(Courtesy of Fitness U Wear, llc)
Heavy bracelets weighing in at half a pound to 2 pounds, these are worn on the wrists or ankles the entire day. Like the ShaToBu, they have a measureable effect—but not much. "When you have more weight to lug around, you're going to use more energy," says Fernstrom. That said, she worries about injury. A couple of pounds doesn't sound like much, she says, "but there's nothing worse than adding too much too fast and causing damage to your joints." She suggests that beginners start with no more than a pound.