Fitness trackers are great to see how far you’ve run and how many calories you’ve burnt, but it seems that maybe you should treat those numbers as gospel. This is because according to researchers at Researchers at Aberystwyth University, they have conducted tests on various fitness trackers only to find that most of them are way off the mark, with some by as much as 50%.
What this means is that if you’re planning on using these trackers and the calories burnt metric for your diet, maybe you shouldn’t because some of them could be way off, thus resulting in users overestimating how many calories they’ve burnt which can then affect how much food they choose to eat.
It also seems that these overestimations vary from activity to activity. For example one of the fitness trackers they tested, the Fitbit Charge 2, had underestimated the calories burnt by about 4% during a run, which we guess is acceptable. However when walking, it overestimated it by 50% which can be dangerous if you’re following a strict caloric guide.
Speaking to BBC X-Ray, Dr Thatcher said, “If you want to know the exact number of calories that you are burning during an exercise session then it doesn’t matter which device you use, you have to interpret the data with some caution.” However if you’re using a tracker simply for motivation or to measure your progress, then we suppose it shouldn’t really pose much of an issue.