Experts agree that keeping tabs on what you eat and how hard you work out can help you shed more pounds and boost the effectiveness of your workout. Research shows that stepping on the scale at least once a week can help you lose more weight and keep it off. Tracking the number of steps you take every day gets you to move more. Even writing down what you eat can double weight loss. So it's no surprise that the latest crop of high-tech diet and fitness gadgets are designed to make tracking stats like these easier than ever. Here's a roundup of 12 top-notch devices that will help take the guesswork out of shaping up so you can achieve undeniable results.