MyFitnessPal is probably the largest and easiest to use food & fitness tracker currently on the market. It provides excellent tools for tracking food, macros, weight and more. The app can be installed on all mobile devices and also offers a web log in where you can print your tracking and statistics for your mentor or coach to evaluate and provide feedback. The app is FREE, or you may choose to upgrade with a paid subscription to add additional tools. Best to start with the free version, learn how to use it, then see if you need to upgrade before spending additional funds.