Have you turned your phone off and then back on again?
Here is an option for you if that doesn't work.
1. On your device, open the App Store app.
2. Click the button at the bottom to navigate to "Purchased."
3. At the top of the purchased apps page, click the button that says "Not on this iPad/iPhone."
4. Scroll through the apps until you find the Diet and Fitness tracker and click to install.
"We either make ourselves happy or miserable. The amount of work is the same." Carlos Castaneda
Live Kind. Laugh Often. Love Always.