We’ve all seen them…
Pictures of a smartwatch displaying the number of calories someone has burned at the gym or on a run, usually accompanied with the red-faced emoji.
However, the issue is that these watches are horrible at estimating energy expenditure.
All of them.
How accurate are smartwatches for calories burned?
On average, they’re about 30% inaccurate – so if your watch says you burned 300 calories, the true number could be anywhere from 210 – 390. And this is just an average, some are even more inaccurate than this!
If you’re someone who ‘eats back’ the calories that you’ve burned then the chances are you’re unknowingly over-consuming which, if your goal is fat loss, is going to slow down your progress.
Because, outside of research settings, energy expenditure is so hard to measure it’s just not worth it (in my opinion).
Instead, I’d suggest tracking your calorie intake & making adjustments based on how your weight responds.
I can assure you that you’ll get better results this way compared to listening to what your watch is telling you!
Are smartwatches good for tracking sleep?
They’re more accurate at measuring sleep than they are at estimating energy expenditure.
However, they do tend to overestimate sleep duration. To directly quote the authors:
“This can be attributed to the dependence of actigraphy and wearables on body movement to determine sleep-wake states. Insomniacs often lie still in bed while trying to sleep, even though they are actually awake. As a result, these periods of wakefulness can be misinterpreted as sleep.”
I don’t know about you, but I don’t need to look at a watch to know whether I’m well rested or not. The same goes for ‘readiness to train’ (I hate that term so much) – if you feel great but your watch says that you should take a rest for whatever reason, are you really going to listen to it?
So what are smartwatches good for?
Telling the time.
In all seriousness, they’re probably good for tracking trends. Whilst they’re quite inaccurate as measuring the metrics they promote, they are most likely consistent inaccurate.
For example, if your watch says that you typically burn 300kcals during a spin session but one day burn 350-400kcals then you can probably deduce that you worked extra hard during that class.
Also if you notice that on Tuesdays your energy expenditure is consistently lower than average then it’s likely that this is the case due to factors such as underfuelling, training intensity, your schedule that day etc.
If you feel like you’re more health conscious when wearing one of these watches & you feel more motivated then that’s fantastic and I would say to keep wearing one.
However, I certainly wouldn’t recommend letting it dictate your calorie intake or activity levels based on how you slept the previous night.
