Harvard Health Blog
Activity tracker may not be the key to weight loss
A delightful and dangerous season approaches. While fall brings bright colors and refreshingly cooler weather, it also brings Halloween candy, Thanksgiving pies, and other holiday treats. Around this time of year, weight loss is always on my mind.
In wanting to lose weight, I am definitely not alone. Traditionally, about half of the U.S. population is trying to lose weight at any given time. And it seems intuitive that it would be easier to do battle with a tempting candy bar when armed with a sleek, attractive activity tracker on my wrist.
Do activity trackers help you lose weight...
Just in time to curtail my spending, a recent study looking at the effects of wearable technology on long-term weight loss has arrived. In this work, published in JAMA in September, the authors sought to learn whether activity trackers helped people to lose more weight than a more traditional diet and exercise program.
Researchers at the University of Pittsburgh randomized 471 people aged 18 to 35 into two groups. The participants in each group were mostly women who ranged from overweight to obese, but none were morbidly obese (doctors consider morbid obesity to be a BMI > 40). To ensure a level playing field, both groups were prescribed a low-calorie diet, more exercise, and group counseling sessions for the first six months of participation. At the six-month mark, one group started to monitor their diet and activity the old-fashioned way — by adding up the number of calories they ate and the minutes of exercise completed, and recording the information in a web-based "journal." The other group was given an activity tracker to wear on the upper arm. The tracker collected exercise information and uploaded it to a website, where study participants could enter information on what they were eating. Remember, both groups received the same diet and exercise education and the same support from the research team. The only essential difference between the groups was whose responsibility it was to tabulate and record exercise.
Investigators followed the participants for two years. Both groups lost weight, and those wearing the trackers were on average eight pounds lighter at the two-year mark. But those who did not wear the trackers lost more — on average, 13 pounds.
...and keep it off?
Many of us want to lose more than eight or 13 pounds, but in the medical world, keeping off 13 pounds versus eight pounds is a big deal. This study, like many others, showed that people can lose weight in the short term. About six months after the study began, both groups had lost roughly the same amount of weight. But over the next 18 months, the group wearing the activity trackers gained more of it back than the group that did not wear trackers. This is the real heart of the issue with weight loss — keeping it off. The group that did not use the activity tracker seemed better able to do that in this study.
After reading this study, I wondered why the group that used the activity trackers did not lose more weight. It could be that the trackers provided a false sense of security regarding exercise. Perhaps they don't record calories burned accurately. Maybe participants did not use them to their full potential. This study was able to tell us that there was a difference between how these two groups lost weight — further studies will be needed to figure out why the activity trackers helped less than expected.
This study has two powerful messages for us. First, both groups were taught how much to eat and how much to exercise, and both were lighter in two years. That means that if we make real, sustainable lifestyle changes regarding diet and exercise, we can all be slimmer in 2017. But it takes ongoing perseverance. Swearing off chocolate for a few weeks and then returning to our old habits later Will. Not. Work. Secondly, the authors could not make a compelling argument that activity trackers will make it any easier for us to lose weight or keep it off. Here, we are provided with scientific information that can both help us lose weight, and make us better informed consumers.
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