker can be a powerful tool—not because it tells you how you feel, but because it records what you did.
The marketing machine behind every fitness tracker
So why are fitness trackers still everywhere if they’re so flawed? Because they’re part of a massive marketing machine. These companies sponsor athletes, fund fitness events, and partner with influencers who showcase their lifestyles through sleek, data-driven routines.
Honest, critical discussion around their limitations is hard to find. Most articles and reviews are promotional or based on surface-level testing. You have to dig deep to find real critiques, and by then, most consumers are already sold.
So… should you buy a fitness tracker?
Maybe.
Not for tracking your sleep, managing recovery, or calculating calorie burn—they’re simply not accurate or reliable enough for that. But if you’re someone who enjoys endurance sports and wants to track how far, how fast, and how high you’ve gone, a fitness tracker can be a genuinely helpful tool.
Just know what you’re buying. Don’t expect it to be smarter than your body. Don’t let it replace intuition, rest, or common sense. Use it if it adds value—but feel free to leave it behind if it doesn’t.
Sometimes, the best feedback is the kind you don’t need a screen to see or a graph to validate.
You’re already equipped with the most powerful tracker there is: your own awareness. A coach overseeing your progress. And maybe pen and parer.
Reading:
- Shcherbina et al., Journal of Personalized Medicine (2017) – Accuracy of heart rate and calorie measurements in fitness trackers.
- de Zambotti et al., Medical Sciences (2016) – Wearable sleep technology and its limitations compared to clinical tools.
- Hernando et al., Sensors (2018) – Validation of Apple Watch HRV under stress conditions.
- AIM7 Blog (2023) – Wearables can be off by up to 20% in heart rate and 100% in calorie tracking.
- JMIR mHealth and uHealth (2024) – Evaluation of wearable trackers for condition detection (AFib, COVID-19), highlighting limitations in diagnostic accuracy.
- PMC Study on Consumer Sleep Technologies (2023) – Analysis of 11 commercial trackers (Apple, Fitbit, Oura, etc.) shows only moderate accuracy in sleep staging.
