Tim Davis is seen Oct. 9 in Beaver Falls, Pa. Davis uses several apps and three wearable devices to track his physical activity, vitals and calorie intake. When Davis tipped the scales at 318 pounds two years ago, he bought a Fitbit gadget to track his physical activity and the Lose It! app on his phone to track calories. He bought a Wi-Fi-enabled scale that published his daily weight on his Twitter feed and turned to other apps to track his pulse, blood pressure, daily moods and medications. At one point, Davis said he was using 15 different apps and gadgets, which he said helped him drop 64 pounds by that following year.