Wireless Body Monitors
How they work: Think of them as upgraded pedometers: They track steps, calories, and weight.
How they help: The numbers don’t lie. “People often under- or overestimate their caloric intake and expenditure,” says Steven N. Blair, a professor of exercise science at the University of South Carolina, in Columbia. In a study that Blair and his colleagues conducted, published in 2011, people who used a wireless device lost twice as much weight as people who didn’t, possibly because they saw how their choices affected their weight daily.
Check out: The BodyMedia Fit Core Armband ($99, with three months of free website access, bodymedia.com) reports calorie burn with nearly 100 percent accuracy. The Fitbit Ultra clip-on tracker ($100, fitbit.com) syncs its data with your computer wirelessly.