Here is a tool that lets you track your weight and access the data on your smartphone. The Perfect Fitness Scale Pro is a digital weight scale that measures body fat percentage and tracks your progress for 30 days. It shows you whether you are on the right track towards reaching your goal. It estimates your body fat percentage by sending a harmless amount of electricity through your body. The device supports up to 4 unique users. Not particularly cheap but gives you a smarter way to track your weight.