The must-have fitness gadgets that could make you FATTER
They claim to count the calories you burn. But as our test shows, they’re often wildly inaccurate
once for a day to see how much of a difference they would show in calories burned — the main thing most of us are worried about when it comes to tracking activity.
After my morning workout, my walk to and from work (25 minutes each way) and spending the rest of the day typing at my desk, the results ranged from 1,591 calories burned (the Jawbone UP) to a staggering 2,196 (the Misfit Shine).
That’s a difference of 605 calories that I might, or might not, be burning — or more than 4,000 calories a week, around the same number you need to cut out to lose an entire pound of fat!
It was a huge and alarming discrepancy, I had to admit. So, why was it happening?
Jon Denoris, a fitness trainer and author of The Pop-up Gym, has tested countless fitness trackers, and explains that most of them use something called an accelerometer — essentially a motion sensor — which registers your movements and feeds them into the device.
USING this information, your personal calorie expenditure is then calculated using the average burn of other people of your weight and height, making it a lot less scientific than you might think. Some are clearly more sophisticated than others.
In order to work out which was the most accurate, I visited the lab of Dylan Thompson, professor of sport, health and exercise science at the University of Bath, to be measured by his Indirect Calorimetry (IC) machine.
This involves wearing a mask that analyses the carbon dioxide and oxygen levels in your breath — the universally recognised gold stand- ard technique for calculating calorie burn. Wearing the IC mask and each of my six bands, I carried out four different activities, with different levels of intensity and ranges of movement, for eight minutes each — walking on a treadmill; cycling on a stationary bike; sitting at a computer, typing; and packing groceries — to see how they stacked up.
All the numbers represent calories burned in the eight minutes. Here are the surprising results . . .