For some, the biggest challenge of reaching a healthy weight isn't adjusting their diet or getting more exercise -- it's resisting pangs of hunger when they've already eaten enough. They might have a better time resisting that urge after today, as the US Food and Drug Administration has approved a first-of-its-kind appetite controlling device, EnteroMedics' Maestro Rechargeable System. Think of it as a pacemaker for your stomach. The device sits just under your abdomen and sends electrical pulses that both block hunger signals and send fullness signals more often. In theory, you'll lose weight simply because you have a better sense of when to stop.Don't be too quick to ask your doctor about getting one, though. For one thing, the jury's still out on how well it works. People with a test Maestro only lost 8.5 percent more excess weight in a year than people who had dummy units, and the FDA wants EnteroMedics to conduct a five-year study to see if its claims match reality in the long run. Also, your health insurance probably won't cover this -- you'll likely have to pay for the device and surgery. If Maestro does work as promised, though, it could be a lifesaver for anyone whose weight issues are normally out of their control.