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That's fine, I'm lying to it by saying my exercise sessions involve a shake weight.
I wouldn't trust anything to give me accurate calorie counts, it is just way to subjective. Unless it's medical grade equipment it's just not giving you anything but a educated guess
Yeah, if you've ever seen the setup they use to actually measure your energy consumption you know some gadget on your wrist can not be accurate.
Yup, best you can hope for is consistent. That can be useful in a 'am I good, should I try more, less' way.
I mean calories themselves are what happens if you burn the food in a bomb calorimeter, which bears little resemblance to what happens biochemically in your body anyway.
Agreed, and same with scales. I dont trust the number on my bathroom scale 100%, but as long as it reads consistently so I can track patterns that is what matters, even if the number itself isn't perfectly accurate. Same goes for calorie tracking via a nutrition app. The aggregate of all this information has a nice intersection that I can treat as a generally reliable idea of how I'm doing.
I like how Fitbit did so poorly that they didn’t even know what to do with those results and just removed it
I feel like anyone who counts calories to cut weight longer than a month already knows that.
My calorie counter app copies over activities from my garmin watch, and it cuts the calories burned 10-20% by default.
A couple of people I know with daily step quotas, will tell me they have done they're daily steps today when walking to lunch and back. Yes, it's like 6 blocks but it's no workout. I think these devices are giving users a false sense of exercise.
But did they say it was a workout? Or just that they've done their daily steps
Honestly, they didn't. It just seems like it from my perspective.
Are they not just looking to move more? Or are they treating it like a workout? I work from home and steps are helpful to know if I moved around enough.
If you set your step quota to 10 steps, you can both hit your quota and have gained nothing from it. This is a problem with users setting quotas too low, not a problem of the device giving bad information.
There's no real quota to set it to anyway, what's too low or too high is very subjective.
On my Samsung watch you can set a quota of min /max. I average about 10k steps a day at work.
I meant that there isn't a real science based recommendation. I aim for at least 10k steps a day as well, but even that number is made up
I have an Omron step counter, which is pretty accurate. Later on I got a smart watch (Pixel watch 3) which always counts far more steps than the Omron, like as much as 20% more. I assume it's because it's on my wrist, which moves a lot more than my hip, where the Omron is. And if it factors steps into calculating calories burned, it absolutely is going to be wrong.
My Garmin shaking on my wrist during a drive will increase my step count.
Lol same, my watch has congratulated me many times for reaching an hourly or daily step goal while I'm driving.
My exercise bike gives me a calorie count and apparently they are a bit better because the bike can actually measure how many watts of power you are generating which is the dream scenario for any calorie counting device. However even then they are only 80-85% accurate in counting calories because apparently we humans are all differently efficient in converting calories into watts. Despite this I still use that calorie number, but not to measure how many muffins I can now eat post workout, but just to compare my different workouts to each other. Recently I have been doing 1k kcal per day. Who knows maybe I'm efficient and it's actually 800kcal. But it gives me a goal to move towards each day.
Even 80-85% sounds like too much.
Compare the legs of a slim person with the legs of a severely overweight person. It's like adding shake weights onto the legs that do the pedalling.
And overweight people have different weight distributions, some have the weight on the legs some in the belly. Depending on where the weight is, that's a massive difference.
Watts input and watts output is massively different with every machine (compare e.g. an electric engine with 90+% efficiency to a combustion engine with maybe 20-30% efficiency), and humans are no different.
because apparently we humans are all differently efficient in converting calories into watts.
We're not that different though. It doesn't vary that much between people. It's pretty universally 20-25% of energy gets converted into mechanical energy, with the other 75-80% lost as heat.
What does differ is how mechanically efficient the bike is. A commercial gym stationary bike might only be 80% efficient at converting the energy put into the pedal down into the flywheel, and that is what gets read by the power meter. A high end race bike is above 95%.
Due to the roughly 25% efficiency, the math of kilojoules to calories burned is almost exactly 1:1.
Outside of a clinical lab where you get hooked up to a machine that reads the actual CO2 from your breath as you exercise, a power meter is the most accurate you're going to get though.
My Apple Watch is within 2% of the reading on the exercise bike and is noted as the most accurate in the study. I'd wager your exercise bike reading is pretty close to your actual calorie burn.
It's interesting that fitbit did so poorly. I recently picked one up and it seems to track pretty well when I'm weightlifting. The numbers are close to what I was getting when calculating by hand prior to getting the tracker.
Yes because these smart watches all use the same algorithms you do
My power meter on my bike isn't :)
It is to some minor degree as it is impossible to know exactly burn rate. Power meters FTW!
25% inaccuracy is crazy. Might as well use one of those online tools to guess it
this post was submitted on 01 Sep 2026
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