Fitness trackers

The problem with calorie counters on fitness trackers

IIf you use an activity tracker, or even just an exercise machine at home or at the gym, what is the most visible metric it displays? In most cases, this is probably an estimate of the calories you’ve burned. In fact, on most devices, you can’t turn off the calorie count even if you want to.

Yet these estimates are notoriously inaccurate: A study from the Stanford University School of Medicine compared seven different wrist-worn fitness trackers and found that the more the accurate estimate of energy expenditure (in other words, calories burned) was 27% off. The least accurate was a whopping 93% off. None of the devices provided estimates of energy expenditure “within an acceptable range of error”, the researchers concluded.

This won’t surprise anyone who knows the truth about calorie counts. Food labels telling you how many calories are in packaged foods? These are also very unreliable, as they are based on averages that disregard how our bodies digest different foods. However, they are closer than estimates of calorie expenditure: the Food and Drug Administration only allows for inaccuracies up to 20 percent.

So if these numbers are essentially meaningless, how did we come to accept them as the norm? And why do they have such power over seemingly every new fit tech released?

How Calorie Counting Invaded Our Brains

The history of calorie counting dates back to the 1800s, and it’s pretty weird. The calorie existed as a measure of energy since the 1820s, but it was not originally used to measure anything in the human body. That is, until 1896, when a researcher named Wilbur O. Atwater put a graduate student inside a calorimeter, a device designed to measure the energy generated by explosives and engines. The machine measured everything the student ate and his energy output, showing that human bodies absorb and release energy like machines or bombs (yikes).

However, calorie counting for weight loss only became popular a few decades later. It happened in 1918, when physician and columnist Lulu Hunt Peters published a book called Food and health: with the calorie key.

Needless to say, our understanding of the human body has come a long way since 1918. We know, for example, that the nutritional value of foods goes far beyond simply estimating the number of calories you strength absorb it. And the many health benefits of exercise aren’t reflected in a single number.

“People have to understand that these calorie counters are built on algorithms and your body is not an algorithm. Your body needs specific things that other bodies don’t have,” says Kerry O’Grady, National Wellness Liaison with the National Eating Disorders Association. Different bodies absorb and burn calories differently (and, obviously, need more than just calories). “The more we accept these numbers, the more we’re going to stop listening to our own bodies.”

“Calorie counters are built on algorithms, and your body is not an algorithm.” —Kerry O’Grady

For her, it’s personal. “I’ve been through that,” she says. “I almost died of anorexia in my early twenties. I can’t use a tracker because it’s very triggering for me.

It’s not unusual. Experts generally suggest that anyone with a history of eating disorders, orthorexia, or obsessive habits around exercise and nutrition avoid fitness trackers. Even those without such a history might find trackers make healthy habits less fulfilling. “Quantifying everything takes a lot of the joy out of movement and food,” says personal trainer Lauren Pak. “It makes exercise and diet feel clinical, like a job.”

Some of us may look at calorie counts and ignore them, but many people are affected more than they realize. “I think the hardest part of breaking away from calorie counting is that many of us who have some experience with it might be able to stop tracking, but calorie data lives for free in our brain,” says Jessi Haggerty, RDN, Certified Intuitive Eating Counselor and Personal Trainer. For example, if you feel like you’re not allowed to “indulge” in certain foods on non-exercise days, you may not have done the exact math, but you Always think about nutrition and exercise in a way that is shaped by calorie counting.

And that idea you have of how many calories you need per day? It’s probably wrong, says Rena Eleazar, DPT, physiotherapist, sports performance coach and competitive weightlifter. “Almost in every field, the athletes I work with have this illusion of how many calories they’re expending, and they’re usually eating undernourished,” she says.

A double-edged sword

Wearables and connected devices can help some people stay on track with a workout routine and remind them of their goals. And some of the data collected by trackers can be useful. For example, heart rate information can help highlight exercise intensity and monitor the safety of some people with chronic conditions. Other metrics, like heart rate variability, can give you useful insights into how well you deal with stress, both physical and mental.

But the ubiquity of calorie counts on fitness trackers makes diet culture hard to escape. “What’s useful and what’s not depends a lot on the person,” Pak says. “You should be able to choose what you want to track. It should not be assumed that people have a weight loss goal tied to physical activity. With some systems, you can essentially get away with calorie counting by not entering your weight; others will always display an (even more fake) calorie count automatically replacing an “average” weight.

Counting calories just isn’t a good way to know what your body needs and can lead you to restrict what you eat in a way that quickly becomes unhealthy, Haggerty says. The only situation where calorie tracking might be useful, she says, is for people who struggle to eat enough to keep up with their workout, a common problem among endurance athletes. “Even so, there are ways to do it that don’t require tracking,” she says. If you’re having trouble figuring out what or how much you need to eat, Haggerty suggests working out with an anti-diet or Health at all sizes– aligned dietitian. Good rules of thumb for people who train hard, she says, are to aim for three meals and three snacks each day, and to eat within an hour of exercising.

So why do digital devices still include calories?

Most of the digital fitness companies contacted for this story would not comment on the filing, although some confirmed they saw consumer demand for calorie burn estimates. “They’re ubiquitous because people want them,” says O’Grady. “If the market didn’t demand them, they wouldn’t be here. Even though so many people know these numbers are inaccurate, they would be upset if they were removed. That’s what these tech companies are betting on. They want you to have a relationship with this number.

The diet culture is so deeply ingrained in so many of us that we cannot mentally separate calories and exercise, even when we know better.

So does that mean you have to break up with your fitness tracker? If you find yourself paying more attention to the numbers on the screen than the actual feel of your body, maybe. “You can pretty much gauge the state of your nutrition based on how you feel in the gym,” says Eleázar. If you’re exhausted with every workout, it’s a sign that something needs to change and it’s very likely that you need to eat more. Trust this sense of your own body rather than any tracker.

And even if you’re determined to keep up with your workouts, don’t underestimate the benefits of going analog. You can still use an old-fashioned pedometer to count your steps or grab a stopwatch to time your intervals, for example. “I think just writing down the details of your workout is great,” says Pak. “Then you can track your progress from week to week. Maybe this week you’ve done three sets of 10 squats with 25 pounds, and next week you’ll be doing three sets of 10 with 30 pounds. C is great progress.

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