There are four ways to quick-edit your nutrition for a full day:
Option 1:
Tap the + button near the bottom of the screen
Select “Edit Day”
Enter values for calories and/or macros
Tap the checkmark to save
Option 2:
Tap on the “Data & Habits” widget from your dashboard
Make sure you’ve selected the “All” or “Nutrition” view of your habits
Tap on the calendar day you’d like to edit
Enter values for calories and/or macros
Tap the checkmark to save
Option 3:
Scroll down to the “Nutrition” widget on your dashboard. Tap it
Tap the + button at the very top right corner of the screen
Select the day you’d like to edit by tapping the date element in the top middle of the editor page
Enter values for calories and/or macros
Tap the checkmark to save
Option 4:
Scroll down to the “Nutrition” widget on your dashboard. Tap it
Scroll down to the “Data” section of the Nutrition page
Tap the pencil icon beside the day you’d like to edit
Enter values for calories and/or macros
Tap the checkmark to save