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My fitness trackers took me hostage

I logged steps and macronutrients and REM sleep. It took running on empty to realize the perils of pursuing the quantified self.

María Hergueta for The Boston Globe

The one time I cried in public I was 20 years old. I was in a matching black Nike Pro spandex bra and shorts set with 12 pairs of strange eyes fixated on my body, which was floating in a glass tank, and somehow I was hot and clammy despite being underwater. It was data collection day in my undergraduate Exercise Physiology Lab at the University of Miami, and we were contrasting the accuracy of various body composition assessment tools to complement our studies on the effectiveness of lifestyle interventions.

It was my turn to play test subject for hydrostatic weighing, which was once the gold standard measure of body fat percentage. It involves completely submerging yourself in a tank filled with tap-cold water. Because fat mass is less dense than water, a person with more body fat weighs less in the water, and you can use this principle to determine how much of a person is fat-free mass, and how much of them is fat. But air is also less dense than water, so to avoid confounding your data you have to release all of the volume from your lungs while totally subaquatic and maintain this state of emptiness for as long as it takes for the lab tech to collect what they need, which is quite a long time if they’re an undergraduate trainee. During this time you have nothing to do but become acutely aware that you’re practically naked in front of your peers, including your class crush. They all watch you squirm in your tiny sportswear from the drier, freer side of the glass until you accidentally inhale a mouthful of water and the professor has to pull you out and administer a pseudo-Heimlich maneuver to clear your pipes.


At least that’s how it went for me before I excused myself to cry in the bathroom. When I came back, the professor told me that obviously I wasn’t very good in the water so my data would have to be scrapped, but I felt kind of relieved because that meant I didn’t have to know the true amount of excess fat I had on my body compared with the rest of the class, which was full of Division One athletes and coked-out models.

My relief withered when the professor brought out the skin calipers. My classmates and I poked and prodded each other’s stomachs and thighs to conclude what turned out to be one of the most ego-shattering experiences of my young adult life. We ran these numbers against our VO2 Max, a measure of aerobic capacity, as well as against our mile-run time and sit-to-stand performance. We did all of this testing in front of each other and had to disclose our measurements to our classmates for analysis and reporting. I was more fit than the models — I was a regular gym rat and a weekend jogger — but I also had more subcutaneous body fat. The athletes had less fat than I did and were more fit. I couldn’t claim superiority in any category.


What I didn’t know at the time is that the exceedingly detailed and public qualities that made measuring my body so unnerving are the same qualities that would make such measurements attractive and, in the end, addictive. For those outside of the lab, fitness trackers enable this same arc. Strapped on the wrists of 30 percent of US adults, wearable health devices such as Fitbits and Apple Watches promise to turn metrics that might normally lead to self-flagellation into ones that are self-serving.


But a lot of us end up on a spiteful path. Once the lore of “the quantified self” cracks its way into your psyche, you begin to feel almost spiritually intrigued by this idea of being so in tune with yourself. Then you get really into fitness tracking for a while, becoming aware of every activity and all consumption, until one day you wake up and you’re somehow dreading knowing too much about your body again, and you wonder if this promised health-promoting journey is really benefiting you enough to justify the coup d’état of headspace.

I kept my printed report from my college class locked away in a drawer in my nightstand the way we keep all things we don’t want to think about but aren’t sure we won’t want to think about sometime. Then in the next year I trained for a half marathon and gained a little confidence, and when I pulled my report back out again, it wasn’t so provocative anymore. Something about quantifying the state of my body appealed to my competitive nature. It seemed like a useful goal-setting tool to have solid figures as benchmarks to beat, and I’d been indoctrinated enough by my studies to have a cult-like confidence in the benefits of participating in a healthy lifestyle. I knew improving these numbers would be good for me. Even though I was already fit, relatively speaking, I was aware that fitness and metabolic health track together positively. I felt empowered by understanding my physiology and had a David Goggins, Navy SEAL-inspired conviction that if I could learn self-discipline now, my life would be better for it.


So I bought an Apple Watch. On the first day I wore it, I had three two-hour-long classes, and it reminded me to stand up halfway through each of them, which I did in earnest. After a week, I was able to see exactly which days needed restructuring in order to close the rings on the interface, which intuitively depicted that I’d achieved my daily Move, Exercise, and Stand goals. It also allowed me to follow friends, and, more importantly, compete with them, sending them notifications about my performance throughout the day.

I was hooked. I subsequently downloaded all of the health and fitness tracking apps I’d heard about from “fitfluencers” on Instagram. At the height of my game, I was clocking 20,000 steps per day, logging macronutrients to the tenth of a gram in MyFitnessPal, and maintaining my status as the Local Legend for the neighborhood 5K loop on Strava. I logged every workout and did a maximal aerobic test once per month. On any given day, I knew exactly how high my pulse had gotten, how many hours of REM I’d slept, how much zinc and magnesium I’d consumed, and how many days my biomarkers had been trending in the right direction.


I felt pretty God-like, at least for a while. Watching my VO2 Max incrementally increase and my resting heart rate consistently decrease gave me a high I’d never before achieved naturally. After getting a little too comfortable with the mundane, reminding yourself of your will and corroborating it with hard numbers is revitalizing.

