The following originally appeared on The Upshot (copyright 2017, The New York Times Company).
I once received a lot of blowback for an Upshot article in which I showed (with evidence) that exercise is not the key to weight loss. Diet is. Many, many readers cannot wrap their head around the notion that adding physical activity, and therefore burning more calories, doesn’t necessarily translate into results on the scale.
Well, here we go again because some of those folks also believe that fitness devices — Fitbit, Vivosmart, Apple Watch — must be helpful in losing weight. Unfortunately, evidence doesn’t support this belief either.
For some time, people have been trying to prove devices like these succeed in promoting weight loss. In 2011, a study compared four groups getting a mixture of behavioral weight loss programs and use of an armband that measured activity and energy expenditure. All the intervention groups lost weight, but those with behavioral programs and technology lost the most. The sample size of each group (fewer than 50) and the large dropout rate of the study should temper enthusiasm, though. The sample was also mostly female, and more than three-quarters of them had college degrees, so the results may not be entirely generalizable.
In 2015, another study, the PACE-Lift trial, was also inconclusive. Researchers randomly assigned 250 people ages 60 to 75 to one of two groups. The first group received four physical activity consultations from primary care nurses over three months; a pedometer; and a physical activity diary. The other received “usual care.” All patients were given accelerometers to measure their activity, although only the control group saw the results. One year later, those in the pedometer group were taking an average of about 600 more steps per day, and had about 40 more minutes of activity a week.
But it’s hard in a trial like this to know how much of that was because of the pedometer and the feedback, and how much was because of the nurse visits and coaching.
What was needed was a large, well-designed study that truly teased out the contribution of wearable tech to weight loss programs. Last year, the results of such a study, the IDEA trial, were published.
The trial took place at the University of Pittsburgh between 2010 and 2012, and it involved more than 470 adults between the ages of 18 and 35. All of them were put on a low-calorie diet, had group counseling sessions and were advised to increase their physical activity. Six months into the intervention, all were given telephone counseling sessions, text-message prompts and study materials online.
At that time, though, half were also given wearable tech devices that monitored their activity and connected to a website to help provide feedback. All participants were followed for 18 more months.
At the end of the two years, which is pretty long for a weight loss study, those without access to the wearable technology lost an average of 13 pounds. Those with the wearable tech lost an average of 7.7 pounds.
It’s hard for many to accept, so I’m going to state the results again: Those people who used the wearable tech for 18 months lost significantly less weight than those who didn’t.
You may rightfully point out that the primary reason to wear the devices isn’t to lose weight — it’s to be more active. But even in this respect, it didn’t work nearly as well as we might hope. In the IDEA trial, those who employed the technology were no more physically active than those who didn’t. They also weren’t more fit.
Many new technologies, and dietary supplements and new diets, are sold to the public with little actual research behind them. Wearable technology to encourage fitness is no different. Somehow, in the past few years, it has become collectively understood that we need to take 10,000 steps a day. But there’s no magic behind that number. There’s no reason to believe that hitting this arbitrary goal is somehow life-changing.
Exercise is worthwhile for its own sake. Of course, many people can enjoy using wearable tech without tying it to weight loss goals. I have owned a Fitbit, a Nike FuelBand and an Apple Watch. I still wear the watch because I like many of its features. When I first bought it, I liked how it tracked my daily 30 minutes of physical activity and reminded me to stand up every so often.
But I realized over time that I didn’t really need it. After some months, getting 30 minutes of activity a day (the recommended amount) became part of my routine. I learned to be more mobile and less sedentary. I didn’t need the precision or the reminders anymore.
It’s possible that the devices helped me make physical activity part of my regular routine. It’s possible that they provided a benefit. But my experience is just an anecdote, and there’s no counterfactual to help figure out whether I’d have become more active without the devices. For that, we’d need a trial. The ones that exist (like the IDEA trial) argue that the devices don’t make people exercise more.
They don’t seem to hurt, though. Other than costing money, there’s no harm in seeing if it might improve your activity over time. But if your goal is weight loss, then you might think twice about using such a device. The evidence suggests that you may do better without one.
