Here's a cool new device that tracks calories spent, steps taken, and how soundly you sleep all for about $100. It's called the FitBit.
The downside to devices that calculate your caloric expenditure, like the treadmill or bike at the gym, is that the results tend to overstate the actual amount of calories your burned. The formulas use your body weight to estimate your basal metabolic rate and then return a total calories burned figure. But, you have to subtract the amount of calories that you burn just to be alive (also referred to as Basal Metabolic Rate). The difference is usually around 20%. The Fitbit group claims that their device is very accurate. I haven't seen the proof yet though.
One of the interesting features of the device is the monitoring of sleep. It does this by detecting motion of your arm. The assumption is that deep sleep renders you motionless and when you sleep fitfully you move around- roll, turn, get up, etc., and the device detects this using the same type of sensor in the Wii system.
I'm curious how well this thing works and being the early adopter type, may give it a go. If I do, I'll let you know what I think.
