If you own a smartwatch, you know the satisfaction that comes after finishing a strenuous workout, glancing at your wrist, and seeing just how many calories you’ve burned. If your aim is to be in a calorie deficit and lose weight, that figure on the watch holds a lot of importance. However, a new study suggests that your smartwatch might not be giving you accurate readings, especially if you have a higher body fat percentage.

Smartwatches have become increasingly common, not just because of their health and fitness tracking prowess, but also because of their convenience. I use mine during every workout, and while previous reports about inaccuracies have made me err on the side of caution when interpreting the numbers my watch throws out, I still find myself looking at them after every workout regardless. Considering The Conversation’s new report on smartwatch inaccuracies, I might have to change that habit.