…no really. The whole purpose of having these fitness trackers is to provide data about your daily habits. While no one should expect these things to nail an exact number, it’s supposed to be giving you reasonably accurate data, let’s say within five percent of a value. In my attempts to calibrate the Basis against trusted and known baselines (my FitBit that I have also calibrated, a Garmin GPS watch with heart rate monitor), I have never been able to get the Basis to get the calorie estimates to be within better than 200 calories over (always over) the other estimates. In some cases it could be 400-500 calories off. This is counter-intuitive since it has heart rate data to use in the calorie calculations.

The most basic calorie estimate would take your age, height, weight and gender and come up with a number. You can refine that by estimating activity levels to differentiate how active you are versus a baseline. This is the point where fitness trackers come in handy. Because they can measure how much you are moving all day you don’t have to guess about how active you are, you can measure it. I know that I was a lot more sedentary than I was giving myself credit for, which was patently obvious when I started wearing the FitBit. However these devices only measure motion, they don’t measure how your body reacts to it. They have your body information, so it would calculate that the same number of steps by a young man weighing 300 pounds would be different from an old woman that weighs 100. However a fit person would see his cardiovascular system respond very different from a sedentary person. The heart rate monitor is supposed to provide yet another metric to refine the base estimate. So what is going on with the Basis?

The crux of the problem, from what I can tell, is that their formula doesn’t take into account age or weight at all. To test this I did something drastic. While I am a forty year old 195 pound guy I decided to tell the Basis system that I am a 70 year old 140 pound guy. I could have made the profile even more drastically different but there is no need. If there wasn’t some change in the calculations for such a drastic body measurement difference then things are fundamentally broken. What were the results?

My routine for Tuesday and Thursday were pretty much the same. I did mostly sitting office work, had about 7 hours of sleep and didn’t exercise. According to my FitBit, which I trust more at this point, I walked 7086 steps on Tuesday and 6598 on Thursday. This netted an energy expenditure of 2432 and 2422, respectively.

Now, just for a baseline, if you go to your standard calorie expenditure chart that is solely based on gender, height, weight and activity level I would burn between 2300 and 2600, depending on if you listed my activities as “sedentary” or “light active.” What did the Basis determine for all this? For Tuesday Basis says I walked 6626 steps and burned 2830 calories. For Thursday it determined that I walked 6208 steps and burned 2815 calories. Now, according to what Basis knows I am now 30 years older and weigh 55 pounds less. What would the most basic calculate say about the appropriate calorie range? According to that I would burn between 1600 and 1800 calories.

Something in the Basis system is fundamentally broken. Either they aren’t using weight, height and age information or they are not properly updating it in their back end. This compounded with the fact that it is always**, literally always**, over estimating the calorie burn for the day has me profoundly disappointed in this product and its utility.