Fitness Trackers Don’t Reveal Accurate Calorie Count, Stanford Researchers Revealed


Weight loss largely depends on calorie counting, but the latest study revealed that fitness trackers could sabotage all your efforts.

Fitness trackers have been enjoying an overwhelming popularity these days. Since its launch, Fitbit, the industry’s leading brand, has sold around 30 million of these devices. On their official website, the company claims that their devices can track calories burned, steps, distance, active minutes, floors climbed, and hourly activity. The same promises are expected from other brands like Apple Watch, Pulse On, Samsung Gear S2, Microsoft Band, and Basis Peak.

However, a team of researchers in Stanford, recently called foul after doing some tests with these trackers. They revealed in a published paper in the Journal of Personal Medicine that even though these devices claim to help users in tracking their calories and daily energy expenditure, the figures are usually inaccurate.

PulseOn, which was the least accurate, was off by a 93% percent average. Fitbit Surge, the most accurate device, was off by 27% average, according to The Guardian.

In an NPR statement, PulseOn stated that very high level of inaccuracy could suggest that the authors did not properly set all the device’s user parameters.

Of course, the consequences of these larger margins of error could be significant.

In a news release, co-author of the study and professor of cardiovascular medicine at Standford, Euan Ashley stated that people are now basing their decisions in life on the data they get from these devices.

For example, a user checks his device at the end of the day and learned to his delight that he managed to burn 1,000 calories when the truth is they burned a mere 730. He might have a glass of wine or extra dessert since he already assumed that he was able to meet his goal.


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Over time, these excesses will add up. In this case, it will be an additional 1,890 calories every week that the user is not even aware of. Every pound of fat is made up of 3,500 calories.

Tim Church, a professor of preventative medicine at Louisiana State University’s Pennington Biomedical Research Center who was not part of the study, said that it is merely human nature. People check the inaccurate counts, and they assume that they earned some ice cream or a muffin, and during the process, they sabotage their weight loss program. It’s true that there are errors when utilizing a device like this is unavoidable, yet some scientists said this must be far lower.

According to Anna Shcherbina, the co-author of the study and a graduate student in Stanford, for lay users, in non-medical settings, they like to keep the error under ten percent. One of the key problems was the difference in the body compositions of the users. She also added that it is difficult to train an algorithm that’d be accurate in a variety of people due to the reason that energy expenditure is based on the fitness level, weight, and height of a person.

The participants of the study included a diversity of ages, men and women, and researchers looked at the diversity of the skin tone and weight and size to represent and try the population. The devices proved most precise for white women who were fit, which only means that for people who really want to lose weight, the error was greater.

Shcherbina also pointed out that while energy expenditure numbers were off, it is simpler to evaluate one’s heart rate that can be measured directly and not through the proxy calculations. Ashley also said that the heart rate measurement performed was better than what they expected. Majority of them were by only about five percent.

There have been some hints that such devices are not useful when it comes to weight loss. There is a multiyear study that was published in JAMA split into 2 groups almost five hundred people hoping to drop extra pounds. One group used fitness trackers, while some did not. The group with trackers lost about fifty percent less weight in comparison to those who don’t have.

The lead author of the study though that it has something to do with people interpreting fitness trackers incorrectly. Such technologies are focused on physical activity including getting your heart rate and taking steps. However, the Stanford study, suggests that the participants were working with faulty data.

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