Maybe you’ve heard: Americans are becoming less fit and more fat. There are all kinds of theories about why — bigger meal portions, omnipresent corn syrup and sugar, fewer pickup stickball games after school. But people are starting to think that in many cases, body weight might somehow be linked to diet and exercise.
Now, studies have shown that if there’s some visible, omnipresent monitor of your negative behavior — spending too much money, eating too much food, using too much power in your home — you’re far more likely to correct it.
That’s the idea behind personal activity-tracking bracelets like the Nike FuelBand ($150) and the improved Jawbone Up band ($130). They make you constantly aware of how active you are (or aren’t). They let you compare your data with friends online, establishing a friendly rivalry or at least guilt. And they therefore motivate you to make changes that add up: park farther away, take the stairs, get off one bus stop early.
By DAVID POGUE