Fitness monitoring: gimmick or game-changer for the NHS?

Many people now gather data about their own bodies on personal trackers, but the jury is still out on their accuracy and effectiveness

Fitness trackers are surging in popularity, but are they any good for you? And are they any good for the doctor who is treating you?

The devices, worn on the wrist, clipped to the belt or shoved into a pocket, measure your movements and, at the very least, promise to calculate how many calories you burned on your walk to work. Some offer considerably more, with myriad sensors measuring health indicators.