The M7 chip located inside the iPhone 5s lets you track steps, distance, and calories burned. You also have access to other benefits of the Fitbit app for iOS, such as:
- Food tracking
- Weight tracking
- Setting fitness goals
- Adding friends
- Friends leaderboard
- Cheering, taunting, and messaging friends
To get started, download the Fitbit app from the app store and tap Join Fitbit. You will see a screen with Fitbit products; at the bottom of this screen, tap the tile that says "No Fitbit Yet? iPhone 5s tracks the basics." Continue through the rest of the setup flow by entering your information and creating an account. Once you have completed the setup flow you can begin tracking your data.
For more information, see Using the Fitbit app for iOS.