But as my personal autonomy inflated, so too did my impulse to evaluate others’. I remember watching my non-data-driven peers waste their days binging the latest HBO show or drunk-eating pizza rolls and finding myself genuinely, sincerely, pitying them. I felt like I’d figured out some omniscient hack, and I couldn’t understand why others weren’t catching on. Of course, I made futile attempts to share the joys of my new lifestyle by encouraging my social media following to join me in 30-day fitness challenges or a remote yoga class, but really this was all just a ruse to share that my body-recovery score was near perfect for seven days straight despite the fact that I’d certainly run more miles than you before 8 a.m. every day that week, and would you look at how perfectly I paced each mile and how beautiful my oceanside route was — it’s no wonder 64 people gave me Kudos!

I was generally convinced by this way of living until a few things started to happen. First, my stats stopped telling me the story I wanted to hear. The benefits of exercise and behavior change of any kind really are more potent for beginners. The fitter you get, the harder it is to keep getting fitter. It took hitting a wall in my progress for me to realize that I’d begun to conceptualize my metrics as a proxy for competence and aptitude. I felt like they quantified my ability to adhere to high standards and do hard things, and this valuation of physiological prestige led me to make direct correlations between my step count and my self-worth. How was I to feel generally skilled and high-achieving without a high heart rate variability to prove it?

Whatever temporary God complex I’d developed was quickly fading into anxiety and exhaustion. As much as I wished it weren’t the case, frenetically pacing around the living room at the end of the day trying to meet burgeoning step count goals and forgoing social events to fit in extra workouts is not sustainable. Lying to your friends about having to work late so you can avoid going out to eat, because restaurant dining means accepting a level of opacity in your food tracking that you know will lead to a panicked midnight 10-miler, is not a way to maintain relationships or find contentment. It is, however, a surefire way to guarantee loneliness, sleep deprivation, lack of focus, lower back pain, and chronic agitation, all of which make your numbers trend down again.

I know this sounds extreme, and it was. But others have subtler versions of the obsession and anxiety I dealt with. You might get upset, for example, if your GPS signal gives out during your long run — “If you didn’t Strava did you even work out?” is a real phenomenon psychologists have studied. Or maybe you force yourself to chug a post-pump protein shake even though you’re a little nauseous and you hate the taste. Maybe you live-stream your heart rate during tennis matches instead of relishing the play. Or maybe you take off your wearable every Friday night, because you don’t want to think about what four shots of Casamigos does to your heart.

This is all a consequence of design. Wearable fitness technology lures in users by promising to turn their athletic prowess into beautiful data visualizations that can be shared to social media with one tap. This attracts a particular demographic who is unafraid to receive a thesis about their bodies and is actually enticed by the possibility of having that broadcast to the world.

To put this another way, fitness tracker first adopters generally are already healthy by clinical standards. The obvious irony here is that these products are marketed as health technology, without doing much by way of helping sick people get healthy. Given the robust entanglement of income and health outcomes, the high price point of these products probably makes them inaccessible to those who could benefit from them most. Based on my experience, one could even make the argument that fitness trackers often do the opposite — make healthy people sicker, more neurotic.

I wish I could say that I’d been introspective enough to recognize the subliminal consequences of fitness tracking as they were happening to me. Or I wish I had some punchy, epitomic story of how I came to my senses and quit fitness tracking for good. The reality is that a pandemic hit and life slowed down, and I moved away from a warm climate where I was wearing bikinis with questionable frequency to Boston, where a cute new boxy sweater is worth more social capital than your body fat percentage. And my obsession kind of faded away gradually as I spent more time with friends and family uninterrupted by a buzz on my wrist urging me to stand up and move around or to meet my protein goal by 10 p.m. Days went by when I forgot to charge my wearable until eventually I stopped putting it on altogether.

This is all a bit of a shame because wearables do provide valuable insights in the aggregate. The sheer amount of data they collect allows for the recognition of trends previously gone undetected. They can end once and for all, for example, the guilt associated with that third cup of coffee (caffeine improves post-workout recovery by 6 percent — live a little!). They can tell us just how bad alcohol is for health (really bad), how bad late meals are for health (kind of bad), and how good gratitude is for health (hearteningly good). They can even offer some welcomed whimsy when they tell us just how beneficial our pets are for well-being (sharing a bed with your dog improves recovery by 3 percent). They’re also adept at early detection of COVID-19 and sickness generally.

My point is that wearable health technology has vast future implications for health and human performance, but it shouldn’t be designed with perfect optimization in mind. Not everyone needs to train like an Olympian, nor should they. In fact, if wearables take away from peace of mind and simple joys, they’re not optimizing at all. My ideal wearable is one that I want to wear but not too badly. One that gleans useful insights from my activities without nudging me to be competitive and self-obsessed by default. One that leverages its impressive amount of data for clinical betterment rather than, or at least in addition to, self-optimization for the athletically elite. The Goldilocks of fitness trackers would help me toe the line between indifference and neuroticism.

Until that device arrives, I think I’m healthy enough.

Eloise Davenport is a researcher and entrepreneur in Boston. She is pursuing her PhD in cognitive psychology.