If you notice your Noom icon is missing from your iPhone’s home screen, but if you go to the App Store and it says “Open”, then the app is still installed on your device. It is possible to hide icons from your Home screen, so it’s likely just stored in your App Library and you only need to place it back on the Home screen.
To see the Noom icon on your iPhone home screen again, with your iPhone unlocked, keep swiping left on the iPhone home screen until it reveals the App Library. Next, look for the Noom icon. Once you find it, long-press the Noom icon and tap Add to Home Screen to put the icon back on your iPhone’s home screen. Close the App Library and you should now see the Noom icon back with the rest of your icons.
And that’s it! Enjoy!