@Sanjib, thanks for your response. You and other readers convinced me that there is actually a growing desire for taking care of oneself better, and therefore, there is a need for wearable devices like these -- and they are willing to use it whether under shirt or on a wrist. Thanks!
...in this article. It's just an advertisement in disguise. Where are the charts comparing all of the devices in question for whatever it is they do, tested concurrently on multiple subjects? Maybe, prices as well? And the most important question: How much does their accuracy drift over time?
I ask that last one because emergency aside, single-measurement accuracy is not as important as relative measurement over time. If one is overweight, biology demands that healthy weight loss will take time. During that time one should be more concerned with trends - downward trends in resting heart rate, BP, caloric intake and increase trends in daily energy use. Steps/strides/reps/cycles, let's call it a discrete motion event - these things take energy. Do more of them and you'll burn more energy. Eat less than you are today (especially sugar) and the first law of thermodynamics will probably be your friend.
Regarding measuring energy, I'd use the hard data like strides or reps. It'll be more reliable. What's more likely - that the accelerometer in one of these devices missed an event, or that one of these impersonal energy-use algorithms has erred, or is flawed? Any of these devices that can reliably yield HR and discrete motion event data over time will be useful. Anything more and you are probably wasting money.
If the wearables have these options it becomes so easy to set goals and see how you are doing to reach towards it. I guess all fitness centres will start selling them. Yes accuracy is something that is debatable. I have seen the weighing machines in different fitness centres gives different readings. HOpe these wearables will give consistent data.
How much accuracy is needed depends on the user's goals & expectations. For my workouts, for example, I use a Garmin HRM to track calories burned & heart rate zones. The default lookup tables are not very accurate for many users, so a few times a year I go for a metabolic testing session -- the gas mask connected to a laptop that measures O2 in and CO2 out while a trainer ramps you through all your HR zones, to anaerobic threshold & beyond. That individualized data then gets loaded into the HRM. Is it perfectly accurate? No. Is it more accurate than before the testing? Absolutely. Does it help me more accurately monitor my fitness activity and help me balance fat burn vs cardio strengthening activities? Yes. So it's accurate enough to meet my needs.
But as wearables become more like medical devices rather than fitness helpers, the level of accuracy will need to improve.
In my opinion, as the werables get more and more market acceptance, there will be competition among the werable manufacturers to prove how accurate and realiable their devices are.
A few years ago , those bolood sugar monitors and BP measurement machines used by the patients at home had a similar reputation. No doctor would want to believe the results shown by these machines. But today there are millions of those BP and diabetes patients who rely daily on the results of the self tests done on these comapct machines at home to monitor their blood pressure and blood sugar levels. The results shown by these machines are fairly accurate and also repetitive.
@Junko: "...And yet, I suspect the reason why many people wear those wearables today is not for the accuracy but for the looks..."
I agree with you...there are some who would like to wear these gadgets for show-off. But there are some needy people too...for example I did not pay enough attention to my fitness in my early thirties...I am nearing forties (another 2.5 years :( )...I am overweight...I got BP and then I realized I should go to gym...I hate to catch diabetes...hence I would be cautious now and would like to have something which reminds me time to time if I don't do exercise and eat more cheese or drink cola...I won't mind wearing it under my shirt!.....LOL!